Quinidine interactions

Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex. (Acetaminophen and codeine 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)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

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 use of DYANAVEL XR with other serotonergic drugs or CYP2D6 inhibitors is clinically warranted, initiate DYANAVEL XR with lower doses, monitor patients for the emergence of serotonin syndrome during drug initiation or titration, and inform patients of the increased risk for serotonin syndrome. (Amphetamine label, Warnings and precautions)

If serotonin syndrome occurs, discontinue ADDERALL XR and the CYP2D6 inhibitor [see Warnings and Precautions ( 5.8 ), Overdosage ( 10 )] . (Amphetamine and dextroamphetamine label, Drug interactions)

The use of SAPHRIS should be avoided in combination with other drugs known to prolong QTc including Class 1A antiarrhythmics (e.g., quinidine, procainamide) or Class 3 antiarrhythmics (e.g., amiodarone, sotalol), antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine), and antibiotics (e.g., gatifloxacin, moxifloxacin). (Asenapine 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)

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

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

This risk which can be fatal should be considered in patients with certain cardiovascular disorders including known QT prolongation or history torsades de pointes, those with proarrhythmic conditions, and with other drugs that prolong the QT interval. (Azithromycin label, Warnings and precautions)

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

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

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

Examples: paroxetine, fluoxetine, bupropion, quinidine Benzodiazepines and Other Central Nervous System (CNS) Depressants Clinical Impact: Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants, including alcohol, can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death. (Butalbital, acetaminophen, caffeine, and codeine label, Drug interactions)

Examples paroxetine, fluoxetine, bupropion, quinidine Benzodiazepines and other Central Nervous System (CNS) Depressants Clinical Impact: Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants including alcohol, increases the risk of respiratory depression, profound sedation, coma, and death. (Butalbital, aspirin, caffeine, and codeine label, Drug interactions)

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

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

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

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

Avoid use in patients with known prolongation, those with hypokalemia, and with other drugs that prolong the QT interval. (Ciprofloxacin label, Warnings and precautions)

QT Prolongation : Avoid clarithromycin tablets in patients with known QT prolongation or receiving drugs known to prolong the QT interval, ventricular arrhythmia ( torsades de pointes ), hypokalemia/hypomagnesemia, significant bradycardia, or taking Class IA or III antiarrhythmics ( 5.2 ) (Clarithromycin label, Warnings and precautions)

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

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

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

Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex. (Codeine label, Boxed warning)

P-glycoprotein The concomitant use of colchicine capsules and inhibitors of P-glycoprotein (e.g. clarithromycin, ketoconazole, cyclosporine, etc.) should be avoided due to the potential for serious and life-threatening toxicity [see Warnings and Precautions (5.3) and Clinical Pharmacology (12) ] . (Colchicine label, Drug interactions)

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

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

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

Avoid use of PRADAXA Capsules and P-gp inhibitors in patients with severe renal impairment (CrCl 15-30 mL/min) [see Drug Interactions (7.1) and Use in Specific Populations (8.6) ] . (Dabigatran label, Warnings and precautions)

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

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

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

If serotonin syndrome occurs, discontinue dextroamphetamine sulfate and the CYP2D6 inhibitor [see Warnings , Overdosage ]. (Dextroamphetamine label, Drug interactions)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

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

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

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

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Concomitant use of COMPLERA with drugs with a known risk to prolong the QTc interval of the electrocardiogram may increase the risk of Torsade de Pointes. (Emtricitabine, rilpivirine, and tenofovir label, Warnings and precautions)

…such as propranolol Cyclopropane or halogenated hydrocarbon anesthetics, such as halothane Antihistamines Thyroid hormones Diuretics Cardiac glycosides, such as digitalis glycosides Quinidine Drugs potentiating hypokalemic effects of epinephrine • Potassium depleting diuretics • Corticosteroids • Theophylline Epinephrine should not be used to counteract circulatory… (Epinephrine label, Drug interactions)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Strong CYP3A inhibitor and P-gp inhibitor : Avoid coadministration. (Everolimus label, Drug interactions)

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

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Use of quinidine has been associated with QT prolongation and rare occurrences of torsade de pointes. (Fluconazole label, Drug interactions)

Fosamprenavir calcium is contraindicated when coadministered with the following drugs: Alpha 1-adrenoreceptor antagonist: Alfuzosin Antiarrhythmics: Flecainide (with ritonavir ), propafenone (with ritonavir ) Antimycobacterial: Rifampin Antipsychotic: Lurasidone (with ritonavir ), pimozide Ergot derivatives: Dihydroergotamine, ergonovine, ergotamine, methylergonovine… (Fosamprenavir label, Contraindications)

(See DOSAGE and ADMINISTRATION. ) Because of the risk of QT prolongation and the potential for torsades de pointes, the use of FOSCAVIR should be avoided in combination with agents known to prolong the QT interval including Class IA (e.g., quinidine or procainamide) or Class III (e.g., dofetilide, amiodarone, sotalol) antiarrhythmic agents, phenothiazines, tricyclic… (Foscarnet label, Drug interactions)

Avoid co-administration of CONTEPO with drugs known to prolong the QT interval. (Fosfomycin label, Drug interactions)

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

Although the clinical significance of this interaction is unknown, grapefruit juice should be avoided. (Quinidine label, Drug interactions)

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

Avoid the use of hydrocodone bitartrate and homatropine methylbromide while taking a CYP3A4 or CYP2D6 inhibitor. (Hydrocodone and homatropine label, Drug interactions)

Therefore, PLAQUENIL is not recommended in patients taking other drugs that have the potential to prolong the QT interval. (Hydroxychloroquine label, Warnings and precautions)

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

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Avoid the use of FANAPT in combination with any other drugs that prolong the QT interval [see Warnings and Precautions (5.3) ] . (Iloperidone label, Drug interactions)

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

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

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

Cardiac Dysrhythmias Life-threatening cardiac dysrhythmias and/or sudden death have occurred in patients using drugs such as, pimozide, methadone, or quinidine concomitantly with oral itraconazole and/or other CYP3A4 inhibitors. (Itraconazole label, Warnings and precautions)

