Phenobarbital, hyoscyamine, atropine, and scopolamine interactions

Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Acetaminophen and codeine label, Boxed warning)

Avoid administrations of TUDORZA PRESSAIR with other anticholinergic-containing drugs. (Aclidinium label, Drug interactions)

Combining alcohol with sedating medicines (opioids, benzodiazepines, sleep medicines, muscle relaxants) can cause dangerous drowsiness, slowed breathing, and overdose. (NIAAA, Harmful Interactions: Mixing Alcohol with Medicines)

• Effects on Driving and Operating Machinery: Patients receiving • alprazolam XR should be cautioned against operating machinery or driving a motor vehicle, as well as avoiding concomitant use of alcohol and other central nervous system (CNS) depressant drugs. (Alprazolam label, Warnings and precautions)

Drug Interactions : Use with strong cytochrome P450 enzyme inducers (e.g., rifampin, phenobarbital, carbamazepine, phenytoin) is not recommended because loss of efficacy may occur ( 5.5 , 7.1 ) (Apremilast label, Warnings and precautions)

Drug Class Drugs within class that are contraindicated with REYATAZ Alpha 1-adrenoreceptor antagonist Alfuzosin Anticonvulsants Carbamazepine, phenobarbital, phenytoin Antiarrhythmics Amiodarone (with ritonavir), quinidine (with ritonavir) Antimycobacterials Rifampin Antineoplastics Apalutamide, encorafenib, irinotecan, ivosidenib Antipsychotics Lurasidone (with… (Atazanavir label, Contraindications)

• Avoid concurrent use of alcohol or other central nervous system (CNS) depressants with azelastine hydrochloride and fluticasone propionate nasal spray because further decreased alertness and impairment of CNS performance may occur. (Azelastine and fluticasone label, Warnings and precautions)

…AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL EXPOSURE; NEONATAL OPIOD WITHDRAWAL SYNDROME; and RISKS FROM CONCOMITANT USE WITH ALCOHOL, BENZODIAZEPINES OR OTHER CNS DEPRESSANTS Addiction, Abuse, and Misuse Belladonna and opium suppositories expose patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to… (Belladonna and opium label, Boxed warning)

Because of its atropine-like side effects, this drug is contraindicated in pediatric patients under three years of age, and should be used with caution in older pediatric patients. (Benztropine label, Contraindications)

Anticonvulsants: carbamazepine oxcarbazepine phenobarbital phenytoin ↓ lenacapavir ↓ bictegravir Concomitant administration with carbamazepine or phenytoin is contraindicated. (Bictegravir, emtricitabine, and tenofovir alafenamide label, Drug interactions)

Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Buprenorphine label, Boxed warning)

Bupropion hydrochloride extended-release tablets (XL) are contraindicated in patients undergoing abrupt discontinuation of alcohol, benzodiazepines, barbiturates, and antiepileptic drugs [see Warnings and Precautions (5.3) and Drug Interactions (7.3)] . (Bupropion label, Contraindications)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Butalbital, acetaminophen, caffeine, and codeine label, Boxed warning)

Concomitant use of opioids or a barbiturate with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Butalbital, aspirin, caffeine, and codeine label, Boxed warning)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Butorphanol label, Boxed warning)

…induction, which may result in loss of virologic response [see Drug Interactions ( 7.2 , 7.3 ), Clinical Pharmacology ( 12.3 )] : o Anticonvulsants: Carbamazepine, oxcarbazepine, phenobarbital, phenytoin o Antimycobacterials: Rifampin, rifapentine Prior to initiation of VOCABRIA, note that use of CABENUVA (cabotegravir extended-release injectable suspension;… (Cabotegravir label, Contraindications)

Avoid chronic co-administration of strong CYP3A4 inducers (e.g., phenytoin, carbamazepine, rifampin, rifabutin, rifapentine, phenobarbital, St. (Cabozantinib label, Drug interactions)

CNS Depressants The concomitant use of EQUETRO and other CNS depressants can increase the risk of respiratory depression, profound sedation, hypotension, and syncope. (Carbamazepine label, Drug interactions)

Avoid concurrent use of Carbinoxamine Maleate Extended-Release Oral Suspension with alcohol or other central nervous system depressants because additional impairment of central nervous system performance may occur. (Carbinoxamine label, Warnings and precautions)

Avoid concurrent use of QUZYTTIR with alcohol or other CNS depressants because additional reduction in alertness and additional impairment of CNS performance may occur. (Cetirizine label, Warnings and precautions)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Chlordiazepoxide label, Warnings)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Chlordiazepoxide and clidinium label, Warnings)

Do not use in comatose states or in the presence of large amounts of central nervous system depressants (alcohol, barbiturates, narcotics, etc.). (Chlorpromazine label, Contraindications)

Table 8: Drugs That are Affected by and Affecting Ciprofloxacin Drugs That are Affected by Ciprofloxacin Drug(s) Recommendation Comments Tizanidine Contraindicated Concomitant administration of tizanidine and ciprofloxacin is contraindicated due to the potentiation of hypotensive and sedative effects of tizanidine [see Contraindications ( 4.2 )]. (Ciprofloxacin label, Drug interactions)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Clobazam label, Warnings and precautions)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Clonazepam label, Warnings)

Avoid use with other central nervous system (CNS) depressants ( 5.3 ) (Clonidine label, Warnings and precautions)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Clorazepate label, Warnings)

When possible, avoid concomitant use, with other anticholinergic medications because the risk for anticholinergic toxicity or severe gastrointestinal adverse reactions is increased [see Warnings and Precautions ( 5.7 ), Drug Interactions ( 7.1 )]. (Clozapine label, Warnings and precautions)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Codeine label, Boxed warning)

Based on its structural similarity to TCAs, concomitant use of TONMYA with: MAO inhibitors may be life-threatening [see Contraindications (4) ] , Alcohol, barbiturates, and other CNS depressants may increase the risk of adverse reactions associated with these drugs, Tramadol may increase the seizure risk, Guanethidine or other similar acting drugs may block the… (Cyclobenzaprine label, Drug interactions)

…elbasvir/grazoprevir Lipid modifying agents: lomitapide, lovastatin, simvastatin Opioid Antagonist: naloxegol PDE-5 inhibitor: sildenafil when used for treatment of pulmonary arterial hypertension Sedatives/hypnotics: orally administered midazolam, triazolam Co-administration of PREZISTA/ritonavir is contraindicated with drugs that are highly dependent on CYP3A for clearance… (Darunavir label, Contraindications)

Alpha 1-adrenoreceptor antagonist: alfuzosin Anticonvulsants: carbamazepine, phenobarbital, phenytoin Anti-gout: colchicine, in patients with renal and/or hepatic impairment Antimycobacterial: rifampin Antipsychotics: lurasidone, pimozide Cardiac Disorders: dronedarone, ivabradine, ranolazine Ergot derivatives, e.g. dihydroergotamine, ergotamine, methylergonovine… (Darunavir and cobicistat label, Contraindications)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Diazepam label, Warnings)

Usage of MOTOFEN ® in recommended doses is not likely to cause prominent anticholinergic side effects, but MOTOFEN ® should be avoided in patients in whom anticholinergic drugs are contraindicated. (Difenoxin and atropine label, Warnings)

CONTRAINDICATIONS Diphenoxylate hydrochloride and atropine sulfate is contraindicated in: • Pediatric patients less than 6 years of age due to the risks of respiratory and central nervous system (CNS) depression (see WARNINGS ). (Diphenoxylate and atropine label, Contraindications)

These drugs include, but are not limited to, the following: the anticonvulsants carbamazepine, oxcarbazepine, phenobarbital, phenytoin the androgen receptor inhibitor enzalutamide the antimycobacterials rifampin, rifapentine the cytotoxic agent mitotane St. (Doravirine label, Contraindications)

Central nervous system (CNS) depressants: Concurrent use with alcohol or other CNS depressants is not recommended ( 5.1 ) (Doxylamine and pyridoxine label, Warnings and precautions)

Rifampin and Other CYP3A Inducers Avoid rifampin or other CYP3A inducers such as phenobarbital, carbamazepine, phenytoin, and St. (Dronedarone label, Drug interactions)

Alpha 1-adrenoreceptor antagonist: alfuzosin Anticonvulsants: carbamazepine, phenobarbital, phenytoin Antimycobacterial: rifampin Antipsychotics: lurasidone, pimozide Ergot Derivatives: dihydroergotamine, ergotamine, methylergonovine Herbal Products: St. (Elvitegravir, cobicistat, emtricitabine, and tenofovir label, Contraindications)

…COMPLERA or to the class of NNRTIs [see Warnings and Precautions (5.7) , Drug Interactions (7) , and Clinical Pharmacology (12.3) ]: Anticonvulsants: carbamazepine, oxcarbazepine, phenobarbital, phenytoin Antimycobacterials: rifampin, rifapentine Glucocorticoid (systemic): dexamethasone (more than a single-dose) Herbal Products: St John's wort ( Hypericum perforatum… (Emtricitabine, rilpivirine, and tenofovir label, Contraindications)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Estazolam label, Warnings)

