DETERMINATION OF ALPRAZOLAM AND ITS MAJOR METABOLITES IN SERUM MICROSAMPLES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND ITS APPLICATION TO PHARMACOKINETICS IN RATS

A high-performance liquid chromatographic method using a single-solven t extraction step is described for quantitating alprazolam and its met abolites in rat serum microsamples (50 mul). The separation used a 2-m m I.D. reversed-phase Ultrasphere C18 column with a mobile phase of me thanol-acetonitrile-sodium acetate buffer. By decreasing the methanol content in the mobile phase, triazolam and its metabolites can be extr acted and separated using the same method. The detection limit was 5 n g/ml for all the compounds using an ultraviolet detector at 230 nm. Th e method showed the effect of aging on alprazolam pharmacokinetics fol lowing 0.8 mg/kg intravenous bolus alprazolam administration.