Carbamazepine and Diltiazem interaction
Carbamazepine and Diltiazem: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Diltiazem (DILTIAZEM HYDROCHLORIDE in SODIUM CHLORIDE) label · effective 2025-04-15
Coadministration of diltiazem with rifampin or any known CYP3A4 inducer should be avoided when possible, and alternative therapy considered [see Clinical Pharmacology (12.3)]. a Strong and moderate inhibitors increase the AUC of sensitive substrates of CYP3A4 by ≥ 5 and ≥ 2-fold, respectively b These examples are a guide and not considered a comprehensive list…
• CYP3A4 Inducers: Avoid concomitant use.
An adjustment in the diltiazem dose may be warranted CYP inducers Examples b : Rifampin, carbamazepine CYP3A inducers can lower the plasma levels of diltiazem.
Buspirone Carbamazepine Cyclosporine Quinidine Ranolazine Limit ranolazine to 500 mg twice daily.
From the Carbamazepine (EQUETRO) label · effective 2025-08-19
It may be necessary to reduce the EQUETRO dose if used concomitantly with inhibitors of CYP3A4 and/or epoxide hydrolase.
Cytochrome (CYP) 3A4 inhibitors, epoxide hydrolase inhibitors, CYP3A4 inducers, drugs metabolized by CYP1A2 or CYP3A4 (oral contraceptives, delavirdine, nefazodone), phenytoin, CNS depressants, lithium, chloroquine, mefloquine ( 7.1 , 7.2 , 7.3 )
The following drugs are CYP3A4 inhibitors: Acetazolamide, aprepitant, azole antifungals (e.g., ketoconazole, itraconazole, fluconazole, voriconazole ) , cimetidine, ciprofloxacin, clarithromycin, dalfopristin, danazol, dantrolene, delavirdine, diltiazem, erythromycin, fluoxetine, fluvoxamine, grapefruit juice, ibuprofen, isoniazid, loratadine, nefazodone, niacinamide,…
…alprazolam, aprepitant, buprenorphone, bupropion, buspirone, citalopram, clobazam, clonazepam, clozapine, cyclosporin, delavirdine, desipramine, diazepam, dicumarol, dihydropyridine calcium channel blockers (e.g., felodipine), doxycycline, ethosuximide, everolimus, felbamate, glucocorticoids, haloperidol, imatinib, itraconazole, lamotrigine, levothyroxine, lorazepam,…
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.