The use of LUNESTA with other sedative-hypnotics at bedtime or the middle of the night is not recommended. (Eszopiclone label, Warnings and precautions)

Etravirine should not be used in combination with carbamazepine, phenobarbital, or phenytoin as co-administration may cause significant decreases in etravirine plasma concentrations and loss of therapeutic effect of Etravirine. (Etravirine label, Drug interactions)

• Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Fentanyl label, Boxed warning)

…Hypericum perforatum ) Lipid modifying agents: Lomitapide, lovastatin, simvastatin Non-nucleoside reverse transcriptase inhibitor: Delavirdine PDE5 inhibitor: Sildenafil (Revatio) (for treatment of pulmonary arterial hypertension) Sedative/hypnotics: Midazolam, triazolam Hypersensitivity to fosamprenavir calcium or amprenavir (e.g., Stevens-Johnson syndrome). (Fosamprenavir label, Contraindications)

• Respiratory Depression: May occur with NEURONTIN when used with concomitant central nervous system (CNS) depressants, including opioids, or in the setting of underlying respiratory impairment. (Gabapentin label, Warnings and precautions)

Intervention Concomitant use of anticholinergic drugs with GVOKE VialDx is not recommended. (Glucagon label, Drug interactions)

• Other Conditions Exacerbated by Anticholinergic Adverse Reactions : Use is not recommended in patients with autonomic neuropathy, hyperthyroidism, cardiac disease, hiatal hernia, etc. (Glycopyrrolate label, Warnings and precautions)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Hydrocodone label, Boxed warning)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Hydrocodone and acetaminophen label, Boxed warning)

…ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; MEDICATION ERRORS; CYTOCHROME P450 3A4 INTERACTION; CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; INTERACTION WITH ALCOHOL; NEONATAL OPIOID WITHDRAWAL SYNDROME WARNING: ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION;… (Hydrocodone and chlorpheniramine label, Boxed warning)

…ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; MEDICATION ERRORS; CYTOCHROME P450 3A4 INTERACTION; CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; INTERACTION WITH ALCOHOL; NEONATAL OPIOID WITHDRAWAL SYNDROME Addiction, Abuse, and Misuse Hydrocodone bitartrate and homatropine methylbromide exposes patients and… (Hydrocodone and homatropine label, Boxed warning)

…LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; CYTOCHROME P4503A4 INTERACTION; RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; and SERIOUS CARDIOVASCULAR AND GASTROINTESTINAL EVENTS WARNING: SERIOUS AND LIFE-THREATENING RISKS FROM USE OF HYDROCODONE BITARTRATE AND IBUPROFEN TABLETS Addiction,… (Hydrocodone and ibuprofen label, Boxed warning)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death . (Hydromorphone label, Boxed warning)

Rarely, cardiac arrests and death have been reported in association with the combined use of hydroxyzine hydrochloride intramuscularly and other CNS depressants. (Hydroxyzine label, Precautions)

Hypersensitivity to ipratropium bromide or other ATROVENT HFA components Hypersensitivity to atropine or any of its derivatives Hypersensitivity to ipratropium bromide or other ATROVENT HFA components ( 4 ) (Ipratropium label, Contraindications)

CONTRAINDICATIONS Ipratropium Bromide and Albuterol Sulfate Inhalation Solution is contraindicated in patients with a history of hypersensitivity to any of its components, or to atropine and its derivatives. (Ipratropium and albuterol label, Contraindications)

Early diarrhea may be accompanied by cholinergic symptoms which may be prevented or ameliorated by atropine. (Irinotecan label, Boxed warning)

Anticonvulsants Phenobarbital Phenytoin Not recommended 2 weeks before and during TOLSURA treatment. (Itraconazole label, Drug interactions)

Benzodiazepines, Opioid Analgesics, or other CNS Depressants : Concomitant use may result in profound sedation, respiratory depression, coma, or death. (Ketamine label, Drug interactions)

This may potentiate and prolong hypnotic and sedative effects, especially with repeated dosing or chronic administration of these agents. (Ketoconazole label, Contraindications)

Concomitant administration of SUNLENCA with oxcarbazepine or phenobarbital is not recommended. (Lenacapavir label, Drug interactions)

Avoid concurrent use of alcohol or other central nervous system depressants with XYZAL. (Levocetirizine label, Warnings and precautions)

Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Levorphanol label, Boxed warning)

KALETRA once daily in combination with carbamazepine, phenobarbital, or phenytoin is not recommended. (Lopinavir and ritonavir label, Drug interactions)

Caution patients receiving LOREEV XR against operating machinery or driving a motor vehicle as well to avoid the concomitant use of alcohol and other CNS depressant drugs during treatment ( 5.4 , 7 ) (Lorazepam label, Warnings and precautions)

CONTRAINDICATIONS Loxapine is contraindicated in comatose or severe drug-induced depressed states (alcohol, barbiturates, narcotics, etc.). Loxapine is contraindicated in individuals with known hypersensitivity to dibenzoxazepines. (Loxapine label, Contraindications)

Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Meperidine label, Boxed warning)

If concomitant use with another CNS depressant is warranted, closely monitor for signs of respiratory depression and sedation, particularly during treatment initiation and dosage increases. (Metaxalone label, Warnings and precautions)

Managing Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, is a risk factor for respiratory depression and death [see Warnings and Precautions ( 5.2 )]. (Methadone label, Boxed warning)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, malignant hyperthermia, drug fever, serotonin syndrome, and primary central nervous system pathology. (Metoclopramide label, Warnings and precautions)

WARNING: PERSONNEL AND EQUIPMENT FOR MONITORING AND RESUSCITATION AND RISKS FROM CONCOMITANT USE WITH OPIOID ANALGESICS AND OTHER SEDATIVE-HYPNOTICS Personnel and Equipment for Monitoring and Resuscitation Only personnel trained in the administration of procedural sedation, and not involved in the conduct of the diagnostic or therapeutic procedure, should administer… (Midazolam label, Boxed warning)

Avoid co-administration of mifepristone and CYP3A inducers such as rifampin, rifabutin, rifapentin, phenobarbital, phenytoin, carbamazepine, and St. (Mifepristone label, Drug interactions)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Morphine label, Boxed warning)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Nalbuphine label, Boxed warning)

Risk of Recurrent Respiratory and CNS Depression : A recurrence of respiratory depression is possible, therefore, keep the patient under continued surveillance and administer repeat doses of ZURNAI using a new auto-injector with each dose while awaiting emergency medical assistance. (Nalmefene label, Warnings and precautions)

CYP2B6 Inducers (e.g., ritonavir, lopinavir, efavirenz, carbamazepine, phenobarbital, and phenytoin) may reduce efficacy by reducing bupropion exposure, avoid concomitant use. (Naltrexone and bupropion label, Drug interactions)

…due to the delayed offset of the recently discontinued CYP3A inducer [see Drug Interactions (7.3) ] : • Anticancer drugs: apalutamide, enzalutamide • Anticonvulsant: carbamazepine, phenobarbital, primidone, phenytoin • Antimycobacterials: rifampin, rifapentine • Cystic fibrosis transmembrane conductance regulator potentiators: lumacaftor/ivacaftor • Herbal products:… (Nirmatrelvir and ritonavir label, Contraindications)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Oliceridine label, Boxed warning)

• Avoid concurrent use of alcohol or other central nervous system depressants with olopatadine hydrochloride nasal solution (nasal spray) ( 5.2 ). (Olopatadine label, Warnings and precautions)

• Avoid concurrent use of alcohol or other central nervous system (CNS) depressants with RYALTRIS because additional reductions in alertness and additional impairment of CNS performance may occur. (Olopatadine and mometasone label, Warnings and precautions)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Oxazepam label, Warnings)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Oxycodone label, Boxed warning)

…LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; CYTOCHROME P450 3A4 INTERACTION; and RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS Addiction, Abuse, and Misuse Oxycodone hydrochloride tablets exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to… (Oxycodone and acetaminophen label, Boxed warning)

Risks From Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Oxymorphone label, Boxed warning)

…MITIGATION STRATEGY (REMS); LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; and RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS Addiction, Abuse, and Misuse Pentazocine and Naloxone Tablets exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to… (Pentazocine and naloxone label, Boxed warning)

CONTRAINDICATIONS Perphenazine products are contraindicated in comatose or greatly obtunded patients and in patients receiving large doses of central nervous system depressants (barbiturates, alcohol, narcotics, analgesics, or antihistamines); in the presence of existing blood dyscrasias, bone marrow depression, or liver damage; and in patients who have shown… (Perphenazine label, Contraindications)

Phenelzine sulfate should not be used in combination with dextromethorphan or with CNS depressants such as alcohol and certain narcotics. (Phenelzine label, Contraindications)

SEZABY is contraindicated in patients with: acute porphyrias [see Warnings and Precautions (5.8)], or a history of hypersensitivity reaction to phenobarbital or other barbiturates [see Warnings and Precautions (5.7)] Acute porphyrias (4) (Phenobarbital label, Contraindications)