Bradycardia may increase the risk of QT prolongation which may lead to severe ventricular arrhythmias, including torsade de pointes, especially in patients with risk factors such as use of QTc prolonging drugs [see Adverse Reactions ( 6.2 )] . (Ivabradine label, Warnings and precautions)

QT Prolongation and Drug Interactions Leading to QT Prolongation Coadministration of the following drugs with ketoconazole is contraindicated: dofetilide, quinidine, pimozide, lurasidone, cisapride, methadone, disopyramide, dronedarone, ranolazine. (Ketoconazole label, Boxed warning)

Since it cannot be excluded that Lanreotide Injection may have this effect, avoid other drugs mainly metabolized by CYP3A4 and which have a low therapeutic index (e.g., quinidine, terfenadine). (Lanreotide label, Drug interactions)

These conditions include patients with hypokalemia or hypomagnesemia, with congenital long QT syndrome, patients taking antiarrhythmic medicines or other medicinal products with known risk for QT prolongation/ Torsades de Pointes, and cumulative high-dose anthracycline therapy. (Lapatinib label, Warnings and precautions)

Avoid use in patients with known prolongation, those with hypokalemia, and with other drugs that prolong the QT interval ( 5.11 , 8.5 ) (Levofloxacin label, Warnings and precautions)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

If concomitant use of VYVANSE with other serotonergic drugs or CYP2D6 inhibitors is clinically warranted, initiate VYVANSE with lower doses, monitor patients for the emergence of serotonin syndrome during drug initiation or titration, and inform patients of the increased risk for serotonin syndrome. (Lisdexamfetamine label, Warnings and precautions)

Alpha 1- Adrenoreceptor Antagonist: alfuzosin Antianginal: ranolazine Antiarrhythmic: dronedarone Anti-gout: colchicine Antipsychotics: lurasidone, pimozide Ergot Derivatives: dihydroergotamine, ergotamine, methylergonovine GI Motility Agent: cisapride Hepatitis C direct acting antiviral: elbasvir/grazoprevir HMG-CoA Reductase Inhibitors: lovastatin, simvastatin… (Lopinavir and ritonavir label, Contraindications)

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

CONTRAINDICATIONS Use of mefloquine hydrochloride tablets is contraindicated in patients with a known hypersensitivity to mefloquine or related compounds (e.g., quinine and quinidine) or to any of the excipients contained in the formulation. (Mefloquine label, Contraindications)

Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The concomitant use of METHADOSE with all cytochrome P450 3A4, 2B6, 2C19, 2C9 or 2D6 inhibitors may result in an increase in methadone plasma concentrations, which could cause potentially fatal respiratory depression. (Methadone label, Boxed warning)

If serotonin syndrome occurs, discontinue methamphetamine hydrochloride tablets, USP and the CYP2D6 inhibitor [see Warnings and Precautions 5.8]. (Methamphetamine label, Drug interactions)

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

CYP2D6 Inhibitors Monitor patients closely when the combination use of CYP2D6 inhibitor and metoprolol cannot be avoided. (Metoprolol label, Drug interactions)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

…metabolized by CYP3A such as simvastatin, lovastatin, and CYP3A substrates with narrow therapeutic ranges, such as cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus, due to an increased risk of adverse events. [See Drug Interactions ( 7.1 ) and Clinical Pharmacology ( 12.3 )] Patients receiving systemic corticosteroids… (Mifepristone label, Contraindications)

Examples diazepam, alprazolam, alcohol Drugs that Prolong QTc Interval Clinical Impact The concomitant use of other drugs which prolong the QTc interval with REMERON/REMERONSolTab, increase the risk of QT prolongation and/or ventricular arrhythmias (e.g., Torsades de Pointes). (Mirtazapine label, Drug interactions)

Therefore, moxifloxacin should be avoided with Class IA and Class III antiarrhythmics [see Warnings and Precautions ( 5.6 ), Nonclinical Toxicology ( 13.2 ), and Patient Counseling Information ( 17 )]. (Moxifloxacin label, Drug interactions)

…concentrations are associated with serious and/or life-threatening reactions [see Drug Interactions (7.3) ] : • Alpha 1-adrenoreceptor antagonist: alfuzosin • Antianginal: ranolazine • Antiarrhythmic: amiodarone, dronedarone, flecainide, propafenone, quinidine • Anti-gout: colchicine (in patients with renal and/or hepatic impairment [see Table 2 , Drug Interactions… (Nirmatrelvir and ritonavir label, Contraindications)

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

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

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

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

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

Avoid coadministration of oxaliplatin injection with medicinal products with a known potential to prolong the QT interval. (Oxaliplatin label, Drug interactions)

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

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

Avoid concomitant use of VOTRIENT with strong inhibitors of P-gp or BCRP. (Pazopanib label, Drug interactions)

Drugs that Prolong the QT Interval : Avoid concomitant use. (Phenobarbital label, Drug interactions)

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

Because pimozide prolongs the QT interval of the electrocardiogram it is contraindicated in patients with congenital long QT syndrome, patients with a history of cardiac arrhythmias, patients taking other drugs which prolong the QT interval of the electrocardiogram or patients with known hypokalemia or hypomagnesemia (see also PRECAUTIONS - DRUG INTERACTIONS ). (Pimozide label, Contraindications)

The use of WAKIX should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval [see Drug Interactions ( 7.1 )]. (Pitolisant label, Warnings and precautions)

Class Ia (e.g., quinidine, procainamide) and Class III (e.g., amiodarone, sotalol) anti-arrhythmic drugs have been associated with cases of Torsades de Pointes in patients with bradycardia. (Ponesimod label, Drug interactions)

CYP3A4 substrates (pimozide, quinidine): can result in QTc interval prolongation and cases of torsades de pointes (TdP) ( 4.3 , 5.2 , 7.2 ) (Posaconazole label, Contraindications)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

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

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

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

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

CONTRAINDICATIONS Quinidine is contraindicated in patients who are known to be allergic to it, or who have a history of immune thrombocytopenia or have developed thrombocytopenic purpura during prior therapy with quinidine or quinine (see WARNINGS ). (Quinidine label, Contraindications)

