Relationship between pharmacokinetics and hemodynamic tolerance to isosorbide-5-mononitrate

Healthy male volunteers received three different dose regimens of a controlled-release form of isosorbide-5-mononitrate (IS-5-MN; 60 mg per tablet). Dose regimen I consisted of a single daily dose of 60 mg given for 5 days. Dose regimen II was started with a dose of 60 mg, followed by 30 mg 12 h later and thereafter every 8 h. The last dose, on the 5th day was again 60 mg. In dose regimen III 60 mg followed by 30 mg 6 h later were administered every day for 5 days. The peripheral arterial and venous effects of IS-5-MN during the first and last dosing interval were followed by changes in the finger pulse curve, standing systolic blood pressure, heart rate, and venous distensibility. Plasma concentrations of IS-5-MN were measured frequently following the first and the last dose. Following dose regimen I all hemodynamic effects produced by the first dose were maintained during the study. The maximal plasma concentrations were about 400 ng/ml and the trough value, lower than 100 ng/ml. Following dose regimen II the hemodynamic effects of IS-5-MN and sublingual glyceroltrinitrate were completely abolished on the 5th day. Trough plasma concentrations were approximately 300 ng/ml during the entire study period. Following dose regimen III pronounced hemodynamic effects were seen on the 1st day. However, a significant attenuation of the hemodynamic effects was measured on the 5th day, when trough plasma concentrations were between 100 and 230 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)