DETERMINATION OF OLANZAPINE IN SERUM BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING ULTRAVIOLET DETECTION CONSIDERING THE EASY OXIDIZABILITY OF THE COMPOUND AND THE PRESENCE OF OTHER PSYCHOTROPIC-DRUGS

A method for determination of the atypical neuroleptic drug olanzapine in serum was developed. After a single-step liquid-liquid extraction, the compound was separated from other constituents on a normal-phase silica gel column using a buffer-methanol mobile phase and measured by UV absorption at 270 nm. Addition of 0.25% ascorbic acid to serum pro tects olanzapine against oxidation during extraction and stabilizes th e easily oxidised compound during storage. Inter-day variation was <8% at serum levels found in olanzapine treated patients. Analytical inte rference from coadministered psychoactive drugs and their metabolites were studied. Only risperidone, also a relatively newly developed anti psychotic drug, interfered, but the most commonly used antidepressants and traditional antipsychotics and their metabolites did not interfer e. (C) 1998 Elsevier Science B.V. All rights reserved.