• Potent Inhibitors of P-gp: Avoid another dose of NURTEC ODT within 48 hours when administered with a potent P-gp inhibitor. (Rimegepant label, Drug interactions)

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)

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

Avoid the concomitant use of drugs known to prolong the QTc interval. (Sertraline label, Drug interactions)

• Avoid concomitant use with strong CYP3A4/P-gp inducers or strong CYP3A4/P-gp inhibitors that decrease or increase sirolimus concentrations ( 7.4 , 12.3 ). (Sirolimus label, Drug interactions)

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

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Effect of Other Drugs on TALZENNA Effect of P-gp Inhibitors Breast Cancer Avoid coadministration of TALZENNA with the following P-gp inhibitors: itraconazole, amiodarone, carvedilol, clarithromycin, itraconazole, and verapamil. (Talazoparib label, Drug interactions)

Certain conditions may increase the risk for torsade de pointes or sudden death such as (1) bradycardia; (2) hypokalemia or hypomagnesemia; (3) concomitant use of other drugs that prolong the QTc interval; and (4) presence of congenital prolongation of the QT interval [see Warnings and Precautions ( 5.8 ), Clinical Pharmacology (12.2) ]. (Tetrabenazine label, Drug interactions)

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

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

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

Avoid concomitant use HYCAMTIN capsules with P-gp inhibitors or BCRP inhibitors. (Topotecan label, Drug interactions)

The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with tramadol are complex. (Tramadol label, Boxed warning)

Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with tramadol are complex. (Tramadol and acetaminophen 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)

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

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

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

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

QT Prolongation : Patients with congenital QT syndrome or taking class IA or III antiarrhythmics should avoid using vardenafil hydrochloride tablets. (Vardenafil label, Warnings and precautions)

Avoid concomitant use of VEPPANU with strong CYP3A inhibitors or drugs known to prolong the QTc interval. (Vepdegestrant label, Warnings and precautions)

Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ). (Quinidine label, Warnings)

Therefore, the concomitant use of P-gp inhibitors or inducers should be avoided. (Vincristine label, Drug interactions)

…life‑threatening reactions [see Drug Interactions (7) ]: • Eplerenone • Ergot alkaloids (e.g., ergotamine, dihydroergotamine) • Finerenone • Ivabradine • Lurasidone • Naloxegol • Pimozide • Quinidine • Rifabutin [see Clinical Pharmacology (12.3) ] • Sirolimus [see Clinical Pharmacology (12.3) ] • Tolvaptan • Venetoclax: Coadministration at initiation and during the ramp-up… (Voriconazole label, Contraindications)

Therefore, ziprasidone should not be given with: • dofetilide, sotalol, quinidine, other Class Ia and III anti-arrhythmics, mesoridazine, thioridazine, chlorpromazine, droperidol, pimozide, sparfloxacin, gatifloxacin, moxifloxacin, halofantrine, mefloquine, pentamidine, arsenic trioxide, levomethadyl acetate, dolasetron mesylate, probucol or tacrolimus. (Ziprasidone label, Contraindications)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

P-glycoprotein (P-gp) Inhibitors : Co-administration of P-gp inhibitors can increase afatinib exposure. (Afatinib label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

MAO inhibitors, tricyclic antidepressants and drugs that prolong the QTc interval may potentiate effect on the cardiovascular system. (Arformoterol label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

CYP2D6 inhibitors and CYP3A4 Inhibitors : See full prescribing information for ABILIFY MAINTENA dosage modifications when used concomitantly with CYP2D6 inhibitors and/or CYP3A4 inhibitors for greater than 14 days ( 7.1 ) (Aripiprazole label, Drug interactions)

Amiodarone is an antiarrhythmic agent with negative chronotropic properties that may be additive to those seen with beta-blockers. (Atenolol label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Strong CYP2D6 Inhibitors Prevention or Management With concomitant use of atomoxetine oral solution and a strong CYP2D6 inhibitor 1 , increase the titration interval [see Dosage and Administration (2.5) and Clinical Pharmacology (12.3) ] . (Atomoxetine label, Drug interactions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Amiodarone is an antiarrhythmic agent with negative chronotropic properties that may be additive to those seen with beta blockers. (Betaxolol label, Drug interactions)

Altered pharmacodynamics of other drugs: Quinidine's anticholinergic, vasodilating, and negative inotropic actions may be additive to those of other drugs with these effects, and antagonistic to those of drugs with cholinergic, vasoconstricting, and positive inotropic effects. (Quinidine label, Drug interactions)

Table 4 Drug Interactions with BIXLENVO Concomitant Drug Class: Drug Name Effect on Concentration ↑ = Increase, ↓ = Decrease Clinical Comment Antiarrhythmics: digoxin dofetilide ↑ digoxin ↑ dofetilide Use digoxin with caution and monitor digoxin therapeutic concentration. (Bictegravir, emtricitabine, and tenofovir alafenamide label, Drug interactions)

Drugs that Prolong the QT interval QT prolongation has been reported with metronidazole, a component of bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride, particularly when administered with drugs with the potential for prolonging the QT interval. (Bismuth subcitrate, metronidazole, and tetracycline label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

Strong CYP2D6 REXULTI may be administered without dosage adjustment in patients with MDD when administered with strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine). or CYP3A4 inhibitors Administer half of recommended dosage. (Brexpiprazole label, Drug interactions)

CYP2D6 inhibitors may potentiate systemic beta-blockade. (Brimonidine and timolol label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

The risk of combining buprenorphine with other QT-prolonging agents is not known. (Buprenorphine label, Warnings and precautions)

The risk of combining buprenorphine with other QT-prolonging agents is not known. (Buprenorphine and naloxone label, Warnings and precautions)

Drugs Metabolized by CYP2D6: Bupropion inhibits CYP2D6 and can increase concentrations of: antidepressants (e.g., venlafaxine, nortriptyline, imipramine, desipramine, paroxetine, fluoxetine, sertraline), antipsychotics (e.g., haloperidol, risperidone, thioridazine), beta-blockers (e.g., metoprolol), and Type 1C antiarrhythmics (e.g., propafenone, flecainide). (Bupropion label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

