Pharmacokinetics of cytotoxin from Chinese cobra (Naja naja atra) venom.

The pharmacokinetics of cytotoxin from Chinese cobra (Naja naja atra) venom was studied in rabbits after i.v. and i.m. injection of 0.2 and 0.5 mg.kg-1, respectively. The plasma levels of the cytotoxin were analysed by a biotin-avidin enzyme-linked immunosorbent assay. The plasma concentration-time course after i.v. administration fitted a two-compartment open model. The half-life (mean +/- S.D.) of the alpha-phase was 5.8 +/- 0.6 min and that of the beta-phase 3.5 +/- 0.2 hr. Apparent volume of distribution was 1.7 +/- 0.3 litres.kg-1, and clearance was 5.6 +/- 1.4 ml.min-1. A rapid absorption was observed after i.m. injection with peak plasma level of 260 +/- 90 ng.ml-1 reached within 13.6 +/- 2.4 min. The absorption rate constant was 0.16 +/- 0.03 ml-1. The area under the plasma concentration-time curve was 33 +/- 15 micrograms.min.ml-1.