Nifedipine and Quinidine interaction
Nifedipine and Quinidine: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Nifedipine label · effective 2026-02-05
Co-administration of multiple doses of quinidine sulfate, 200 mg t.i.d., and nifedipine, 20 mg t.i.d., increased C max and AUC of nifedipine in healthy volunteers by factors of 2.30 and 1.37, respectively.
Monitoring of heart rate and adjustment of the nifedipine dose, if necessary, are recommended when quinidine is added to a treatment with nifedipine.
The exposure to quinidine was not importantly changed in the presence of nifedipine.
Cardiovascular Drugs Antiarrhythmics Quinidine: Quinidine is a substrate of CYP3A and has been shown to inhibit CYP3A in vitro .
From the Quinidine (Quinidine Gluconate) label · effective 2024-08-27
Very rarely, and again by mechanisms not understood, quinidine levels are decreased by coadministration of nifedipine .
Presumably because both drugs are metabolized by cytochrome P450 IIIA4 , coadministration of quinidine causes variable slowing of the metabolism of nifedipine .
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.
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.