CYP2D6 Inhibitors and Poor Metabolizers Interactions of carvedilol with potent inhibitors of CYP2D6 isoenzyme (such as quinidine, fluoxetine, paroxetine, and propafenone) have not been studied, but these drugs would be expected to increase blood levels of the R(+) enantiomer of carvedilol [see Clinical Pharmacology (12.3) ]. (Carvedilol label, Drug interactions)

Altered pharmacodynamics of other drugs: Quinidine's anticholinergic, vasodilating, and negative inotropic actions may be additive to those of other drugs with these effects, and antagonistic to those of drugs with cholinergic, vasoconstricting, and positive inotropic effects. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

By pharmacokinetic mechanisms that are not well understood, quinidine levels are increased by coadministration of amiodarone or cimetidine . (Quinidine label, Drug interactions)

QT Interval Prolongation and V entricular A rr h ythmia Decreases in serum calcium can also prolong the QT interval, potentially resulting in ventricular arrhythmia. (Cinacalcet label, Warnings and precautions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

Avoid use of Citalopram Capsules in patients with congenital long QT syndrome, bradycardia, hypokalemia or hypomagnesemia, recent acute myocardial infarction, or uncompensated heart failure and patients taking other drugs that prolong the QTc interval. (Citalopram label, Warnings and precautions)

If the antiretroviral regimen must be withheld for a prolonged period, consideration should be given to initiating a revised regimen that does not include a CYP3A or P-gp inhibitor. (Darunavir label, Drug interactions)

Other antiarrhythmics e.g. amiodarone, disopyramide, flecainide, lidocaine (systemic), mexiletine, propafenone, quinidine ↑ antiarrhythmics Clinical monitoring is recommended upon co-administration with antiarrhythmics. digoxin ↑ digoxin When co-administering with digoxin, titrate the digoxin dose and monitor digoxin concentrations. (Darunavir and cobicistat label, Drug interactions)

QT Prolongation PHYRAGO may increase the risk of prolongation of QTc in patients including those with hypokalemia or hypomagnesemia, patients with congenital long QT syndrome, patients taking antiarrhythmic medicines or other medicinal products that lead to QT prolongation, and cumulative high-dose anthracycline therapy [see Adverse Reactions ( 6.1 )] . (Dasatinib label, Warnings and precautions)

…ergotamine, everolimus, felodipine, fentanyl, hormonal contraceptive agents, indinavir, fluticasone, lopinavir, lovastatin, lurasidone, maraviroc, midazolam, nisoldipine, pimozide, quetiapine, quinidine, saquinavir, sildenafil, simvastatin, sirolimus, tacrolimus, tolvaptan, tipranavir, triazolam, ticagrelor, and vardenafil) [see Clinical Pharmacology (12.3)] . (Deferasirox label, Drug interactions)

Carefully monitor cardiac rhythm when administering SUPRANE to susceptible patients (e.g., patients with congenital Long QT Syndrome or patients taking drugs that can prolong the QT interval). (Desflurane label, Warnings and precautions)

Concomitant use of strong CYP2D6 inhibitors: Maximum recommended dose of AUSTEDO XR or AUSTEDO is 36 mg per day ( 2.3 , 7.1 ) (Deutetrabenazine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

…development of prolonged QT syndrome, such as: 1) clinically significant bradycardia (less than 50 bpm), 2) any clinically significant cardiac disease, 3) treatment with Class I and Class III antiarrhythmics, 4) treatment with monoamine oxidase inhibitors (MAOI's), 5) concomitant treatment with other drug products known to prolong the QT interval (see PRECAUTIONS,… (Droperidol label, Warnings)

Use caution in combination with moderate CYP3A4 inhibitors (e.g., erythromycin) or strong (e.g., paroxetine) or moderate CYP2D6 inhibitors, a combination of both CYP3A4 and CYP2D6 inhibitors, or known poor metabolizers of CYP2D6. (Dutasteride and tamsulosin label, Warnings and precautions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

QT Prolonging Drugs There is limited information available on the potential for a pharmacodynamic interaction between efavirenz and drugs that prolong the QTc interval. (Efavirenz label, Drug interactions)

QT Prolonging Drugs There is limited information available on the potential for a pharmacodynamic interaction between EFV and drugs that prolong the QTc interval. (Efavirenz, lamivudine, and tenofovir label, Drug interactions)

Antiarrhythmics: e.g., amiodarone bepridil digoxin Indicates that a drug-drug interaction trial was conducted. disopyramide flecainide systemic lidocaine mexiletine propafenone quinidine ↑ antiarrhythmics ↑ digoxin Caution is warranted and therapeutic concentration monitoring, if available, is recommended for antiarrhythmics when coadministered with GENVOYA. (Elvitegravir, cobicistat, emtricitabine, and tenofovir label, Drug interactions)

Coadministration of DESCOVY with other drugs that inhibit P-gp and BCRP may increase the absorption and plasma concentration of TAF. (Emtricitabine and tenofovir label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

QT Prolongation: Monitor for prolonged QT intervals in patients with congestive heart failure, bradyarrhythmias, drugs known to prolong the QT interval, and electrolyte abnormalities. (Eribulin label, Warnings and precautions)

Erythromycin should be avoided in patients with known prolongation of the QT interval, patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia, clinically significant bradycardia, and in patients receiving Class IA (quinidine, procainamide) or Class III (dofetilide, amiodarone, sotalol) antiarrhythmic agents. (Erythromycin label, Warnings)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Other agents Antiarrhythmics : digoxin ↔ etravirine ↑ digoxin For patients who are initiating a combination of Etravirine and digoxin, the lowest dose of digoxin should initially be prescribed. (Etravirine label, Drug interactions)

