Micellar electrokinetic chromatographic method for the determination of letrozole, citalopram and their metabolites in human urine.

A new micellar electrokinetic chromatographic method has been developed to analyse human urine samples containing a combination of a drug used for the treatment of breast cancer (letrozole), an antidepressant (citalopram) and their main metabolites. Best results were obtained by using 15 mM borate buffer (pH 9.2) containing 20 mM sodium dodecyl sulphate and 12% (v/v) 2-propanol as the background electrolyte. The separation was performed through a fused silica capillary at 40 degrees C with the application of 6s (3.45 kPa) of hydrodynamic injection and 30 kV of separation voltage. Detection wavelength was 240 nm. Under these conditions, the migration times for all the studied compounds were ranged between 3.0 and 8.0 min. Linearity ranges were determined as 0.4-5.0 microg/mL for all the compounds. Detection limits between 12.5 and 25 ng/mL were determined in urine samples. According to the validation study, the developed method has been proven to be accurate, precise, sensitive, specific, rugged and robust. This method has been used to determine letrozole, citalopram and their metabolites in human urine at clinical levels. Prior to determination, the samples are purified and enriched by means of an extraction-preconcentration step with a preconditioned C(18) cartridge and by eluting the compounds with methanol. The developed method was applied to the determination of these analytes in three urine samples from patients undergoing treatment with letrozole or citalopram.

Assay validation for three antidepressants in pharmaceutical formulations: practical approach using capillary gas chromatography.

An easy and fast capillary gas chromatographic FID method, which was already described by the same authors for the simultaneous determination of fluoxetine, fluvoxamine and clomipramine without derivatization step, is now submitted to a validation procedure in several pharmaceutical formulations. Main aspects of the validation method are examined and discussed, since methods for regulatory submission in most cases must demonstrate: specificity in presence of all potential components, concentration range over which the response is lineal, accuracy, precision, acceptable detection and quantitation limits and stability of the procedure. The pharmaceutical preparations subject of validation were: 'Prozac' (capsules), 'Dumirox' (tablets) and 'Anafranil' (tablets) containing fluoxetine, fluvoxamine and clomipramine, respectively. The results presented in this report show the applied gas chromatographic method is acceptable for the determination of the three antidepressants in the pharmaceutical formulations above mentioned.