Comparison of fibrinolytic and immunodetection methods for the measurement of APSAC pharmacokinetics in patients with acute myocardial infarction

Abstract

The pharmacokinetics of anisoylated lys-plasminogen streptokinase activator complex in AMI patients have been investigated using the fibrin plate assay and a novel antigen assay. The average initial half-life for clearance of total fibrinolytic activity in euglobulin fractions, quantifiable from 6 min to 6 h post-dosing, was 68 ± 7 min (n = 7). The molar concentration of SK antigen in whole plasma, at each time point, was greater than apparent from fibrinolytic activity measurements; SK antigen remained at the starting level for the first hour and was measurable up to 9 h post-dosing. However, the rate of disappearance of SK antigen from 1 h onwards was of the same order, 98 ±min (n = 5) as that found for fibrinolytically active material. We conclude that, after deacylation of the proenzyme, loss of fibrinolytic activity occurs by inactivation within the bloodstream rather than, initially, by tissue uptake.