SIMPLIFIED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF CITALOPRAM AND DESMETHYLCITALOPRAM IN SERUM WITHOUT INTERFERENCE FROM COMMONLY USED PSYCHOTROPIC-DRUGS AND THEIR METABOLITES

A simplified method for the determination of racemic citalopram and it s main metabolite desmethylcitalopram in serum using HPLC was develope d. The compounds were extracted with heptane-isoamyl alcohol (98:2) an d subsequently transferred into phosphate buffer pH 2.5 for direct inj ection into the HPLC apparatus. The analytes were separated with an ac etonitrile-phosphate buffer, pH 2.5-tetraethylamine mobile phase on a C-18 column and measured by UV detection at 240 nm. Within the typical range of serum concentrations (30-200 ng/ml) the inter-day variation was <6% for both compounds. Possible analytical interference from a nu mber of commonly coadministered psychoactive drugs and their metabolit es was studied by extracting sera from patients receiving these drugs. Interference was not a problem for the developed method.