Evaluation of the pharmacokinetic and pharmacodynamic interaction between quinidine and nifedipine

J Clin Pharmacol. 1993 Aug;33(8):727-31. doi: 10.1002/j.1552-4604.1993.tb05614.x.


Quinidine and nifedipine appear to be subject to metabolism by the same isozyme of cytochrome P-450. In addition, both drugs have been reported to alter the pharmacokinetics of other compounds. To investigate a potential interaction, 10 healthy subjects (five male, five female) received quinidine sulfate (200 mg orally), nifedipine (20 mg orally), or the combination of both drugs every 8 hours for 4 doses using a randomized, cross-over study design with a 2-week washout period between treatments. Drug concentration, heart rate, and mean arterial pressure were measured at frequent intervals after the final dose. Quinidine concentrations were unchanged by the co-administration of nifedipine. Nifedipine area under the curve (AUC0-8) increased 36.6% from 333 to 455 micrograms.hr/L (P < .05) after quinidine administration. Heart rate was significantly higher in the nifedipine-quinidine treatment at 0.5, 1.0, 1.5, and 2.0 hours when compared with either drug alone. The maximum increase in heart rate (17.9 beats/minute) occurred at 0.5 hours after nifedipine administration and was significantly correlated with serum concentrations at that time (r = .78). These results suggest that quinidine inhibits nifedipine metabolism, and this pharmacokinetic interaction results in enhanced pharmacologic response.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Blood Pressure / drug effects
  • Drug Interactions
  • Drug Therapy, Combination
  • Female
  • Heart Rate / drug effects
  • Humans
  • Male
  • Nifedipine / antagonists & inhibitors*
  • Nifedipine / pharmacokinetics
  • Nifedipine / pharmacology
  • Quinidine / pharmacokinetics
  • Quinidine / pharmacology*


  • Nifedipine
  • Quinidine