An indirect sandwich ELISA for the determination of agkisacutacin in human serum: Application to pharmacokinetic study in Chinese healthy volunteers

The platelet receptor glycoprotein Ib-IX-V complex (GPIb-IX-V) plays a dominant role in the first step of platelet adhesion and arterial thrombus formation. Agkisacutacin, a C-type lectin-like protein (CLP) from Agkistrodon acutus venom, had been previously identified as an antagonist of platelet aggregation and a membrane glycoprotein Ib-binding protein (GPIb-bp). For the analysis of pharmacokinetics of agkisacutacin, an indirect sandwich enzyme-linked immunosorbent assay (ELISA) was established and validated to quantify agkisacutacin in human serum. The method was precise and accurate over the entire linear range of 1.0 and 1000 pg/mL with a lower limit of quantification of 1.0 pg/mL. The intra- and inter-assay coefficient of variation ranged from 0.7 to 4.2% and 1.1 to 4.1%, respectively. Recovery obtained from the accuracy test, using three concentration levels, varied between 96.1 and 110.6%, confirming the assay's reliability. The long-term study showed agkisacutacin was stable at −70 °C up to 46 days. This ELISA was first used to assess the pharmacokinetics of agkisacutacin in healthy volunteers. The characteristics of pharmacokinetic showed that agkisacutacin could rapidly combine with GPIb and slowly dissociate from GPIb-bound form in the body.