…spasms in the urinary tract collection system, inactivation of nerve and muscle cells after administration of drugs to relax the muscles (depolarization block after depolarizing muscle relaxants), in case of intoxication due to “irreversibly acting” cholinesterase inhibitors (drugs used to treat dementia), intoxication with phosphoric acid esters or barbiturates. (Physostigmine label, Contraindications)

In patients in whom there is cause for arrest or delay in tablet passage through the gastrointestinal tract, such as those suffering from delayed gastric emptying, esophageal compression, intestinal obstruction or stricture, or those taking anticholinergic medication. (Potassium citrate label, Contraindications)

• Respiratory Depression : May occur with LYRICA when used with concomitant CNS depressants or in the setting of underlying respiratory impairment. (Pregabalin label, Warnings and precautions)

CONTRAINDICATIONS Primidone is contraindicated in: 1) patients with porphyria and 2) patients who are hypersensitive to phenobarbital (see ACTIONS ). (Primidone label, Contraindications)

Do not use in comatose states or in the presence of large amounts of central nervous system depressants (alcohol, barbiturates, narcotics, etc.). Do not use in pediatric surgery. (Prochlorperazine label, Contraindications)

…PROMETHAZINE AND RESPIRATORY DEPRESSION IN CHILDREN; MEDICATION ERRORS; INTERACTIONS WITH DRUGS AFFECTING CYTOCHROME P450 ISOENZYMES; CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; NEONATAL OPIOID WITHDRAWAL SYNDROME Addiction, Abuse, and Misuse Promethazine HCl and Codeine Phosphate Oral Solution exposes patients and other users to the risks… (Promethazine and codeine label, Boxed warning)

WARNING: RISKS WITH IMPROPER USE OF PYRIDOSTIGMINE BROMIDE After Exposure to Soman, Use Atropine and Pralidoxime Pyridostigmine bromide is for use as a pretreatment for exposure to soman nerve agent. (Pyridostigmine label, Boxed warning)

Quinidine is also contraindicated in patients who, like those with myasthenia gravis, might be adversely affected by an anticholinergic agent. (Quinidine label, Contraindications)

If concomitant administration with carbamazepine or phenobarbital cannot be avoided, frequent monitoring of anticonvulsant drug concentrations is recommended. (Quinine label, Drug interactions)

CYP3A inducers (e.g., rifampin, phenobarbital, St. (Ranolazine label, Contraindications)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Remifentanil label, Boxed warning)

Table 2: Drugs That are Contraindicated with EDURANT and EDURANT PED Drug Class Contraindicated Drugs in Class Clinical Comment Anticonvulsants Carbamazepine Oxcarbazepine Phenobarbital Phenytoin Potential for significant decreases in rilpivirine plasma concentrations due to CYP3A enzyme induction, which may result in loss of virologic response. (Rilpivirine label, Contraindications)

WARNING: DRUG-DRUG INTERACTIONS LEADING TO POTENTIALLY SERIOUS AND/OR LIFE THREATENING REACTIONS Co-administration of NORVIR with several classes of drugs including sedative hypnotics, antiarrhythmics, or ergot alkaloid preparations may result in potentially serious and/or life-threatening adverse events due to possible effects of NORVIR on the hepatic metabolism… (Ritonavir label, Boxed warning)

Concomitant use with metoclopramide, beta-blockers, or cholinomimetic and anticholinergic drugs is not recommended ( 7.1 , 7.2 , 7.3 ) (Rivastigmine label, Drug interactions)

• Drug Interactions: Use with strong cytochrome P450 enzyme inducers (e.g., rifampicin, phenobarbital, carbamazepine, phenytoin) is not recommended. (Roflumilast label, Warnings and precautions)

• Central Nervous System Depression Xyrem (sodium oxybate) is a CNS depressant. (Sodium oxybate label, Boxed warning)

Anticonvulsants: carbamazepine phenytoin phenobarbital ↓ sofosbuvir ↓ velpatasvir ↓ voxilaprevir Coadministration is not recommended. (Sofosbuvir and velpatasvir label, Drug interactions)

Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Tapentadol label, Boxed warning)

Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. (Temazepam label, Warnings)

Avoid use with strong inducers of CYP3A (e.g., rifampin, phenytoin, carbamazepine and phenobarbital) [see Clinical Pharmacology (12.3) ] . (Ticagrelor label, Drug interactions)

Avoid administration of SPIRIVA RESPIMAT with other anticholinergic-containing drugs. (Tiotropium label, Drug interactions)

Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Tramadol label, Boxed warning)

Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. (Tramadol and acetaminophen label, Boxed warning)

…(HR) b or Serotonin Syndrome (SS) c ] Agents with blood pressure-reducing effects Use with caution d Hypotension e Non-selective H1 receptor antagonists Contraindicated a Increased anticholinergic effects Beta-adrenergic blockers (see also agents or procedures with blood pressure-reducing effects) Use with the caution d More pronounced bradycardia, postural hypotension… (Tranylcypromine label, Drug interactions)

• Effects on Driving and Operating Heavy Machinery : Patients receiving triazolam should be cautioned against driving or operating heavy machinery, as well as avoiding concomitant use with alcohol and other CNS depressant drugs. (Triazolam label, Warnings and precautions)

CONTRAINDICATIONS A known hypersensitivity to phenothiazines, comatose or greatly depressed states due to central nervous system depressants and, in cases of existing blood dyscrasias, bone marrow depression and preexisting liver damage. (Trifluoperazine label, Contraindications)

Avoid co-administration of ella and drugs or herbal products such as: • barbiturates • bosentan • carbamazepine • felbamate • griseofulvin • oxcarbazepine • phenytoin • rifampin • St. (Ulipristal label, Drug interactions)

Avoid administration of Umeclidinium ELLIPTA with other anticholinergic-containing drugs. (Umeclidinium label, Drug interactions)

Avoid administration of Umeclidinium and Vilanterol ELLIPTA with other anticholinergic-containing drugs. (Umeclidinium and vilanterol label, Drug interactions)

Carbamazepine (CYP450 Induction) Not Studied In Vivo or In Vitro , but Likely to Result in Significant Reduction Contraindicated Long Acting Barbiturates (e.g., phenobarbital, mephobarbital) (CYP450 Induction) Not Studied In Vivo or In Vitro , but Likely to Result in Significant Reduction Contraindicated Phenytoin (CYP450 Induction) Significantly Reduced Increase… (Voriconazole label, Drug interactions)

The use of zaleplon with other sedative-hypnotics at bedtime or the middle of the night is not recommended (see ). (Zaleplon label, Warnings)

The use of Zolpidem Tartrate with other sedative-hypnotics (including other zolpidem products) at bedtime or the middle of the night is not recommended. (Zolpidem label, Warnings and precautions)

Inform patients also that the central nervous system depressant effects of allopurinol tablets may be additive to those of alcohol and other CNS depressants. (Allopurinol label, Warnings and precautions)

30% increase Phenobarbital (PB) Similar to aminoglutethimide. (Aminophylline label, Drug interactions)

Amoxapine may enhance the response to alcohol and the effects of barbiturates and other CNS depressants. (Amoxapine label, Drug interactions)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system pathology. (Aripiprazole label, Warnings and precautions)

…cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine Monoamine Oxidase Inhibitors, Nonselective Beta-Adrenergic Antagonists,… (Articaine and epinephrine label, Drug interactions)

Strenuous exercise, exposure to extreme heat, dehydration, and anticholinergic medications may contribute to an elevation in core body temperature; use SAPHRIS with caution in patient who may experience these conditions. (Asenapine label, Warnings and precautions)

Patients should also be cautioned that the central nervous system depressant effects of intrathecal baclofen may be additive to those of alcohol and other CNS depressants. (Baclofen label, Warnings and precautions)

Drugs that alter gastrointestinal motility: The bioavailability of thiazide-type diuretics may be increased by anticholinergic agents (e.g., atropine, biperiden), apparently due to a decrease in gastrointestinal motility and the stomach emptying rate. (Benazepril and hydrochlorothiazide label, Drug interactions)

Inducers of CYP450 liver enzymes The simultaneous administration of bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride and drugs that induce microsomal liver enzymes, such as phenytoin or phenobarbital, may accelerate the elimination of metronidazole, resulting in reduced plasma concentrations of metronidazole. (Bismuth subcitrate, metronidazole, and tetracycline label, Drug interactions)

Alcohol, barbiturates, or narcotics - potentiation of orthostatic hypotension may occur. (Bisoprolol and hydrochlorothiazide label, Precautions)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Aminoglycosides or other agents interfering with neuromuscular transmission Anticholinergic drugs Botulinum neurotoxin products Muscle relaxants Aminoglycoside antibiotics, anticholinergic agents, or any other agents that interfere with neuromuscular transmission may potentiate the effect of DAXXIFY; co-administer only with caution and close observation. (Botulinum toxin type A label, Drug interactions)

Strenuous exercise, exposure to extreme heat, dehydration, and anticholinergic medications may contribute to an elevation in core body temperature; use REXULTI with caution in patients who may experience these conditions. (Brexpiprazole label, Warnings and precautions)