…as: 1) clinically significant bradycardia (less than 50 bpm), 2) any clinically significant cardiac disease, including baseline prolonged QT interval, 3) treatment with Class 1 and Class III antiarrhythmics, 4) treatment with monoamine oxidase inhibitors (MAOI's), 5) concomitant treatment with other drug products known to prolong the QT interval and 6) electrolyte… (Fentanyl label, Warnings and precautions)

Concentrations of fidaxomicin and OP-1118 may also be decreased at the site of action (i.e., gastrointestinal tract) via P-gp inhibition; however, concomitant P-gp inhibitor use had no attributable effect on safety or treatment outcome of fidaxomicin-treated adult patients in controlled clinical trials. (Fidaxomicin label, Drug interactions)

Use with caution in combination with other drugs that prolong the QT interval ( 4.2 , 5.11 , 7.7 , 7.8 ) 7.1 Monoamine Oxidase Inhibitors (MAOI) [See Dosage and Administration ( 2.9 , 2.10 ), Contraindications ( 4.1 ), and Warnings and Precautions ( 5.2 )] . (Fluoxetine label, Drug interactions)

Caution is indicated in patients known to have reduced levels of CYP2D6 activity and those receiving concomitant drugs known to inhibit this cytochrome P450 isoenzyme (e.g., quinidine). (Fluvoxamine label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

…Antidepressants, QTc Prolonging Drugs Formoterol, as with other beta 2 -agonists, should be administered with extreme caution to patients being treated with monoamine oxidase inhibitors, tricyclic antidepressants, or drugs known to prolong the QTc interval because the effect of adrenergic agonists on the cardiovascular system may be potentiated by these agents. (Formoterol label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Anticoagulants Apixaban, dabigatran, edoxaban, rivaroxaban Antiepileptic drugs The effect of phenytoin on phenobarbital, valproic acid and sodium valproate serum levels… (Fosphenytoin label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

CYP3A4 Substrates with narrow therapeutic index (e.g., alfentanil, quinidine, cyclosporine) : Glycerol phenylbutyrate may decrease exposure; monitor for decreased efficacy of the narrow therapeutic index drug ( 7.3 ) (Glycerol phenylbutyrate label, Drug interactions)

Effect on QT/QTc Interval: Androgen deprivation therapy may prolong the QT interval. (Goserelin label, Warnings and precautions)

Serum levels of haloperidol are increased when quinidine is coadministered. (Quinidine label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

This observation should be considered in making clinical decisions regarding patient monitoring when prescribing HYSINGLA ER in patients with congestive heart failure, bradyarrhythmias, electrolyte abnormalities, or who are taking medications that are known to prolong the QTc interval. (Hydrocodone label, Warnings and precautions)

These effects could be more pronounced with concomitant use of hydrocodone bitartrate and acetaminophen tablets and both CYP3A4 and CYP2D6 inhibitors, particularly when an inhibitor is added after a stable dose of hydrocodone bitartrate and acetaminophen tablets is achieved [see WARNINGS ]. (Hydrocodone and acetaminophen label, Drug interactions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Monitor QT interval when administering FORANE to susceptible patients (e.g., patients with congenital Long QT Syndrome or patients taking drugs that can prolong the QT interval). (Isoflurane label, Warnings and precautions)

Antiarrhythmics: amiodarone Effect on amiodarone, ledipasvir, and sofosbuvir concentrations unknown Coadministration of amiodarone with ledipasvir and sofosbuvir may result in serious symptomatic bradycardia. (Ledipasvir and sofosbuvir label, Drug interactions)

Clinical Comment Antiarrhythmics: digoxin ↑ digoxin Use with caution and monitor digoxin therapeutic concentration. (Lenacapavir label, Drug interactions)

Effect on QT/QTc Interval: Androgen deprivation therapy may prolong the QT interval. (Leuprolide label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Risk of QT Prolongation : Lofexidine tablets prolong the QT interval. (Lofexidine label, Warnings and precautions)

…combination with others drugs or herbal products that are known to prolong the QT interval, including Class 1A (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmics, antipsychotics (e.g., chlorpromazine, haloperidol, thioridazine, ziprasidone), antibiotics (e.g., moxifloxacin), or any other drug known to prolong the QT interval… (Loperamide label, Warnings)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Examples quinidine, bupropion, fluoxetine, and paroxetine Monoamine Oxidase Inhibitors Clinical Impact Increased risk of hypertension [see Warnings and Precautions ( 5.5 )] . (Metoclopramide label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that Prolong the QT Interval QT prolongation has been reported, particularly when metronidazole was administered with drugs with the potential for prolonging the QT interval. (Metronidazole label, Drug interactions)

P-Glycoprotein (P-gp) Inhibitors Clinical Impact: The concomitant use of P-gp inhibitors can increase the exposure to morphine by two-fold and can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death. (Morphine label, Drug interactions)

P-glycoprotein (P-gp) Inhibitors (e.g., amiodarone, captopril, cyclosporine, quercetin, quinidine, verapamil) Clinical Impact Increase in plasma naldemedine concentrations [see Clinical Pharmacology (12.3) ] Intervention Monitor for potential naldemedine-related adverse reactions [see Adverse Reactions (6.1) ] . (Naldemedine label, Drug interactions)

•Weak CYP3A4 inhibitors (e.g., quinidine, cimetidine) •Clinically significant increases in naloxegol concentrations are not expected. (Naloxegol label, Drug interactions)

Drugs Metabolized by CYP2D6: Bupropion inhibits CYP2D6 and can increase concentrations of antidepressants, (e.g., selective serotonin reuptake inhibitors and many tricyclics), antipsychotics (e.g., haloperidol, risperidone and thioridazine), beta-blockers (e.g., metoprolol) and Type 1C antiarrhythmics (e.g., propafenone and flecainide). (Naltrexone and bupropion label, Drug interactions)

Use with CYP2D6 Inhibitors Nebivolol exposure increases with inhibition of CYP2D6 [see Drug Interactions ( 7 ) ] . (Nebivolol label, Warnings and precautions)

…nefazodone and its major metabolites are not altered in these “poor metabolizers.” Plasma concentrations of one minor metabolite (mCPP) are increased in this population; the adjustment of nefazodone dosage is not required when administered to “poor metabolizers.” Nefazodone and its metabolites have been shown in vitro to be extremely weak inhibitors of CYP2D6. (Nefazodone label, Drug interactions)

