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 verapamil and quinidine are taken together, your body may not process quinidine properly and your blood levels of quinidine may increase. When nifedipine and quinidine are taken together, your body may not process quinidine properly and your blood levels of quinidine may increase or decrease. Quinidine may cause your body to process nifedipine more slowly and increase your blood levels of nifedipine.
What might happen:
If you are taking verapamil and quinidine, you may experience a decrease in blood pressure. If you are taking nifedipine and quinidine, you may experience an increase or decrease in the effects of quinidine on your heart and an increase in the effects of nifedipine. If nifedipine is stopped, you may experience a decrease in your blood levels of quinidine.
What you should do about this interaction:
If you are taking verapamil and quinidine and you experience weakness, fatigue, or dizziness, contact your doctor. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose of one or both of your medicines.If you are taking nifedipine and quinidine and you notice a fast or irregular heartbeat, contact your doctor. It may be necessary to measure your blood levels of quinidine more often. Your doctor may need to adjust the dose of one or both of your medicines. If your doctor stops your nifedipine and you experience nausea, vomiting, stomach pain, drowsiness, trouble breathing, ringing in the ears, vision problems, dizziness, or headache, contact your doctor.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Epstein SE, Rosing DR. Verapamil: its potential for causing serious complications in patients with hypertrophic cardiomyopathy. Circulation 1981 Sep;64(3):437-41.
2.Mitchell LB, Schroeder JS, Mason JW. Comparative clinical electrophysiologic effects of diltiazem, verapamil and nifedipine: a review. Am J Cardiol 1982 Feb 18;49(3):629-35.
3.Green JA, Clementi WA, Porter C, Stigelman W. Nifedipine-quinidine interaction. Clin Pharm 1983 Sep-Oct;2(5):461-5.
4.Farringer JA, Green JA, O'Rourke RA, Linn WA, Clementi WA. Nifedipine-induced alterations in serum quinidine concentrations. Am Heart J 1984 Dec;108(6):1570-2.
5.Maisel AS, Motulsky HJ, Insel PA. Hypotension after quinidine plus verapamil. Possible additive competition at alpha-adrenergic receptors. N Engl J Med 1985 Jan 17;312(3):167-70.
6.Ochs HR, Anda L, Eichelbaum M, Greenblatt DJ. Diltiazem, verapamil, and quinidine in patients with chronic atrial fibrillation. J Clin Pharmacol 1985 Apr;25(3):204-9.
7.Van Lith RM, Appleby DH. Quinidine-nifedipine interaction. Drug Intell Clin Pharm 1985 Nov;19(11):829-31.
8.Edwards DJ, Lavoie R, Beckman H, Blevins R, Rubenfire M. The effect of coadministration of verapamil on the pharmacokinetics and metabolism of quinidine. Clin Pharmacol Ther 1987 Jan;41(1):68-73.
9.Bigger JT, Hoffman BF. Antiarrhythmic drugs. In Gilman AG, Goodman LS, Rall TW, Murad F, eds. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 7th ed. New York: MacMillan Publishing Company. 1985.
10.Lavoie R, Blevins RD, Rubenfire M, Edwards DJ. The effect of verapamil on quinidine pharmacokinetics in man. Clin Pharmacol Ther 1986 Jun;20:457.
11.Trohman RG, Estes DM, Castellanos A, Palomo AR, Myerburg RJ, Kessler KM. Increased quinidine plasma concentrations during administration of verapamil: a new quinidine-verapamil interaction. Am J Cardiol 1986 Mar 1;57(8):706-7.
12.Munger MA, Jarvis RC, Nair R, Kasmer RJ, Nara AR, Urbancic A, Green JA. Elucidation of the nifedipine-quinidine interaction. Clin Pharmacol Ther 1989 Apr;45(4):411-6.
13.Schellens JH, Ghabrial H, van der Wart HH, Bakker EN, Wilkinson GR, Breimer DD. Differential effects of quinidine on the disposition of nifedipine, sparteine, and mephenytoin in humans. Clin Pharmacol Ther 1991 Nov;50(5 Pt 1):520-8.
14.Bowles SK, Reeves RA, Cardozo L, Edwards DJ. Evaluation of the pharmacokinetic and pharmacodynamic interaction between quinidine and nifedipine. J Clin Pharmacol 1993 Aug;33(8):727-31.
15.Bailey DG, Freeman DJ, Melendez LJ, Kreeft JH, Edgar B, Carruthers SG. Quinidine interaction with nifedipine and felodipine: pharmacokinetic and pharmacodynamic evaluation. Clin Pharmacol Ther 1993 Mar;53(3):354-9.
16.Cardizem LA (diltiazem hcl extended release tablets) US prescribing information. Abbott Pharmaceuticals, Inc. March, 2015.
17.Karch M, Schmitt C, Plewan A, Schmidt G, Schomig A. Torsade de pointes tachycardia during administration of quinidine and verapamil in atrial fibrillation. Herz 1997 Feb;22(1):51-6.
18.Laganiere S, Davies RF, Carignan G, Foris K, Goernert L, Carrier K, Pereira C, McGilveray I. Pharmacokinetic and pharmacodynamic interactions between diltiazem and quinidine. Clin Pharmacol Ther 1996 Sep; 60(3):255-64.
19.Hippius M, Henschel L, Sigusch H, Tepper J, Brendel E, Hoffmann A. Pharmacokinetic interactions of nifedipine and quinidine. Pharmazie 1995 Sep;50(9):613-6.