Use with CNS depressants may result in an additive or potentiating effect. (Brimonidine label, Drug interactions)

Use with CNS depressants may result in an additive or potentiating effect. (Brimonidine and timolol label, Drug interactions)

Central Nervous System (CNS) depressants Antihistamines have additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, antianxiety agents, etc.). Antihypertensive drugs Sympathomimetic may reduce the effects of antihypertensive drugs. (Brompheniramine, pseudoephedrine, and dextromethorphan label, Drug interactions)

Possible early warning signs of central nervous system (CNS) toxicity are restlessness, anxiety, incoherent speech, lightheadedness, numbness and tingling of the mouth and lips, metallic taste, tinnitus, dizziness, blurred vision, tremors, twitching, CNS depression, or drowsiness. (Bupivacaine label, Warnings and precautions)

…cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine 7.6 Potent Inhalation Anesthetics Serious dose-related cardiac arrhythmias… (Bupivacaine and epinephrine label, Drug interactions)

Warn patients of the potential danger of self-administration of benzodiazepines or other CNS depressants while under treatment with buprenorphine and naloxone sublingual tablets [see Warnings and Precautions (5.3) , Drug Interactions (7) ] . (Buprenorphine and naloxone label, Warnings and precautions)

Other inhibitors and inducers of CYP3A4: Substances that inhibit CYP3A4, such as ketoconazole or ritonavir, may inhibit buspirone metabolism and increase plasma concentrations of buspirone while substances that induce CYP3A4, such as dexamethasone or certain anticonvulsants (phenytoin, phenobarbital, carbamazepine), may increase the rate of buspirone metabolism. (Buspirone label, Drug interactions)

Butalbital and acetaminophen may enhance the effects of:other narcotic analgesics, alcohol, general anesthetics, tranquilizers such as chlordiazepoxide, sedative-hypnotics, or other CNS depressants, causing increased CNS depression. (Butalbital and acetaminophen label, Drug interactions)

Butalbital, acetaminophen and caffeine may enhance the effects of: other narcotic analgesics, alcohol, general anesthetics, tranquilizers such as chlordiazepoxide, sedative-hypnotics, or other CNS depressants, causing increased CNS depression. (Butalbital, acetaminophen, and caffeine label, Drug interactions)

Other narcotic analgesics, alcohol, general anesthetics, tranquilizers such as chlordiazepoxide, sedative-hypnotics, or other CNS depressants, causing increased CNS depression. (Butalbital, aspirin, and caffeine label, Drug interactions)

Phenytoin/Phenobarbital The coadministration of phenytoin or phenobarbital will not affect plasma concentrations of calcitriol, but may reduce endogenous plasma levels of 25(OH)D 3 by accelerating metabolism. (Calcitriol label, Drug interactions)

Examples: Rifampin, phenytoin, phenobarbital, ritonavir Insulin or Insulin Secretagogues Clinical Impact: The risk of hypoglycemia is increased when INVOKANA is used concomitantly with insulin secretagogues (e.g., sulfonylurea) or insulin. (Canagliflozin label, Drug interactions)

Interactions with Hydrochlorothiazide Alcohol, barbiturates, or narcotics − Potentiation of orthostatic hypotension may occur. (Candesartan and hydrochlorothiazide label, Drug interactions)

Other CNS depressants, including alcohol, could potentiate the somnolence and sedation effect of EPIDIOLEX. (Cannabidiol (prescription) label, Warnings and precautions)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system (CNS) pathology. (Carbidopa label, Warnings)

Strenuous exercise, exposure to extreme heat, dehydration, and anticholinergic medications may contribute to an elevation in core body temperature; use VRAYLAR with caution in patient who may experience these conditions. (Cariprazine label, Warnings and precautions)

• Additive sedative effects when used with other CNS depressants including alcohol (5.1) (Carisoprodol label, Warnings and precautions)

Consider alternative drugs to phenobarbital. (Carmustine label, Drug interactions)

Phenobarbital and Clobazam: Reduce dosage as needed when used concomitantly with XCOPRI. (Cenobamate label, Drug interactions)

…procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants Phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine (Chloroprocaine label, Precautions)

Alcohol, Barbiturates, or Narcotics - potentiation of orthostatic hypotension may occur. (Chlorothiazide label, Drug interactions)

Chlorzoxazone use should also be discontinued if a patient develops abnormal liver enzymes (e.g., AST, ALT, alkaline phosphatase and bilirubin.) The concomitant use of alcohol or other central nervous system depressants may have an additive effect. (Chlorzoxazone label, Warnings and precautions)

Drug Interactions Cholestyramine for Oral Suspension USP may delay or reduce the absorption of concomitant oral medication such as phenylbutazone, warfarin, thiazide diuretics (acidic), or propranolol (basic), as well as tetracycline, penicillin G, phenobarbital, thyroid and thyroxine preparations, estrogens and progestins, and digitalis. (Cholestyramine label, Drug interactions)

John’s Wort Use With Caution There have been spontaneous or published reports of CYP3A based interactions of clarithromycin with alfentanil, methylprednisolone, cilostazol, bromocriptine, vinblastine, phenobarbital, and St. (Clarithromycin label, Drug interactions)

Use with CNS Depressants Clemastine has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.). Use in Activities Requiring Mental Alertness Patients should be warned about engaging in activities requiring mental alertness such as driving a car or operating appliances, machinery, etc. (Clemastine label, Warnings)

Administration of CMI has been reported to increase the plasma levels of phenobarbital, if given concomitantly ( see CLINICAL PHARMACOLOGY, Interactions ). (Clomipramine label, Drug interactions)

John's Wort (Hypericum perforatum) preparations, phenobarbital, carbamazepine, and rifampin, may reduce plasma concentrations of some estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile. (Conjugated estrogens and bazedoxifene label, Drug interactions)

John’s Wort rifampin oxcarbazepine octreotide phenobarbital orlistat phenytoin sulfinpyrazone terbinafine ticlopidine Bosentan Coadministration of bosentan (250 to 1000 mg every 12 hours based on tolerability) and cyclosporine (300 mg every 12 hours for 2 days then dosing to achieve a C min of 200 to 250 ng/mL) for 7 days in healthy subjects resulted in decreases… (Cyclosporine label, Drug interactions)

CNS Depressants Antihistamines may have additive effects with alcohol and other CNS depressants, e.g., hypnotics, sedatives, tranquilizers, antianxiety agents. (Cyproheptadine label, Warnings)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

CNS-Depressant Effects and Daytime Impairment: Impairs alertness and motor coordination including morning impairment. (Daridorexant label, Warnings and precautions)

Darifenacin extended-release tablets, like other anticholinergic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as severe constipation, ulcerative colitis, and myasthenia gravis. (Darifenacin label, Warnings and precautions)

The concomitant use of Exjade with potent UGT inducers (e.g., rifampicin, phenytoin, phenobarbital, ritonavir) may result in a decrease in Exjade efficacy due to a possible decrease in deferasirox concentration. (Deferasirox label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St. (Desogestrel and ethinyl estradiol label, Drug interactions)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system pathology. (Deutetrabenazine label, Warnings and precautions)

PRECAUTIONS CORPHENA Oral Solution has an atropine-like action and, therefore, should be used with caution in patients with: History of bronchial asthma Increased intraocular pressure Hyperthyroidism Cardiovascular disease Hypertension Drug Interaction MAO inhibitors prolong and intensify the anticholinergic (drying) effects of antihistamines. (Dexchlorpheniramine label, Precautions)

The intravenous administration of anticholinergic agents (e.g., glycopyrrolate, atropine) should be considered to modify vagal tone. (Dexmedetomidine label, Warnings and precautions)

Anticholinergic effects of quinidine: Monitor for worsening in myasthenia gravis and other sensitive conditions. (Dextromethorphan and quinidine label, Warnings and precautions)

Anticholinergic agents: may affect the gastrointestinal absorption of various drugs; may also increase certain actions or side effects of other anticholinergic drugs (7) (Dicyclomine label, Drug interactions)

The concomitant use of alcohol or other central nervous system depressants may have an additive effect. (Dimenhydrinate label, Warnings)

Drug Interactions Diphenhydramine hydrochloride has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc). (Diphenhydramine label, Drug interactions)

Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance. (Divalproex (valproate) label, Drug interactions)

Potential additive effects when used in combination with CNS depressants or sedating antihistamines. (Doxepin label, Warnings and precautions)

Examples Glutethimide and phenobarbital Intervention If a patient initiates or discontinues therapy with an enzyme inducer, dose adjustment of doxercalciferol may be necessary. (Doxercalciferol label, Drug interactions)

Barbiturates, carbamazepine and phenytoin decrease the half-life of doxycycline. (Doxycycline label, Drug interactions)

Concomitant use of other drugs that cause dizziness, confusion, sedation, or somnolence such as CNS depressants may increase this effect (e.g., barbiturates, benzodiazepines, lithium, opioids, buspirone, scopolamine, antihistamines, tricyclic antidepressants, other anticholinergic agents, and muscle relaxants). (Dronabinol label, Warnings and precautions)