Antiarrhythmics: Amiodarone, disopyramide, lidocaine Plasma concentrations may be decreased. (Nevirapine label, Drug interactions)

Very rarely, and again by mechanisms not understood, quinidine levels are decreased by coadministration of nifedipine . (Quinidine label, Drug interactions)

Quinidine at 648 mg bid decreased the bioavailability (AUC) of nisoldipine by 26%, but not the peak concentration. (Nisoldipine label, Drug interactions)

Drugs Metabolized by CYP 450 Enzymes: concomitant use with other drugs mainly metabolized by CYP3A4 that have a narrow therapeutic index (e.g., quinidine) should be used with caution and increased monitoring may be required (‎ 7 ). (Octreotide label, Drug interactions)

Ofloxacin should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia, and patients receiving Class IA (quinidine, procainamide), or Class III (amiodarone, sotalol) antiarrhythmic agents. (Ofloxacin label, Precautions)

Examples: Paroxetine, fluoxetine, quinidine, bupropion Moderate to Strong Inhibitors of CYP3A4 Clinical Impact: The concomitant administration of moderate to strong CYP3A4 inhibitors can increase the plasma concentration of oliceridine, resulting in increased or prolonged opioid adverse reactions. (Oliceridine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

The dose of the sensitive CYP3A substrate with a narrow therapeutic index (e.g., alfentanil, cyclosporine, dihydroergotamine, ergotamine, everolimus, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus) may need to be reduced, as IBRANCE may increase its exposure [see Clinical Pharmacology (12.3) ] . (Palbociclib label, Drug interactions)

…combination with other drugs that are known to prolong QTc including Class 1A (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmic medications, antipsychotic medications (e.g., chlorpromazine, thioridazine), antibiotics (e.g., gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval. (Paliperidone label, Warnings and precautions)

Drugs that Prolong QT: Use with caution in patients who are at significant risk of developing QTc prolongation. (Pasireotide label, Drug interactions)

…decreased PT/INR responses have been reported when phenytoin is coadministered with warfarin Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Anticoagulants Apixaban, dabigatran, edoxaban, rivaroxaban Antiepileptic drugs… (Phenytoin label, Drug interactions)

Altered pharmacodynamics of other drugs: Quinidine's anticholinergic, vasodilating, and negative inotropic actions may be additive to those of other drugs with these effects, and antagonistic to those of drugs with cholinergic, vasoconstricting, and positive inotropic effects. (Quinidine label, Drug interactions)

The use of NUPLAZID should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong QT interval including Class 1A antiarrhythmics (e.g., quinidine, procainamide) or Class 3 antiarrhythmics (e.g., amiodarone, sotalol), certain antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine), and certain… (Pimavanserin label, Warnings and precautions)

QT Interval Prolonging Drugs The pharmacodynamic interaction potential to prolong the QT interval of the electrocardiogram between Primaquine phosphate Tablets and other drugs that effect cardiac conduction is unknown. (Primaquine label, Drug interactions)

Impact of Other Drugs on Propranolol CYP2D6, CYP1A2 and CYP2C19 Inhibitors: CYP2D6 inhibitors (e.g. bupropion, fluoxetine, paroxetine, quinidine), CYP1A2 inhibitors (e.g., ciprofloxacin, enoxamine, fluvoxamine) and CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) increase exposure to propranolol when co-administered with INNOPRAN XL. (Propranolol label, Drug interactions)

Altered pharmacodynamics of other drugs: Quinidine's anticholinergic, vasodilating, and negative inotropic actions may be additive to those of other drugs with these effects, and antagonistic to those of drugs with cholinergic, vasoconstricting, and positive inotropic effects. (Quinidine label, Drug interactions)

…Class 1A antiarrythmics (e.g., quinidine, procainamide) or Class III antiarrythmics (e.g., amiodarone, sotalol), antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine), antibiotics (e.g., gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval (e.g., pentamidine, levomethadyl acetate, methadone). (Quetiapine label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

…non-hormonal methods of birth control during rifampin therapy Estrogens Decrease exposure Progestins Anticonvulsants Phenytoin Administered with rifampin 450 mg daily Decrease exposure Antiarrhythmics Disopyramide Decrease exposure Mexiletine Decrease exposure Quinidine Decrease exposure Propafenone Decrease AUC by 50%-67% Tocainide Decrease exposure Antiestrogens… (Rifampin label, Drug interactions)

Table 4: Drug Interactions with PRIFTIN: Dosage Adjustment May be Necessary Drug Class Examples of Drugs Within Class Antiarrhythmics Disopyramide, mexiletine, quinidine, tocainide Antibiotics Chloramphenicol, clarithromycin, dapsone, doxycycline; Fluoroquinolones (such as ciprofloxacin) Oral Anticoagulants Warfarin Anticonvulsants Phenytoin Antimalarials Quinine… (Rifapentine label, Drug interactions)

• Concomitant P-glycoprotein (P-gp) inhibitors (e.g., cyclosporine): Caution should be exercised when concomitant use of XIFAXAN and a P-glycoprotein inhibitor is needed. (Rifaximin label, Warnings and precautions)

In healthy subjects, 75 mg once daily and 300 mg once daily (3 times and 12 times the dose in EDURANT) have been shown to prolong the QTc interval of the electrocardiogram. (Rilpivirine label, Warnings and precautions)

Fluoxetine and Paroxetine Fluoxetine (20 mg once daily) and paroxetine (20 mg once daily), CYP 2D6 inhibitors, have been shown to increase the plasma concentration of risperidone 2.5–2.8 fold and 3–9 fold respectively. (Risperidone label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

…anesthetics or agents structurally related to amide- type local anesthetics, since the toxic effects of these drugs are additive. [See Drug Interactions 7.0 ] Patients treated with class III antiarrhythmic drugs (e.g., amiodarone) should be under close surveillance and ECG monitoring considered, since cardiac effects may be additive. [See Drug Interactions 7.0… (Ropivacaine label, Warnings and precautions)

