Diltiazem and Itraconazole interaction
Diltiazem and Itraconazole: 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 Itraconazole (Tolsura) label · effective 2025-04-23
Antiarrhythmics Disopyramide Dofetilide Dronedarone Quinidine Contraindicated during and 2 weeks after TOLSURA treatment.
Calcium Channel Blockers Felodipine Nisoldipine Contraindicated during and 2 weeks after TOLSURA treatment.
Diltiazem Other dihydropyridines Verapamil Monitor for adverse reactions.
Calcium channel blockers can have negative inotropic effects which may be additive to those of itraconazole.
Therefore, when co-administering itraconazole and calcium channel blockers, monitor carefully for signs and symptoms of CHF during treatment due to an increased risk of CHF.
From the Diltiazem (DILTIAZEM HYDROCHLORIDE in SODIUM CHLORIDE) label · effective 2025-04-15
Strong or moderate CYP 3A inhibitors a Examples b : Ketoconazole, itraconazole, cimetidine Patients currently receiving diltiazem therapy should be carefully monitored for a change in pharmacological effect when initiating and discontinuing therapy with strong or moderate inhibitors of CYP3A4.
Effect of other drugs on Diltiazem Cytochrome P450 3A4 Inhibitors/ Inducers Diltiazem is a substrate of the cytochrome P450 3A4 enzyme and inhibitors/inducers may change the pharmacological effect of diltiazem Monitor.
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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.