An Assay Method for Trasylol® Based on the In Vitro Inhibition of Human Plasma Kallikrein

Plasma kallikrein prepared by activation of citrated plasma with acetone (16.7 % v/v) for 17 hours at room temperature (20–24°) was preincubated with trasylol for 10 minutes (37°). Kinin release was obtained by incubation for 30 minutes (37°) with citrated human plasma in which the kininase had been eliminated with EDTA‐2Na (4 mg per ml) for 30 minutes (37°), and in which the acetone‐susceptible kallikrein inhibitors had been depressed immediately before by the addition of acetone (12.5 % v/v). The reaction was stopped by heating for 30 minutes (100°) after which the released kinin was assayed on the isolated rat uterus. Ten different trasylol samples were estimated against a standard trasylol in (2 + 2) assays with a dose ratio 1:0.5 and with 6 series of 4 doses. The average departure from the true trasylol content was 5.4 % (range — 8.8 to + 11.1 %) and the mean systematical deviation was + 0.4 %. The fiducial limits ranged from 95–105 % to 89–112 % (P = 0.05), and s/b was 0.035 (range 0.024 to 0.053).