Determination of fluoxetine and its N-desmethyl metabolite in human plasma by high-performance liquid chromatography.
ABSTRACT A rapid and sensitive high-performance liquid chromatographic method has been developed for the simultaneous determination of the antidepressant fluoxetine and its active metabolite norfluoxetine in human plasma using paroxetine as internal standard. After liquid-liquid extraction, the compounds were separated on a C18 column using as mobile phase acetonitrile and 40mM potassium dihydrogen phosphate buffer (pH 2.3) in the ratio 31:69 (v/v). The quantification of fluoxetine and norfluoxetine was made by fluorescence detection at Ex/Em 230/312nm. The assay for each analyte was linear over the ranges 1-39 and 0.9-36ng/ml, respectively. For both compounds intra- and inter-day accuracy and precision ranged between -7.9-12.4 and 0.7-14.7%, respectively. The method was applied to the analysis of plasma samples obtained from healthy subjects treated with one single oral dose of 40mg fluoxetine.
Article: A novel chiral GC/MS method for the analysis of fluoxetine and norfluoxetine enantiomers in biological fluids.[show abstract] [hide abstract]
ABSTRACT: A novel robust chiral gas chromatographic/mass spectrometric (GC/MS) method for the separation and measurement of fluoxetine and norfluoxetine enantiomers in urine and plasma was developed. The drug was extracted from the samples by a liquid-liquid technique, using chloroform, and the enantiomers were separated and measured on a chiral gas chromatographic column (HYDRODEX β-6TBDM(®), 0.25 μm × 0.25 mm × 50 m). GC/MS instrumentation was used for the acquisition of data in the electron impact selective-ion monitoring mode. The ions chosen were of a mass-to-charge ratio (m/z) exactly equal to 44 units, in order to measure fluoxetine enantiomers, 134 units in order to measure norfluoxetine enantiomers, and 58 units in order to measure diphenhydramine, the internal standard. The method was found to be linear and reproducible in the 50-500 ng/mL concentration range for both urine samples and plasma samples and for both fluoxetine and norfluoxetine, with correlation coefficients ranging between 0.994 and 0.997. This methodology has an enormous potential for application in pharmacokinetic studies of the enantiomers of fluoxetine.Journal of pharmacy & bioallied sciences. 07/2012; 4(3):236-45.