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Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic solvent used as supported liquid membranes (SLMs), and into 50μL aqueous acceptor solutions. The acceptor solutions were subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using in-source fragmentation and monitoring the m/z 184→184 transition for investigation of phosphatidylcholines (PC), sphingomyelins (SM), and lysophosphatidylcholines (Lyso-PC). In both generic methods, no phospholipids were detected in the acceptor solutions. Thus, PALME appeared to be highly efficient for phospholipid removal. To further support this, qualitative (post-column infusion) and quantitative matrix effects were investigated with fluoxetine, fluvoxamine, and quetiapine as model analytes. No signs of matrix effects were observed. Finally, PALME was evaluated for the aforementioned drug substances, and data were in accordance with European Medicines Agency (EMA) guidelines., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A simple and selective (19)F NMR method has been validated for the quantitation of fluoxetine (FLX) and fluvoxamine (FLV) in methanol solutions and in human plasma and urine. The regression equations for FLX and FLV showed a good linearity in the range of 1.4-620 microg mL(-1) (3.3 x 10(-6)-1.8 x 10(-3) mol L(-1)) with a limit of detection of approximately 0.5 microg mL(-1) (1.3 x 10(-6) mol L(-1)) and a limit of quantification of approximately 2 microg mL(-1) (4.6 x 10(-6) mol L(-1)). The precision of the assay depends on the concentrations and is comprised between 1.5 and 9.5% for a range of concentrations between 1.2 x 10(-3) and 3.2 x 10(-6) mol L(-1). The accuracy evaluated through recovery studies ranged from approximately 96 to 103% in methanol solutions and in urine, and from approximately 93 to 104% in plasma, with standard deviations <7.5%. The low sensitivity of the method precludes its use for the assay of these antidepressants in biofluids at least at therapeutic doses as the ranges of FLX and FLV plasma levels are 0.15-0.5 microg mL(-1) and 0.15-0.25 microg mL(-1), respectively. The method was applied successfully to the determination of FLX and FLV contents in pharmaceutical samples (brand-named and generic) purchased in several countries or via the Internet. All the commercial formulations contain the active ingredient in the range 94-103% of stated concentration. A "signature" of the formulations (solid and liquid) was obtained with 2D Diffusion-Ordered SpectroscopY (DOSY) (1)H NMR which allowed the characterisation of the active ingredient and excipients present in the formulations studied. Finally, the DOSY separation of FLX and FLV whose molecular weights are very close was obtained by using beta-cyclodextrin as host-guest complexing agent.

Fluoxetine hydrochloride has been prepared using two similar synthetic routes, both of which rely upon an ether formation reaction mediated by a base. The base used can affect the impurity profile of this reaction. It was proposed that the synthesis of fluoxetine carried out using potassium t-butoxide as base and 4-chlorobenzotrifluoride (or 4-fluorobenzotrifluoride) in the ether formation step may result in the formation of 4-benzotrifluoride t-butyl ether as a reaction by-product. To test this hypothesis, capillary gas chromatography-mass spectrometry (GC/MS) was utilized to evaluate samples of free base fluoxetine synthesized using sodium hydride (NaH) or potassium t-butoxide as the base. Assay conditions using selected ion monitoring (SIM) were developed, which allowed detection of trace levels (parts per million, ppm) of 4-benzotrifluoride t-butyl ether in fluoxetine free base sample matrix. Response linearity, precision, and standard spike recovery were examined during development, and were found to be suitable. Comparisons of fluoxetine samples generated from both NaH and potassium t-butoxide processes were performed using the GC/MS assay.

A simple, accurate and sensitive high pressure liquid chromatographic technique is described for the determination of fluoxetine in the capsule dosage form, human plasma and in biological fluid. Analysis is performed with a reversed phase-C18 column with ultraviolet detection at 228 nm. The isocratic mobile phase (1.5 ml/min.) consists of acetonitrile and triethylamine buffer (48 + 52, V/V). A linear calibration model (correlation coefficient 0.99863) was developed using pyridoxine as internal standard. The retention times were 2.10 and 3.20 min for pyridoxine and fluoxetine, respectively. The method was applied for the quantitation of fluoxetine in spiked human plasma samples. The detection limit is 5 microg/l and the absorbance varies with fluoxetine concentrations in the range (10-300) microg/l. The mean % recovery +/- S.D. was found to be 97.99% +/- 2.39. The proposed method was applied successfully for monitoring of fluoxetine in human plasma after single dose administration of one prozac capsule., (Copyright 2002 Elsevier Science B.V.)

Eriochrome cyanine R (ECR) reacts with fluvoxamine (FXM) and fluoxetine (FXT) forming coloured ion-association compounds. The composition of the compounds, studied by spectrophometric methods showed that the molar ratio ECR:FXM = 1:2 and ECR:FXT = 1:2. The formation and extraction conditions of the compounds were established. The compounds were characterised by UV, VIS, and IR spectrometry. It was found that the compounds are insoluble in water but quantitatively extracted into buthanol. Under the optimal experimental conditions fluvoxamine and fluoxetine were determined in the range 2-40 microg/ml and 2-20 microg/ml, respectively. The relative standard deviation is about +/- 2%.

Two new rapid, sensitive and economical spectrophotometric methods are described for the determination of fluoxetine hydrochloride in bulk and in pharmaceutical formulations. Both methods are based on the formation of a yellow ion-pair complex due to the action of methyl orange (MO) and thymol blue (TM) on fluoxetine in acidic (pH 4.0) and basic (pH 8.0) medium, respectively. Under optimised conditions they show an absorption maxima at 433 nm (MO) and 410 nm (TB), with molar absorptivities of 2.12 x 10(-4) and 4.207 x 10(-3) l mol(-1) cm(-1) and Sandell's Sensitivities of 1.64 x 10(-2) and 0.082 microg cm(-2) per 0.001 absorbance unit for MO and TB, respectively. The colour is stable for 5 min after extraction. In both cases Beer's Law is obeyed at 1-20 microg mol(-1) with MO and 4-24 microg mol(-1) with TB. The proposal method was successfully extended to pharmaceutical preparations capsules. The results obtained by both the agreement and E.P. (3rd edition) were in good agreement and statistical comparison by Student's t-test and variance ratio F-test showed no significant difference in the three methods.

Chromatographic methods using chiral stationary phases have been developed for the separation of fluoxetine hydrochloride enantiomers. Ovomucoid and tris(3,5-dimethylphenyl carbamate) cellulose stationary phases were used in the reversed- and normal-phase modes, respectively. Acceptable isomer separation was achieved at pH 3.5 with the ovomucoid phase. Isopropyl alcohol and methyl-tert- butyl ether mobile phase modifiers each provide complete resolution using the derivatized cellulose column. Better separation robustness was obtained with a column temperature of 1 degree C the isopropyl alcohol modifier. The methyl-tert-butyl ether system was robust at room temperature. Differences in relative enantiomer amounts of as little as 2% could be determined. The chromatographic conditions provided a much more discriminating test compared to an optical rotation method proposed for pharmacopeial use which had difficulty distinguishing individual enantiomers. The chiral chromatographic conditions were also applied to capsule formulations to demonstrate the presence of racemic fluoxetine hydrochloride.