CNS Depressant Drugs: Other CNS depressant drugs (e.g. barbiturates, tranquilizers, opioids and general anesthetics) have additive or potentiating effects with droperidol. (Droperidol label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampin, topiramate and products containing St. (Drospirenone and ethinyl estradiol label, Drug interactions)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Patients who are receiving concomitant anticonvulsant medications primarily metabolized by the liver, such as phenytoin and phenobarbital, may require periodic monitoring of plasma levels [see Drug Interactions ( 7.1 ) ] . (Efavirenz label, Warnings and precautions)

Patients who are receiving concomitant anticonvulsant medications primarily metabolized by the liver, such as phenytoin and phenobarbital, may require periodic monitoring of plasma levels [see Drug Interactions (7.5) ] . (Efavirenz, lamivudine, and tenofovir label, Warnings and precautions)

Examples: alosetron, anticholinergics, opioids Table 3: Established and Other Potentially Clinically Relevant Interactions Affecting Drugs Co-Administered with VIBERZI OATP1B1 and BCRP Substrate Clinical Impact: VIBERZI may increase the exposure of co-administered OATP1B1 and BCRP substrates. (Eluxadoline label, Drug interactions)

Other Agents Anticonvulsants: carbamazepine oxcarbazepine phenobarbital phenytoin ↓ TAF Consider alternative anticonvulsant. (Emtricitabine and tenofovir label, Drug interactions)

Hydrochlorothiazide When administered concurrently the following drugs may interact with thiazide diuretics: Alcohol, barbiturates, or narcotics Potentiation of orthostatic hypotension may occur. (Enalapril and hydrochlorothiazide label, Drug interactions)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Increase the erlotinib dosage if co-administration with CYP3A4 inducers (e.g., carbamazepine, phenytoin, rifampin, rifabutin, rifapentine, phenobarbital and St. (Erlotinib label, Drug interactions)

Phenobarbital or Primidone: Higher dosage of APTIOM may be necessary. (Eslicarbazepine label, Drug interactions)

John's Wort preparations (Hypericum perforatum), phenobarbital, carbamazepine, and rifampin may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile. (Estradiol label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampin, topiramate and products containing St. (Estradiol and dienogest label, Drug interactions)

John's wort ( Hypericum perforatum ) preparations, phenobarbital, carbamazepine, and rifampin may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile. (Estradiol and norethindrone label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include: phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St. (Etonogestrel and ethinyl estradiol label, Drug interactions)

CBZ epoxide ↓ ↑ ↓ Phenobarbital ↑ ↓ Specific Effects of Felbatol® on Other Antiepileptic Drugs Phenytoin Felbatol ® causes an increase in steady-state phenytoin plasma concentrations. (Felbamate label, Drug interactions)

Anticonvulsants - In a pharmacokinetic study, maximum plasma concentrations of felodipine were considerably lower in epileptic patients on long-term anticonvulsant therapy (e.g., phenytoin, carbamazepine, or phenobarbital) than in healthy volunteers. (Felodipine label, Drug interactions)

Phenobarbital Clinical Impact: Chronic administration of phenobarbital, a known enzyme inducer, may be associated with a decrease in the plasma half-life of fenoprofen. (Fenoprofen label, Drug interactions)

Urinary Retention in Adult Patients With Bladder Outlet Obstruction The use of Toviaz, like other antimuscarinic drugs, in patients with clinically significant bladder outlet obstruction, including patients with urinary retention, may result in further urinary retention and kidney injury. (Fesoterodine label, Warnings and precautions)

Limited data in patients receiving known enzyme inducers ( phenytoin, phenobarbital, carbamazepine ) indicate only a 30% increase in the rate of flecainide elimination. (Flecainide label, Drug interactions)

Exacerbated by other CNS depressants, and in settings where flibanserin concentrations are increased. (Flibanserin label, Warnings and precautions)

Barbiturates, phenytoin, or rifampin —increased metabolic clearance of fludrocortisone acetate because of the induction of hepatic enzymes. (Fludrocortisone label, Drug interactions)

Possible risk factors for seizures include: concurrent major sedative-hypnotic drug withdrawal, recent therapy with repeated doses of parenteral benzodiazepines, myoclonic jerking or seizure activity prior to flumazenil administration in overdose cases, or concurrent cyclic antidepressant poisoning. (Flumazenil label, Warnings)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. (Fluphenazine label, Warnings)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

John's wort may vary widely based on preparation. theophylline Drugs that may either increase or decrease phenytoin serum levels Antiepileptic drugs Phenobarbital, valproate sodium, valproic acid 7.2 Drugs Affected by Phenytoin or CEREBYX Table 7 includes commonly occurring drug interactions affected by phenytoin (the active metabolite of CEREBYX). (Fosphenytoin label, Drug interactions)

…including glimepiride, leading to worsening glycemic control: danazol, glucagon, somatropin, protease inhibitors, atypical antipsychotic medications (e.g., olanzapine and clozapine), barbiturates, diazoxide, laxatives, rifampin, thiazides and other diuretics, corticosteroids, phenothiazines, thyroid hormones, estrogens, oral contraceptives, phenytoin, nicotinic… (Glimepiride label, Drug interactions)

In a human pharmacokinetic study, hepatic enzyme induction with phenobarbital resulted in a 25% increase in total plasma clearance of intravenous granisetron hydrochloride. (Granisetron label, Drug interactions)

Barbiturates usually depress griseofulvin activity by decreasing plasma levels and concomitant administration may require a dosage adjustment of the antifungal agent. (Griseofulvin label, Drug interactions)

Consider the potential for additive sedative effects with CNS depressant drugs. (Guanfacine label, Warnings and precautions)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. (Haloperidol label, Warnings)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Strenuous exercise, exposure to extreme heat, dehydration, and anticholinergic medications may contribute to an elevation in core body temperature; use FANAPT with caution in patients who may experience these conditions. (Iloperidone label, Warnings and precautions)

Imipramine hydrochloride may enhance the CNS depressant effects of alcohol. (Imipramine label, Warnings)

Because of its anticholinergic effects, XEOMIN should be used with caution in patients at risk of developing narrow angle glaucoma. (IncobotulinumtoxinA label, Warnings and precautions)

Carbamazepine, phenytoin, phenobarbital, primidone, and rifampin decrease lamotrigine concentrations by approximately 40%. (Lamotrigine label, Drug interactions)

Anticonvulsants: carbamazepine phenytoin phenobarbital ↓ ledipasvir ↓ sofosbuvir Coadministration of ledipasvir and sofosbuvir with carbamazepine, phenytoin, or phenobarbital is expected to decrease the concentration of ledipasvir and sofosbuvir, leading to reduced therapeutic effect of ledipasvir and sofosbuvir. (Ledipasvir and sofosbuvir label, Drug interactions)

CNS Depressant Effects and Daytime Impairment: Impairs alertness and motor coordination including morning impairment. (Lemborexant label, Warnings and precautions)

Folic acid in high doses may reduce the effectiveness of certain antiepileptic drugs (e.g., phenobarbital, phenytoin, and primidone) and thereby increase the frequency of seizures. (Leucovorin label, Drug interactions)

Effects of Leucovorin Products on Other Drugs Antiepileptic Drugs Folic acid in large amounts may counteract the antiepileptic effect of phenobarbital, phenytoin and primidone and increase the frequency of seizures in susceptible children. (Levoleucovorin label, Drug interactions)

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine. (Levothyroxine label, Drug interactions)

…cyclophosphamide, flutamide, hydroxyurea, isofamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine 7.6 Potent Inhalation Anesthetics Serious dose-related cardiac arrhythmias… (Lidocaine and epinephrine label, Drug interactions)

…prilocaine, procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea, isofamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sufonamides Antimalarials chloroquine, primaquine Anticonvulsants Phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine (Lidocaine and prilocaine label, Drug interactions)

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine. (Liothyronine label, Drug interactions)

Alcohol, barbiturates, or narcotics - potentiation of orthostatic hypotension may occur. (Lisinopril and hydrochlorothiazide label, Drug interactions)

Increased Risk of CNS Depression with Concomitant use of CNS Depressant Drugs : Lofexidine tablets potentiates the CNS depressant effects of benzodiazepines and may potentiate the CNS depressant effects of alcohol, barbiturates, and other sedating drugs. (Lofexidine label, Warnings and precautions)

• Coadministration of meclizine hydrochloride with other CNS depressants, including alcohol, may result in increased CNS depression ( 7.1 ). (Meclizine label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include: • barbiturates • bosentan • carbamazepine • felbamate • griseofulvin • oxcarbazepine • phenytoin • rifampin • St. (Medroxyprogesterone label, Drug interactions)

Anticonvulsants In patients taking an anticonvulsant (e.g., valproic acid, carbamazepine, phenobarbital or phenytoin), the concomitant use of mefloquine may reduce seizure control by lowering the plasma levels of the anticonvulsant. (Mefloquine label, Drug interactions)