Caution should be exercised when administering sevoflurane to susceptible patients (e.g., patients with congenital Long QT Syndrome or patients taking drugs that can prolong the QT interval). (Sevoflurane label, Warnings)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Antiarrhythmics: amiodarone Effect on amiodarone, sofosbuvir, velpatasvir, and voxilaprevir concentrations unknown Coadministration of amiodarone with VOSEVI may result in serious symptomatic bradycardia. (Sofosbuvir and velpatasvir label, Drug interactions)

Monitor electrolytes and electrocardiograms in patients with congestive heart failure, bradyarrhythmias, drugs known to prolong the QT interval, including Class Ia and III antiarrhythmics. (Sorafenib label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

In addition, in vitro addition of quinidine to the serum of pregnant women reduces the activity of pseudo-cholinesterase, an enzyme that is essential to the metabolism of succinylcholine. (Quinidine label, Drug interactions)

Drug Interactions Some studies have shown that simultaneous sucralfate administration in healthy volunteers reduced the extent of absorption (bioavailability) of single doses of the following: cimetidine, digoxin, fluoroquinolone antibiotics, ketoconazole, l-thyroxine, phenytoin, quinidine, ranitidine, tetracycline, and theophylline. (Sucralfate label, Drug interactions)

Monitor patients who are at higher risk of developing QT interval prolongation, including patients with a history of QT interval prolongation, patients who are taking antiarrhythmics, or patients with relevant pre-existing cardiac disease, bradycardia, or electrolyte disturbances. (Sunitinib label, Warnings and precautions)

…electrocardiograms and monitoring electrolytes (magnesium, potassium, calcium) periodically during treatment in patients with congestive heart failure, bradyarrhythmias, those taking certain antiarrhythmic medications or other products that lead to QT prolongation, and those with electrolyte disturbances (e.g., hypokalemia, hypocalcemia, or hypomagnesemia). (Tacrolimus label, Warnings and precautions)

Use with caution in combination with moderate inhibitors of CYP3A4, with strong or moderate inhibitors of CYP2D6, in patients known to be CYP2D6 poor metabolizers, or in combination with other cytochrome P450 inhibitors. (Tamsulosin label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Potentiated systemic beta-blockade (e.g., decreased heart rate) has been reported during combined treatment with quinidine and timolol. (Timolol label, Drug interactions)

Agents generally accepted to prolong QT interval include Class 1A (e.g., quinidine, procainamide, disopyramide) and Class III (e.g., amiodarone, sotalol, ibutilide, dofetilide) antiarrhythmics; certain antipsychotics (e.g., thioridazine, haloperidol); certain antidepressants (e.g., venlafaxine, amitriptyline); certain antibiotics (e.g., erythromycin, clarithromycin,… (Toremifene label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

…prolongation or in combination with other drugs that are inhibitors of CYP3A4 (e.g., itraconazole, clarithromycin, voriconazole), or known to prolong QT interval including Class 1A antiarrhythmics (e.g., quinidine, procainamide) or Class 3 antiarrhythmics (e.g., amiodarone, sotalol), certain antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine),… (Trazodone label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Effect on QT/QTc Interval: Androgen deprivation therapy may prolong the QT interval. (Triptorelin label, Warnings and precautions)

Use of BCRP and/or P-gp only inhibitors (e.g., quinidine, carvedilol, eltrombopag, curcumin) may increase the exposure of ubrogepant [ s ee Clinical Pharmacology ( 12.3 ) ] . (Ubrogepant label, Drug interactions)

For patients who are CYP2D6 poor metabolizers or are taking a strong CYP2D6 inhibitor, dose reduction may be necessary. (Valbenazine label, Warnings and precautions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

Quinidine potentiates the actions of depolarizing (succinylcholine, decamethonium) and non-depolarizing ( d -tubocurarine, pancuronium) neuromuscular blocking agents . (Quinidine label, Drug interactions)

Therefore, the potential exists for a drug interaction between drugs that inhibit CYP2D6-mediated metabolism of venlafaxine, reducing the metabolism of venlafaxine to ODV, resulting in increased plasma concentrations of venlafaxine and decreased concentrations of the active metabolite. (Venlafaxine label, Drug interactions)

CYP2D6 Substrates Clinical Impact Viloxazine is a weak inhibitor of CYP2D6, and increases the exposure of CYP2D6 substrates when coadministered [see Clinical Pharmacology (12.3) ] . (Viloxazine label, Drug interactions)

Examples bupropion, fluoxetine, paroxetine, quinidine Strong CYP Inducers Clinical Impact Concomitant use of TRINTELLIX with a strong CYP inducer decreases plasma concentrations of vortioxetine. (Vortioxetine label, Drug interactions)

By a mechanism that is not understood, quinidine potentiates the anticoagulatory action of warfarin , and the anticoagulant dosage may need to be reduced. (Quinidine label, Drug interactions)

Drugs that alkalinize the urine ( carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics ) reduce renal elimination of quinidine. (Quinidine label, Drug interactions)

The effects (if any) of coadministration of other β-blockers on quinidine pharmacokinetics have not been adequately studied. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Pediatric use In antimalarial trials, quinidine was as safe and effective in pediatric patients as in adults. (Quinidine label, Precautions)

Pediatric use In antimalarial trials, quinidine was as safe and effective in pediatric patients as in adults. (Quinidine label, Precautions)

The effects (if any) of coadministration of other β-blockers on quinidine pharmacokinetics have not been adequately studied. (Quinidine label, Drug interactions)

Conversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine . (Quinidine label, Drug interactions)

Conversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine . (Quinidine label, Drug interactions)

Conversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine . (Quinidine label, Drug interactions)

CYP2D6 substrates Clinical Impact: In vitro studies indicate that celecoxib, although not a substrate, is an inhibitor of CYP2D6. (Celecoxib label, Drug interactions)

Pediatric use In antimalarial trials, quinidine was as safe and effective in pediatric patients as in adults. (Quinidine label, Precautions)

