The pharmokinetics of isradipine in hypertensive subjects

In conjunction with a multicentre clinical trial of the calcium antagonist isradipine in hypertension, pharmacokinetic and pharmacodynamic studies were conducted in 9 subjects. An initial dose of 5 mg (capsule formulation) of isradipine was given orally. The mean Cmax, tmax and AUC(0-8) were 6.0 ng.ml-1, 1.5 h and 15.1 h.ng.ml-1 respectively. Seven subjects repeated the study at steady state after 10 week's dose titration with isradipine. Cmax, tmax and AUC(0-8) were 3.7 ng.ml-1, 1.2 h and 12.2 h.ng.ml-1 respectively indicating that the drug does not accumulate over time. Control of blood pressure paralleled plasma isradipine concentrations which suggested that the drug should be given at least twice daily. Pharmacokinetic studies performed in conjunction with clinical trials can provide valuable information about the patterns of drug response.