Inducers of CYP3A4 (e.g., phenytoin, carbamazepine, dexamethasone, rifampin, and phenobarbital) could increase the rate of elimination of donepezil. (Memantine and donepezil label, Drug interactions)

…procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine (Mepivacaine label, Drug interactions)

Additive Effects Since the effects of meprobamate and alcohol or meprobamate and other CNS depressants or psychotropic drugs may be additive,appropriate caution should be exercised with patients who take more than one of these agents simultaneously. (Meprobamate label, Warnings)

ATMEKSI may potentiate the effects of CNS (central nervous system) depressants and alcohol ( 5.1 ) (Methocarbamol label, Warnings and precautions)

Drug Interactions Since Celontin (methsuximide) may interact with concurrently administered antiepileptic drugs, periodic serum level determinations of these drugs may be necessary (eg, methsuximide may increase the plasma concentrations of phenytoin and phenobarbital). (Methsuximide label, Drug interactions)

Hepatic Enzyme Inducers (e.g., barbiturates, phenytoin, carbamazepine, rifampin) : Drugs which induce cytochrome P450 3A4 enzyme activity may enhance the metabolism of corticosteroids and require that the dosage of the corticosteroid be increased. (Methylprednisolone label, Drug interactions)

Alcohol, Barbiturates, And Narcotics The hypotensive effects of these drugs may be potentiated by the volume contraction that may be associated with metolazone therapy. (Metolazone label, Drug interactions)

Inducers of CYP450 Liver Enzymes The simultaneous administration of LIKMEZ and drugs that induce microsomal liver enzymes, such as phenytoin or phenobarbital, may accelerate the elimination of metronidazole, resulting in reduced plasma concentrations of metronidazole. (Metronidazole label, Drug interactions)

Concurrent use of metyrosine with alcohol or other CNS depressants can increase their sedative effects. (Metyrosine label, Drug interactions)

• Urinary Retention in Patients With Bladder Outlet Obstruction and in Patients Taking Muscarinic Antagonist Drugs for Overactive Bladder : Administer with caution in these patients because of risk of urinary retention. (Mirabegron label, Warnings and precautions)

WARNINGS AND PRECAUTIONS Risk of Recurrent Respiratory and CNS Depression : Due to the duration of action of naloxone relative to the opioid, respiratory and CNS depression may recur after the first dose of naloxone. (Naloxone label, Warnings and precautions)

Bradycardia : Atropine or glycopyrrolate should be administered prior to administration of neostigmine methylsulfate injection to lessen risk of bradycardia ( 5.1 ) (Neostigmine label, Warnings and precautions)

Alternative antihypertensive therapy should be considered in patients taking phenytoin, phenobarbital, and carbamazepine. (Nifedipine label, Precautions)

Possible Reduced Efficacy with Strong CYP3A4 Inducers Concomitant use of strong CYP3A4 inducers (e.g., carbamazepine, phenobarbital, phenytoin, rifampin, St. (Nimodipine label, Warnings and precautions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St. (Norelgestromin and ethinyl estradiol label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of HCs include efavirenz, phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, rifabutin, rufinamide, aprepitant, and products containing St. (Norethindrone label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include: barbiturates bosentan carbamazepine felbamate griseofulvin oxcarbazepine phenytoin rifampin St. (Norethindrone and ethinyl estradiol label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St. (Norgestimate and ethinyl estradiol label, Drug interactions)

Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate rifabutin, rufinamide, aprepitant, and products containing St. (Norgestrel and ethinyl estradiol label, Drug interactions)

Close supervision and careful adjustment of the dosage are required when Pamelor is used with other anticholinergic drugs and sympathomimetic drugs. (Nortriptyline label, Drug interactions)

Anticholinergic (antimuscarinic) Effects: Use with caution with other anticholinergic drugs and in patients with urinary retention, prostatic hypertrophy, constipation, paralytic ileus or related conditions. (Olanzapine label, Warnings and precautions)

Anticholinergic (antimuscarinic) Effects : Use with caution with other anticholinergic drugs and in patients with urinary retention, prostatic hypertrophy, constipation, history of paralytic ileus or related conditions ( 5.21 ) (Olanzapine and fluoxetine label, Warnings and precautions)

Anticholinergic Drugs Use of anticholinergic drugs after administration of BOTOX may potentiate systemic anticholinergic effects. (OnabotulinumtoxinA label, Drug interactions)

Carbamazepine, Phenytoin, and Phenobarbital: Decreased plasma levels of MHD (the active metabolite). (Oxcarbazepine label, Drug interactions)

Oxybutynin chloride extended-release tablets, like other anticholinergic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as ulcerative colitis and intestinal atony. (Oxybutynin label, Warnings and precautions)

Patients should be carefully observed for signs of central nervous system (CNS) depression, such as somnolence and sedation, when FYCOMPA is used with other drugs with sedative properties because of potential additive effects. (Perampanel label, Warnings and precautions)

The concomitant use of alcohol or central nervous system (CNS) depressant drugs with phentermine and topiramate extended-release capsules may potentiate CNS depression or other centrally mediated effects of these agents, such as dizziness, cognitive adverse reactions, drowsiness, light-headedness, impaired coordination, and somnolence. (Phentermine and topiramate label, Warnings and precautions)

Agonistic Effects (increase in BIORPHEN blood pressure effect) can occur with monoamine oxidase inhibitors (MAOI), oxytocin and oxytocic drugs, tricyclic antidepressants, angiotensin and aldosterone, atropine, steroids, norepinephrine transporter inhibitors, ergot alkaloids. (Phenylephrine label, Drug interactions)

John’s wort may vary widely based on preparation. , sucralfate, theophylline Drugs that may either increase or decrease phenytoin serum levels Antiepileptic drugs Phenobarbital, valproate sodium Valproate sodium and valproic acid are similar medications. (Phenytoin label, Drug interactions)

These effects should be considered when anticholinergic properties may be contributing to the therapeutic effect of concomitant medication (e.g., atropine, inhaled ipratropium). (Pilocarpine label, Drug interactions)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. (Pimozide label, Warnings)

…including glimepiride, leading to worsening glycemic control: danazol, glucagon, somatropin, protease inhibitors, atypical antipsychotic medications (e.g., olanzapine and clozapine), barbiturates, diazoxide, laxatives, rifampin, thiazides and other diuretics, corticosteroids, phenothiazines, thyroid hormones, estrogens, oral contraceptives, phenytoin, nicotinic… (Pioglitazone and glimepiride label, Drug interactions)

Concomitant Use with Midazolam : Noxafil can prolong hypnotic/sedative effects. (Posaconazole label, Warnings and precautions)

CYP 3A4 inducers (e.g. barbiturates, phenytoin, carbamazepine, and rifampin): Drugs such as barbiturates, phenytoin, ephedrine, and rifampin, which induce hepatic microsomal drug metabolizing enzyme activity may enhance metabolism of prednisolone and require that the dosage of Orapred be increased. (Prednisolone label, Drug interactions)

CYP 3A4 Inducers (e.g., Barbiturates, Phenytoin, Carbamazepine, and Rifampin) Drugs such as barbiturates, phenytoin, ephedrine, and rifampin, which induce hepatic microsomal drug metabolizing enzyme activity may enhance the metabolism of corticosteroids and require that the dosage of the corticosteroid be increased. (Prednisone label, Drug interactions)

…cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine The administration of local anesthetic injections containing epinephrine… (Prilocaine and epinephrine label, Drug interactions)

Anticholinergic drugs administered concurrently with PA may produce additive antivagal effects on A-V nodal conduction, although this is not as well documented for PA as for quinidine. (Procainamide label, Drug interactions)

The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine… (Promethazine label, Warnings)

The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine… (Promethazine and dextromethorphan label, Warnings)

The intravenous administration of anticholinergic agents (e.g., atropine or glycopyrrolate) should be considered to modify potential increases in vagal tone due to concomitant agents (e.g., succinylcholine) or surgical stimuli. (Propofol label, Warnings and precautions)

Protriptyline may enhance the response to alcohol and the effects of barbiturates and other CNS depressants. (Protriptyline label, Drug interactions)

• Anticholinergic (antimuscarinic) Effects: Use with caution with other anticholinergic drugs and in patients with urinary retention, prostatic hypertrophy, or constipation (5.20) (Quetiapine label, Warnings and precautions)

The use of alcohol and other CNS depressants may increase the risk of such behaviors. (Ramelteon label, Warnings and precautions)

…ciprofloxacin) Oral Anticoagulants Warfarin Anticonvulsants Phenytoin Antimalarials Quinine Azole Antifungals Fluconazole, itraconazole, ketoconazole Antipsychotics Haloperidol Barbiturates Phenobarbital Benzodiazepines Diazepam Beta-Blockers Propranolol Calcium Channel Blockers Diltiazem, nifedipine, verapamil Cardiac Glycoside Preparations Digoxin Corticosteroids Prednisone… (Rifapentine label, Drug interactions)

