[The pharmacokinetics and the concentration-and-effect relationship of prazosin in patients at the beginning of the subacute period of myocardial infarct complicated by the development of heart failure].

The pharmacokinetics of prazosin was studied in 16 patients in the early subacute period of myocardial infarction complicated with heart failure following a single and 10-day administration. The increase of the half-life of the drug (6.6 +/- 1.6 h) and the elevation of the blood plasma concentration 1-2.5 h after administration (87 +/- 33 ng/ml) were found. After 10-day administration the increase of the apparent total clearance of the drug was established. The blood plasma levels of prazosin significantly correlated with the change of the hemodynamic parameters measured invasively after a single administration of 2-5 mg of the drug. After 10 days of treatment the correlation weakened and the regression line angle reduced that reflected the development of tolerance to the drug. On the basis of the calculated effective concentrations, there were determined the optimal intervals of the drug dosage.