Ethnic differences in nifedipine pharmacokinetics and pharmacodynamics: Comparison of middle eastern arabs with other populations

Department of Clinical Pharmacy, College of Pharmacy, King Saud University, P.O.Box 2457, Riyadh 11451. Military Hospital, Riyadh, Kingdom of Saudi Arabia.The pharmacokinetics and pharmacodynamic effects of oral nifedipine were studied in five healthy male Middle Eastern Arab subjects and their results were compared with those reported for other populations. Each subject received a single 2* 10-mg dose under fasting conditions and plasma concentrations were determined by a specific HPLC method. Heart rate and systolic and diastolic blood pressure were also monitored. The elimination half-life, maximum plasma concentration and time to maximum plasma concentration were found to be 3.20±0.21 h, 230.4±36.4 ng/ml and 0.95±0.23 h, respectively. Mean residence time (MRT) and operative clearance (CL/F) were determined to be 3.82±0.67 h and 0.30±0.06 L/h.kg, respectively. Plasma concentrations in Middle Eastern Arab subjects were similar to those reported for South Asians, Japanese and Nigerians, but they were significantly higher than in Caucasians. The AUC and normalized AUC were 2.8 and 3.4 folds greater in Middle Eastern Arab subjects than in Caucasians. The hemodynamic effects of nifedipine were comparable in all ethnic groups studied. In conclusion, Middle Eastern Arab patients should be initiated with a lower dose than would be administered to Caucasians