ROUTINE MEASUREMENT OF FLUOXETINE AND NORFLUOXETINE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION IN PATIENTS UNDER CONCOMITANT TREATMENT WITH TRICYCLIC ANTIDEPRESSANTS

A robust and rapid high-performance liquid chromatography (HPLC) metho d is described for therapeutic drug monitoring of fluoxetine and norfl uoxetine in the presence of six frequently-used tricyclic antidepressa nts and their respective metabolites. Liquid-liquid extraction into n- hexane/acetonitrile is used with reextraction into hydrochloric acid f or clean-up. The chromatographic separation is carried out on a CN col umn. The minimum detectable amount is 3 ng injected on column. In addi tion to qualitative and quantitative validation data for the assay met hod, results from patient samples are presented. It is concluded that for patients treated with fluoxetine, therapeutic drug monitoring is v aluable for optimizing the therapy.