Co-administration of other known CYP 3A4 enzyme inducers (e.g., phenytoin, rifampin, and phenobarbital) with risperidone may cause similar decreases in the combined plasma concentrations of risperidone and 9-hydroxyrisperidone, which could lead to decreased efficacy of RISPERDAL CONSTA treatment. (Risperidone label, Drug interactions)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

…cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants Phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine NAROPIN should be used with caution in patients receiving other local anesthetics… (Ropivacaine label, Drug interactions)

…Influence of AED on Rufinamide concentration Carbamazepine Decrease by 7 to 13% b) Decrease by 19 to 26% Dependent on dose of carbamazepine Lamotrigine Decrease by 7 to 13% b) No Effect Phenobarbital Increase by 8 to 13% b) Decrease by 25 to 46% c) ’ d) Independent of dose or concentration of phenobarbital Phenytoin Increase by 7 to 21% b) Decrease by 25 to 46% c)… (Rufinamide label, Drug interactions)

Inhibitors of Folate Synthesis (e.g., methotrexate, valproic acid, phenobarbital, trimethoprim) Clinical Impact In vitro and in vivo nonclinical data suggest that drugs that inhibit folate synthesis may decrease the bioavailability of endogenous BH4 by inhibiting the enzyme dihydrofolate reductase, which is involved in the recycling (regeneration) of BH4. (Sapropterin label, Drug interactions)

• Gastrointestinal and Urinary Disorders : Consider more frequent monitoring during treatment in patients suspected of having intestinal obstruction; patients with pyloric obstruction, patients with impeded urine flow or receiving other anticholinergic drugs. (Scopolamine label, Warnings and precautions)

Drugs that induce CYP3A4 (e.g., phenytoin, carbamazepine, nafcillin, phenobarbital, and rifampin) should be used with caution. (Selegiline label, Drug interactions)

Consider having an anticholinergic and epinephrine available when administering sevoflurane for induction in this patient population. (Sevoflurane label, Warnings)

…clotrimazole, danazol, diltiazem, fluconazole, letermovir, protease inhibitors (e.g., HIV and hepatitis C that include drugs such as ritonavir, indinavir, boceprevir, and telaprevir), metoclopramide, nicardipine, troleandomycin, verapamil • Drugs and other agents that could decrease sirolimus concentrations: Carbamazepine, phenobarbital, phenytoin, rifapentine, St. (Sirolimus label, Drug interactions)

Urinary Retention The use of Solifenacin succinate tablets, like other antimuscarinic drugs, in patients with clinically significant bladder outlet obstruction including patients with urinary retention, may result in further urinary retention and kidney injury. (Solifenacin label, Warnings and precautions)

Alcohol, barbiturates, or narcotics: Potentiation of orthostatic hypotension may occur. (Spironolactone and hydrochlorothiazide label, Drug interactions)

Pretreatment with anticholinergic agents (e.g., atropine) may reduce the occurrence of bradyarrhythmias. (Succinylcholine label, Warnings and precautions)

Monitor for hemodynamic changes and administer anticholinergic agents such as atropine if clinically significant bradycardia is observed. (Sugammadex label, Warnings and precautions)

CNS Depressant Effects and Daytime Impairment: Risk of impaired alertness and motor coordination, including impaired driving; risk increases with dose; caution patients taking 20 mg against next-day driving and other activities requiring complete mental alertness ( 5.1 ). (Suvorexant label, Warnings and precautions)

Strong CYP3A Inducers c : Antimycobacterials (e.g., rifampin, rifabutin), anticonvulsants (e.g., phenytoin, carbamazepine and phenobarbital), St John’s wort May decrease tacrolimus whole blood trough concentrations and increase the risk of rejection [see Warnings and Precautions ( 5.10 )]. (Tacrolimus label, Drug interactions)

Although specific interactions have not been studied, other CYP3A4 inducers, such as carbamazepine, phenytoin, and phenobarbital, would likely decrease tadalafil exposure. (Tadalafil label, Drug interactions)

Co-administration with Inducers or Inhibitors of CYP3A Metabolism Agents Inducing CYP3A Metabolism: Strong inducers of CYP3A4/5 such as dexamethasone, carbamazepine, phenytoin, phenobarbital, rifampin, rifabutin, and rifampacin may decrease exposure of the active metabolite, sirolimus. (Temsirolimus label, Warnings and precautions)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system pathology. (Tetrabenazine label, Warnings and precautions)

30% increase Phenobarbital (PB) Similar to aminoglutethimide. (Theophylline label, Drug interactions)

Severe respiratory depression and respiratory arrest have been reported when a patient was given a phenothiazine and a concomitant high dose of a barbiturate. (Thioridazine label, Warnings)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. (Thiothixene label, Warnings)

Sedation: Zanaflex may interfere with everyday activities; sedative effects of Zanaflex, alcohol, and other central nervous system (CNS) depressants are additive ( 5.3 , 7.4 ) (Tizanidine label, Warnings and precautions)

Caution should be used when topiramate extended-release capsules are prescribed with other drugs that predispose patients to heat-related disorders; these drugs include, but are not limited to, other carbonic anhydrase inhibitors and drugs with anticholinergic activity. (Topiramate label, Warnings and precautions)

CNS Depressants: RALDESY may enhance effects of alcohol, barbiturates, or other CNS depressants ( 7 ). (Trazodone label, Drug interactions)

Hepatic enzyme inducers (e.g., barbiturates, phenytoin, carbamazepine, rifampin): Drugs which induce hepatic microsomal drug metabolizing enzyme activity may enhance the metabolism of corticosteroids and require that the dosage of the corticosteroid be increased. (Triamcinolone label, Drug interactions)

Trihexyphenidyl should be administered with caution in hot weather, especially when given concomitantly with other atropine-like drugs to the chronically ill, alcoholics, those who have central nervous system disease, or those who do manual labor in a hot environment. (Trihexyphenidyl label, Warnings)

The recent use of other drugs that cause CNS depression or EPS symptoms may also increase the risk; consider reducing the dosage or discontinuing the drug. (Trimethobenzamide label, Warnings and precautions)

Trospium chloride extended-release capsules, like other antimuscarinic agents, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as ulcerative colitis, intestinal atony and myasthenia gravis. (Trospium label, Warnings and precautions)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system pathology. (Valbenazine label, Warnings and precautions)

Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance. (Valproic acid label, Drug interactions)

Thiopental Reconstituted vecuronium, which has an acid pH, should not be mixed with alkaline solutions (e.g., barbiturate solutions such as thiopental) in the same syringe or administered simultaneously during intravenous infusion through the same needle or through the same intravenous line (see DOSAGE AND ADMINISTRATION -COMPATIBILITY ). (Vecuronium label, Precautions)

Phenobarbital Phenobarbital therapy may increase verapamil clearance. (Verapamil label, Drug interactions)

Urinary Retention : Monitor for urinary retention, especially in patients with bladder outlet obstruction and also in patients taking muscarinic antagonist medications for OAB, in whom the risk of urinary retention may be greater. (Vibegron label, Warnings and precautions)

Phenobarbital may decrease the effect of anticoagulants, and necessitate larger doses of the anticoagulant for optimal effect. (Phenobarbital, hyoscyamine, atropine, and scopolamine label, Warnings)

Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system (CNS) pathology. (Ziprasidone label, Warnings and precautions)

Caution should be used when ZONISADE is prescribed with other drugs that predispose patients to heat-related disorders; these drugs include, but are not limited to, carbonic anhydrase inhibitors and drugs with anticholinergic activity. (Zonisamide label, Warnings and precautions)

Concomitant taking of P-gp inducers (including but not limited to rifampicin, carbamazepine, phenytoin, phenobarbital, and St. (Afatinib label, Drug interactions)

Guanethidine or similarly acting compounds; thyroid medication; alcohol, barbiturates and other CNS depressants; and disulfiram – see WARNINGS section. (Amitriptyline label, Drug interactions)

Atracurium besylate injection, which has an acid pH, should not be mixed with alkaline solutions (e.g., barbiturate solutions) in the same syringe or administered simultaneously during intravenous infusion through the same needle. (Atracurium label, Warnings)

Co-administration of INLYTA with strong CYP3A4/5 inducers (e.g., rifampin, dexamethasone, phenytoin, carbamazepine, rifabutin, rifapentine, phenobarbital, and St. (Axitinib label, Drug interactions)

Cevimeline might interfere with desirable antimuscarinic effects of drugs used concomitantly. (Cevimeline label, Drug interactions)

…Probenecid Probenecid is known to interact with the metabolism or renal tubular excretion of many drugs (e.g., acetaminophen, acyclovir, angiotensin-converting enzyme inhibitors, aminosalicylic acid, barbiturates, benzodiazepines, bumetanide, clofibrate, methotrexate, famotidine, furosemide, nonsteroidal anti-inflammatory agents, theophylline, and zidovudine). (Cidofovir label, Drug interactions)

Phenobarbital Amphetamines may delay intestinal absorption of phenobarbital; co-administration of phenobarbital may produce a synergistic anticonvulsant action. (Dextroamphetamine label, Drug interactions)

