Extraction and quantification of epibatidine in plasma

Epibatidine was extracted from human and mouse plasma into a hexane-isopropanol mixture and back-extracted into a phosphate buffer, pH 2.5, then identified by HPLC isocratically using a CN column and quantified with ultraviolet detection at a fixed wavelength of 214 nm. The percent recovery of epibatidine from spiked plasma samples was 83.6% and the percent extraction was linear between 10 and 1,000 ng/ml. Desipramine was used as the internal standard. For spiked control samples containing 50 and 750 ng/ml, between-day precisions were 20.8 and 7.2% (RSD%), respectively; accuracy was 87.0 and 99.1%, respectively. The limit of detection was 2 ng/ml. Using this method, an intraperitoneal dose of 0.1 mg/kg of epibatidine produced mean levels of 7.3 and 37.1 ng/ml in pooled male and female plasma samples from C57BL/10 J mice, respectively. This is a simple and straightforward procedure by which plasma samples may be analyzed for epibatidine.