Simultaneous determination of the two components of picrotoxin in serum by reversed-phase high-performance liquid chromatography with application to a pharmacokinetic study in rats.

A reversed-phase HPLC method is reported which allows the quantification of picrotin and picrotoxinin in serum. A linear response was obtained for both drugs in the range 0.2-20 micrograms ml-1. The within-day and between-day precisions were 0.8-3.7% and 1.3-4.9%, respectively. The mean recoveries were greater than 94.2%. The method was applied to a pharmacokinetic study following intraperitoneal (i.p.) administration of 3 mg kg-1 of picrotoxin in rats. The obtained data suggest a relatively slow absorption after i.p. administration followed by a rapid elimination from the central compartment according to a one-compartment open model. The elimination half-lives were 0.340 +/- 0.0308 h for picrotin and 0.312 +/- 0.0241 h for picrotoxinin.