Drug Interactions There was no evidence of drug interactions in clinical studies in which dobutamine was administered concurrently with other drugs, including digitalis preparations, furosemide, spironolactone, lidocaine, glyceryl trinitrate, isosorbide dinitrate, morphine, atropine, heparin, protamine, potassium chloride, folic acid, and acetaminophen. (Dobutamine label, Drug interactions)

Use alternative treatment that does not include carbamazepine where possible for INSTI-experienced patients with certain INSTI-associated resistance substitutions or clinically suspected INSTI resistance. b Oxcarbazepine Phenytoin Phenobarbital St. (Dolutegravir label, Drug interactions)

Cholinesterase inhibitors have the potential to interfere with the activity of anticholinergic medications ( 7.1 ) (Donepezil label, Drug interactions)

In Drug-Induced CNS and Respiratory Depression Doxapram alone may not stimulate adequate spontaneous breathing or provide sufficient arousal in patients who are severely depressed either due to respiratory failure or to CNS depressant drugs, but may be used as an adjunct to established supportive measures and resuscitative techniques. (Doxapram label, Warnings)

Examples of strong CYP3A inducers include: rifampin, rifabutin, phenobarbital, carbamazepine, phenytoin and St. (Elexacaftor, tezacaftor, and ivacaftor label, Drug interactions)

Clonidine, propofol, monoamine oxidase inhibitors (MAOIs), atropine C linical Impact: These drugs augment the pressor effect of ephedrine. (Ephedrine label, Drug interactions)

The “gasping syndrome” is characterized by central nervous system (CNS) depression, metabolic acidosis, and gasping respirations. (Epoetin alfa label, Warnings and precautions)

Data are more extensive with respect to phenytoin and phenobarbital, but these are also the most commonly prescribed anticonvulsants; less systematic or anecdotal reports suggest a possible similar association with the use of all known anticonvulsant drugs. (Ethosuximide label, Warnings)

A similar association, though less marked, has been suggested for barbiturates, phenylbutazone, phenytoin sodium, and possibly with griseofulvin, ampicillin, and tetracyclines. (Ethynodiol diacetate and ethinyl estradiol label, Drug interactions)

Drugs That Induce CYP 3A4 Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. (Exemestane label, Drug interactions)

The conduction abnormalities were usually transient and asymptomatic, and resolved within the first 24 hours on treatment, but they occasionally required treatment with atropine or isoproterenol. (Fingolimod label, Warnings and precautions)

Potential to interfere with the activity of anticholinergic medications ( 7.1 ) (Galantamine label, Drug interactions)

Examples: Anticonvulsants: phenytoin, carbamazepine and oxcarbazepine Antibiotics: rifampicin and rifabutin Barbiturates: phenobarbital and primidone Antiretrovirals: efavirenz and nevirapine Estrogen and Estrogen Containing Products Clinical Impact: Oral estrogen and estrogen-containing oral contraceptives may interact with hydrocortisone by increasing serum… (Hydrocortisone label, Drug interactions)

John’s wort, rifampicin, barbiturates, and phenytoin [ s ee Clinical Pharmacology ( 12.3 )] . (Ivabradine label, Drug interactions)

Therefore, co-administration with strong CYP3A inducers, such as rifampin, rifabutin, phenobarbital, carbamazepine, phenytoin, and St. (Ivacaftor label, Drug interactions)

Other Antiepileptic Drugs Potential drug interactions between levetiracetam and other AEDs (carbamazepine, gabapentin, lamotrigine, phenobarbital, phenytoin, primidone and valproate) were also assessed by evaluating the serum concentrations of levetiracetam and these AEDs during placebo-controlled clinical studies. (Levetiracetam label, Drug interactions)

Examples Aprepitant, barbiturates, bosentan, carbamazepine, efavirenz, felbamate, griseofulvin, oxcarbazepine, phenytoin, rifampin, primidone, phenylbutazone, rifabutin, rufinamide, topiramate, products containing St. (Levonorgestrel and ethinyl estradiol label, Drug interactions)

Strenuous exercise, exposure to extreme heat, dehydration, and anticholinergic drugs may contribute to an elevation in core body temperature. (Lumateperone label, Warnings and precautions)

Appropriate care is advised when prescribing LATUDA for patients who will be experiencing conditions that may contribute to an elevation in core body temperature, e.g., exercising strenuously, exposure to extreme heat, receiving concomitant medication with anticholinergic activity, or being subject to dehydration. (Lurasidone label, Warnings and precautions)

Apnea/hypoventilation may be noted during induction, which may impair pulmonary ventilation; the duration of apnea may be longer than that produced by other barbiturate anesthetics. (Methohexital label, Warnings)

When phenytoin or other hepatic enzyme inducers such as rifampin and phenobarbital have been taken concurrently with mexiletine, lowered mexiletine plasma levels have been reported. (Mexiletine label, Drug interactions)

Appropriate care is advised when prescribing ERZOFRI to patients who will be experiencing conditions which may contribute to an elevation in core body temperature, e.g., exercising strenuously, exposure to extreme heat, receiving concomitant medication with anticholinergic activity, or being subject to dehydration. (Paliperidone label, Warnings and precautions)

…glycosides– digitalis and digoxin; (2) hypoglycemics–insulin, chlorpropamide, phenformin, tolazamide, and tolbutamide; (3) tranquilizers and sedatives–chlordiazepoxide, diazepam, and phenobarbital; (4) antigout–allopurinol, colchicine, and probenecid; (5) antiarrhythmics–procainamide, propranolol (see WARNINGS however), and quinidine; and (6) analgesics, antipyretics… (Prazosin label, Drug interactions)

The impact of other inducers of drug metabolizing enzymes, such as phenytoin and phenobarbital, on UGT1A1 is unknown. (Raltegravir label, Drug interactions)

Examples: Drugs that induce the CYP3A4 and/or 2C8 enzyme systems include rifampin, barbiturates, and carbamezapine. (Repaglinide label, Drug interactions)

Strong CYP3A inducers: Strong inducers of CYP3A (for example, rifampin, phenytoin, carbamazepine, phenobarbital or St. (Riociguat label, Drug interactions)

Incompatibility with Alkaline Solutions Rocuronium Bromide Injection, which has an acid pH, should not be mixed with alkaline solutions (e.g., barbiturate solutions) in the same syringe or administered simultaneously during intravenous infusion through the same needle. (Rocuronium label, Warnings and precautions)

CYP3A4 Inducers No information is available on the quantitative effects of CYP3A4 inducers ( e.g., carbamazepine, phenobarbital, phenytoin, fosphenytoin, primidone, rifampicin, St. (Telmisartan and amlodipine label, Drug interactions)

…tiagabine HCl dosing recommendations in current labeling for treatment of epilepsy were based on use in patients with partial seizures 12 years of age and older, most of whom were taking enzyme-inducing antiepileptic drugs (AEDs; e.g., carbamazepine, phenytoin, primidone and phenobarbital) which lower plasma levels of tiagabine HCl by inducing its metabolism. (Tiagabine label, Warnings)

Potential Effects of Other Drugs on Tinidazole CYP3A4 Inducers and Inhibitors: Simultaneous administration of tinidazole with drugs that induce liver microsomal enzymes, i.e., CYP3A4 inducers such as phenobarbital, rifampin, phenytoin, and fosphenytoin (a pro-drug of phenytoin), may accelerate the elimination of tinidazole, decreasing the plasma level of tinidazole. (Tinidazole label, Drug interactions)

It is difficult to determine if Tolcapone tablets played a role in the pathogenesis of these events because these patients received several concomitant medications affecting the central nervous system such as monoaminergic (i.e., MAO-I, tricyclic and selective serotonin reuptake inhibitors) and anticholinergic agents. (Tolcapone label, Precautions)

Effect of Strong CYP3A4 Inducers on Toremifene Strong CYP3A4 enzyme inducers, such as dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, phenobarbital, St. (Toremifene label, Drug interactions)

Similarly, atropine-like effects may be more pronounced in patients receiving anticholinergic therapy. (Trimipramine label, Drug interactions)

In patients taking strong CYP3A4 inducers (e.g., phenytoin, barbiturates, rifampin, St. (Ubrogepant label, Drug interactions)

Drug Interactions No clinically significant drug interactions have been found in studies of losartan potassium with hydrochlorothiazide, digoxin, warfarin, cimetidine and phenobarbital. (Losartan label, Drug interactions)

…adjustment is needed when SINGULAIR is co-administered with theophylline, prednisone, prednisolone, oral contraceptives, fexofenadine, digoxin, warfarin, gemfibrozil, itraconazole, thyroid hormones, sedative hypnotics, non-steroidal anti-inflammatory agents, benzodiazepines, decongestants, and Cytochrome P450 (CYP) enzyme inducers [see Clinical Pharmacology (12.3) ]. (Montelukast label, Drug interactions)

Commonly Administered Drugs: Population analysis showed that commonly administered drugs (e.g., selegiline, amantadine, tricyclic antidepressants, benzodiazepines, ibuprofen, thiazides, antihistamines, anticholinergics) did not affect the clearance of ropinirole. (Ropinirole label, Drug interactions)