Quantitative determination of imidazenil, a novel imidazobenzodiazpine carboxamide derivative, by normal phase...

Imidazenil, an imidazobenzodiazepine carboxamide derivative, is a novel anxiolytic and anti-convulsant agent recently characterized as a partial allosteric modulator of GABAA receptors. Owing to the pharmacological and pharmacokinetic importance of plasma-level determination, a HPLC method has been developed. Imidazenil was extracted from a plasma sample after a partition with diethyl ether, using alprazolam as internal standard. The analysis was performed by a normal-phase HPLC method with UV detection at 255 nm. The limit of quantitation was 6 ng corresponding to 30 ng/ml of plasma concentration. This procedure has been successfully applied to the quantitation of imidazenil plasma levels in primarily pharmacokinetic studies after a single i.v. and an oral administration of the compound to the rat.