The selective serotonin reuptake inhibitors sertraline (weak CYP3A4 inducer) and fluoxetine (CYP2D6 inhibitor), and the anti-epileptic drug felbamate (CYP2C19 inhibitor and CYP3A4 inducer) do not affect the pharmacokinetics of clonazepam. (Clonazepam label, Drug interactions)

Dapagliflozin or dapagliflozin 3-O-glucuronide did not meaningfully inhibit P-gp, OCT2, OAT1, or OAT3 active transporters. (Dapagliflozin label, Drug interactions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)

Examples: α-adrenergic antagonists, β-adrenergic receptor antagonists, reserpine, quinidine, mephentermine Other Drug Interactions G u anethidine C linical Impact: Ephedrine may inhibit the neuron blockage produced by guanethidine, resulting in loss of antihypertensive effectiveness. (Ephedrine label, Drug interactions)

Conversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine . (Quinidine label, Drug interactions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)

Conversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine . (Quinidine label, Drug interactions)

In the case of prodrugs whose actions are actually mediated by P450 IID6 -produced metabolites (for example, codeine and hydrocodone , whose analgesic and antitussive effects appear to be mediated by morphine and hydromorphone, respectively), it may not be possible to achieve the desired clinical benefits in poor metabolizers. (Quinidine label, Drug interactions)

In the case of prodrugs whose actions are actually mediated by P450 IID6 -produced metabolites (for example, codeine and hydrocodone , whose analgesic and antitussive effects appear to be mediated by morphine and hydromorphone, respectively), it may not be possible to achieve the desired clinical benefits in poor metabolizers. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

The effects (if any) of coadministration of other β-blockers on quinidine pharmacokinetics have not been adequately studied. (Quinidine label, Drug interactions)

Cardiac Rhythm and Conduction Abnormalities In vitro testing showed that lamotrigine exhibits Class IB antiarrhythmic activity at therapeutically relevant concentrations [see Clinical Pharmacology ( 12.2 )] . (Lamotrigine label, Warnings and precautions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)

P-glycoprotein Substrates Lomitapide is an inhibitor of P-glycoprotein (P-gp). (Lomitapide label, Drug interactions)

Effect of Other Drugs on the Metabolism of Donepezil Inhibitors of CYP3A4 (e.g., ketoconazole) and CYP2D6 (e.g., quinidine), inhibit donepezil metabolism in vitro . (Memantine and donepezil label, Drug interactions)

…for Drug Interaction: It appears possible, although there is no supporting experimental evidence, that the high renal clearance of desglymidodrine (a base) is due to active tubular secretion by the base-secreting system also responsible for the secretion of such drugs as metformin, cimetidine, ranitidine, procainamide, triamterene, flecainide, and quinidine. (Midodrine label, Precautions)

…untoward clinical manifestations have been observed in limited experience with patients in whom milrinone was used concurrently with the following drugs: digitalis glycosides; lidocaine, quinidine; hydralazine, prazosin; isosorbide dinitrate, nitroglycerin; chlorthalidone, furosemide, hydrochlorothiazide, spironolactone; captopril; heparin, warfarin, diazepam, insulin;… (Milrinone label, Drug interactions)

The effects (if any) of coadministration of other β-blockers on quinidine pharmacokinetics have not been adequately studied. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Conversely, the pharmacokinetics of quinidine are not significantly affected by caffeine, ciprofloxacin, digoxin, felodipine, omeprazole, or quinine . (Quinidine label, Drug interactions)

Pentoxifylline extended-release tablets have been used concurrently with antihypertensive drugs, beta blockers, digitalis, diuretics, and antiarrhythmics, without observed problems. (Pentoxifylline label, Drug interactions)

Drug Interactions Metabolism of a number of medications, including antipsychotics, antidepressants, β-blockers, and antiarrhythmics, occurs through the cytochrome P450 2D6 isoenzyme (debrisoquine hydroxylase). (Perphenazine label, Drug interactions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)

The effects (if any) of coadministration of other β-blockers on quinidine pharmacokinetics have not been adequately studied. (Quinidine label, Drug interactions)

…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 and anti-inflammatories–propoxyphene, aspirin, indomethacin, and phenylbutazone. (Prazosin label, Drug interactions)

Pediatric use In antimalarial trials, quinidine was as safe and effective in pediatric patients as in adults. (Quinidine label, Precautions)

Strong P-glycoprotein (P-gp) Inhibitors In vitro studies indicated that silodosin is a P‑gp substrate. (Silodosin label, Drug interactions)

Pediatric use In antimalarial trials, quinidine was as safe and effective in pediatric patients as in adults. (Quinidine label, Precautions)

Strong Inhibitors of CYP2D6 The impact on the efficacy of tamoxifen with co-administration of strong CYP2D6 inhibitors (e.g., paroxetine) is not well established. (Tamoxifen label, Drug interactions)

Interactions with other dihydropyridine calcium channel blockers have not been reported, but these agents (including felodipine, nicardipine, and nimodipine ) are all dependent upon P450 IIIA4 for metabolism, so similar interactions with quinidine should be anticipated. (Quinidine label, Drug interactions)

Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug classes: tricyclic antidepressants, selective serotonin reuptake inhibitors, beta-blockers, antiarrhythmics class 1C (e.g., flecainide and propafenone) and monoamine oxidase inhibitors Type B. (Terbinafine label, Drug interactions)

Moderate or Weak CYP1A2 Inhibitors Concomitant use of Zanaflex with moderate or weak CYP1A2 inhibitors (e.g., zileuton, antiarrhythmics [amiodarone, mexiletine, propafenone, and verapamil], cimetidine, famotidine, oral contraceptives, acyclovir, and ticlopidine) should be avoided. (Tizanidine label, Drug interactions)

Quinidine's pharmacokinetics are also unaffected by cigarette smoking. (Quinidine label, Drug interactions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)

Cytochrome P450 IID6 is an enzyme critical to the metabolism of many drugs, notably including mexiletine , some phenothiazines , and most polycyclic antidepressants . (Quinidine label, Drug interactions)