GAS-CHROMATOGRAPHIC ASSAY FOR ESTAZOLAM IN HUMAN PLASMA AND RESULTS OF A BIOEQUIVALENCE STUDY

This paper describes a new sensitive gas chromatographic method with e lectron capture detector to assay estazolam in human plasma, which has been developed and validated for pharmacokinetic purposes. The drug a nd the internal standard (triazolam) were extracted from plasma buffer ed at pH 9.0 into toluene and analysed on a widebore DB 17 column. The calibration curve covered the 1.0-200 ng ml(-1) range with a mean det ermination coefficient of 0.9996. The quantification limit was 1.0 ng ml(-1). This method was used to investigate the bioequivalence of a ne w formulation of estazolam in drops (test) and the formulation in tabl ets (reference, ESILGAN(R)). Both formulations were administered at a single dose of 2 mg in a clinical trial carried out on 24 healthy volu nteers consisting of 12 males and 12 females, following a crossover ra ndomised design in two periods with wash-out, The test and the referen ce formulations proved to be fully bioequivalent according to operatin g guidelines, namely through 90% confidence intervals in the 0.80-1.25 range. (C) 1997 The Italian Pharmacological Society.