| Drug Interactions:

Calcium Channel Blockers

Calcium and Vitamin D —Possible Decreased Action of Drug | Ginkgo Biloba —Possible Decreased Action of Drug | Naringen (a Citrus Bioflavonoid)—May Necessitate Reduction of Drug Dosage

Calcium channel–blockers are used to treat hypertension, angina, heart arrhythmias, and other heart-related conditions.

Examples of drugs in this family include:

• Amlodipine (Norvasc)
• Bepridil hydrochloride (Vascor)
• Diltiazem (Cardizem, Cardizem CD, Cardizem SR, Dilacor XR, Tiamate, Tiazac)
• Felodipine (Plendil)
• Isradipine (DynaCirc, DynaCirc CR)
• Nicardipine hydrochloride (Cardene, Cardene SR)
• Nifedipine (Procardia, Procardia XL, Adalat, Adalat CC)
• Nimodipine (Nimotop)
• Nisoldipine (Sular)
• Verapamil (Calan, Calan SR, Covera-HS, Isoptin, Isoptin SR, Verelan)

  Calcium and Vitamin D

Possible Decreased Action of Drug

Taking calcium and vitamin D supplements might interfere with some of the effects of calcium channel-blockers.^1-7 

  Ginkgo Biloba

Possible Decreased Action of Drug

According to a study in rats, ginkgo extract may cause the body to metabolize some calcium channel blockers more rapidly, thereby decreasing their effects.8 

  Naringen (a Citrus Bioflavonoid)

May Necessitate Reduction in Drug Dosage

Some evidence suggests that the bioflavonoid naringen may interact with medications in the calcium channel blocker family, increasing blood levels of the drug.⁹  This may necessitate a reduction in drug dosage.

References [ + ]

1. Bar-Or D and Gasiel Y. Calcium and calciferol antagonise effect of verapamil in atrial fibrillation. Br Med J (Clin Res Ed). 1981;282:1585-1586.

2. Hariman RJ, Mangiardi LM, McAllister RG Jr, et al. Reversal of the cardiovascular effects of verapamil by calcium and sodium: differences between electrophysiologic and hemodynamic responses. Circulation. 1971;59:797-804.

3. Guadagnino V, Greengart A, Hollander G, et al. Treatment of severe left ventricular dysfunction with calcium chloride in patients receiving verapamil. J Clin Pharmacol. 1987;27:407-409.

4. Salerno DM, Anderson B, Sharkey PJ, et al. Intravenous verapamil for treatment of multifocal atrial tachycardia with and without calcium pretreatment. Ann Intern Med. 1987;107:623-628.

5. Luscher TF, Noll G, Sturmer T, et al. Calcium gluconate in severe verapamil intoxication. N Engl J Med. 1994;330:718-720.

6. Orr GM, Bodansky HJ, Dymond DS, et al. Fatal verapamil overdose. Lancet. 1982;2:1218-1219.

7. Kuhn M and Schriger DL. Low-dose calcium pretreatment to prevent verapamil-induced hypotension. Am Heart J. 1992;124:231-232.

8. Shinozuka K, Umegaki K, Kubota Y, et al. Feeding of Ginkgo biloba extract (GBE) enhances gene expression of hepatic cytochrome P-450 and attenuates the hypotensive effect of nicardipine in rats. Life Sci. 2002;70:2783-2792.

9. Yeum CH, Choi JS. Effect of naringin pretreatment on bioavailability of verapamil in rabbits. Arch Pharm Res. 2006;29:102-107.

Last reviewed July 2012 by EBSCO CAM Review Board
Last Updated: 7/25/2012

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