Development of an ELISA for the measurement of DSPA α1 ( Desmodus rotundus salivary plasminogen activator) in plasma and its application to investigate pharmacokinetics in monkeys

Abstract

DSPAα1 is a novel plasminogen activator with high fibrin specificity. A sandwich ELISA-system with affinity purified and peroxidase labelled DSPAα1 antibodies raised in rabbits was developed and exhibited a limit of quantification of 3 ng/ml in undiluted spiked plasma. Accuracy was 98–108% and precision accounted for 3–9.5%. No cross-reactivity with human t-PA or endogenous matrix constituents interfering with assay results was observed. After i.v. administration DSPAα1 at 1 and 3 mg/kg in cynomolgus monkeys antigen levels in plasma were dose-dependent in both gender and exhibited a triphasic disposition profile with half-lives of 0.04–0.26 h, 0.6–3 h and 4–8.5 h. The mean residence time of DSPAα1 ranged from 3 to 9 h and total clearance was approximately 2 ml/min/kg independent of sex and dose. These data obtained in monkeys showed a long systemic circulation of the antigen, linear pharmacokinetics and no sex-specific pharmacokinetic differences in the dose range investigated. In conclusion the present ELISA method is suitable for pharmacokinetic studies of DSPAα1 in animals and man. First investigations in monkeys demonstrated the interesting pharmacokinetic profile of the compound which might be administered by i.v. bolus administration for the treatment of acute myocardial infarction.