Selected Calcium Channel Blockers/Rifamycins
This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.
Medical warning:
Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
When these two medicines are taken together, your body may not process your calcium channel blocker correctly.
What might happen:
The beneficial effects of your calcium channel blocker may decrease.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Your doctor may want to change the dose of your calcium channel blocker while you are taking rifampin and for a few weeks after you are done taking it.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this drug interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
References:
1.Isradipine US prescribing information. Cobalt Laboratories April, 2007.
2.Cardizem LA (diltiazem hcl extended release tablets) US prescribing information. BTA Pharmaceuticals, Inc. November, 2010.
3.Saima S, Furuie K, Yoshimoto H, Fukuda J, Hayashi T, Echizen H. The effects of rifampicin on the pharmacokinetics and pharmacodynamics of orally administered nilvadipine to healthy subjects. Br J Clin Pharmacol 2002 Feb;53(2):203-6.
4.Barbarash RA, Bauman JL, Fischer JH, Kondos GT, Batenhorst RL. Near-total reduction in verapamil bioavailability by rifampin. Electrocardiographic correlates. Chest 1988 Nov;94(5):954-9.
5.Fromm MF, Busse D, Kroemer HK, Eichelbaum M. Differential induction of prehepatic and hepatic metabolism of verapamil by rifampin. Hepatology 1996 Oct;24(4):796-801.
6.Yoshimoto H, Takahashi M, Saima S. Influence of rifampicin on antihypertensive effects of dihydropiridine calcium-channel blockers in four elderly patients. Nippon Ronen Igakkai Zasshi 1996 Sep;33(9):692-6.
7.Rahn KH, Mooy J, Bohm R, vd Vet A. Reduction of bioavailability of verapamil by rifampin. N Engl J Med 1985 Apr 4;312(14):920-1.
8.Barbarash RA. Verapamil-rifampin interaction. Drug Intell Clin Pharm 1985 Jul-Aug;19(7-8):559-60.
