Search

A black phosphorus (BP)-nanosheet-based drug-delivery system containing a therapeutic drug (Fluoxetine, Flu) is synthesized. According to subsequent behavioral, biochemical, and electrophysiological analysis, BP-Flu, after irradiated with near-infrared light (808 nm), can significantly reduce the therapy time of depression. Meanwhile, the inherent biotoxicity of Flu is also alleviated., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A general method for the synthesis of [(18) F]difluoromethylarenes from [(18) F]fluoride for radiopharmaceutical discovery is reported. The method is practical, operationally simple, tolerates a wide scope of functional groups, and enables the labeling of a variety of arenes and heteroarenes with radiochemical yields (RCYs, not decay-corrected) from 10 to 60 %. The (18) F-fluorination precursors are readily prepared from aryl chlorides, bromides, iodides, and triflates. Seven (18) F-difluoromethylarene drug analogues and radiopharmaceuticals including Claritin, fluoxetine (Prozac), and [(18) F]DAA1106 were synthesized to show the potential of the method for applications in PET radiopharmaceutical design., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Here we describe a simple and sensitive analytical method for the enantioselective quantification of fluoxetine in mouse serum using ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry. The sample preparation method included a simple deproteinization with acetonitrile in 50 μL of serum, followed by derivatization of the extracts in 50 μL of 2 mM 1R-(-)-menthyl chloroformate at 45ºC for 55 min. These conditions were statistically optimized through response surface methodology using a central composite design. Under the optimized conditions, neither racemization nor kinetic resolution occurred. The derivatized diastereomers were readily resolved on a conventional sub-2 μm C18 column under a simple gradient elution of aqueous methanol containing 0.1% formic acid. The established method was validated and found to be linear, precise, and accurate over the concentration range of 5.0-1000.0 ng/mL for both R and S enantiomers (r(2) > 0.993). Stability tests of the prepared samples at three different concentration levels showed that the R- and S-fluoxetine derivatives were relatively stable for 48 h. No significant matrix effects were observed. Last, the developed method was successfully used for enantiomeric analysis of real serum samples collected at a number of time points from mice administered with racemic fluoxetine., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this work, a capillary electrophoretic methodology for the enantioselective in vitro evaluation of drugs metabolism is applied to the evaluation of fluoxetine (FLX) metabolism by cytochrome 2D6 (CYP2D6). This methodology comprises the in-capillary enzymatic reaction and the chiral separation of FLX and its major metabolite, norfluoxetine enantiomers employing highly sulfated β-CD and the partial filling technique. The methodology employed in this work is a fast way to obtain a first approach of the enantioselective in vitro metabolism of racemic drugs, with the additional advantage of an extremely low consumption of enzymes, CDs and all the reagents involved in the process. Michaelis-Menten kinetic parameters (Km and Vmax ) for the metabolism of FLX enantiomers by CYP2D6 have been estimated by nonlinear fitting of experimental data to the Michaelis-Menten equation. Km values have been found to be 30 ± 3 μM for S-FLX and 39 ± 5 μM for R-FLX. Vmax estimations were 28.6 ± 1.2 and 34 ± 2 pmol·min(-1) ·(pmol CYP)(-1) for S- and R-FLX, respectively. Similar results were obtained using a single enantiomer (R-FLX), indicating that the use of the racemate is a good option for obtaining enantioselective estimations. The results obtained show a slight enantioselectivity in favor of R-FLX., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An increasing number of quantitative bioanalyses need to be performed on samples available in limited volumes, such as pharmacokinetic studies on small animals. In this context, microfluidic systems as the LC-chip device coupled to a mass spectrometer combine small sample volume requirements and high sensitivity. In this study, we present the development of a microfluidics-based method for fluoxetine (FLX) and norfluoxetine (NFL) quantitation dedicated to pharmacokinetic investigations in the rat serum. Using the methodology of experimental design, LC parameters were optimised in terms of peak resolution, analysis time, and sensitivity. An SPE method was then developed for serum samples on miniaturised 96-well plates containing a mixed-mode strong cation exchanger that provided very clean extracts with good analyte recovery (≥66.0%). The total SPE-LC-MS/MS process required only 20 μL per sample and the method provided a good sensitivity in a total run time of 12 min. Finally, the developed method for FLX and NFL quantitation in rat serum was fully validated. After having selected the most appropriate regression model on the basis of the accuracy profiles, method selectivity, trueness, precision, accuracy and linearity were demonstrated., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Several pharmacokinetic processes are affected by enantioselectivity (ES). At the level of distribution, protein binding (PB) is one of the most important. The enantioselective binding of fluoxetine (FLX) to HSA has been evaluated in this work by ultrafiltration of FLX–HSA mixtures and chiral analysis of unbound fractions by EKC-CD. PB, affinity constants (K) and ES were obtained for both enantiomers of FLX. In order to improve the consistency of the estimations, the evaluation of affinity constants of each enantiomer was performed using two designs, one keeping constant the total concentration of protein and varying the total concentration of the enantiomers, and the other in the opposite way, in both cases via an unusual short-concentration interval strategy to assure model validity. Different mathematical approaches were compared and characterised and some of them, judged as the most consistent under the experimental conditions used, were selected to provide final estimates. Quality considerations include criteria for three critical aspects: (i) detecting/eliminating outliers, (ii) checking the number of binding sites in the protein and (iii) evaluating the robustness of each approach. The differences on estimates from the selected approaches were used as an uncertainty source to delimit the reported values. The ES of HSA for FLX enantiomers was approximate. Estimates include the assumptions of independent and competitive models. In the last case, a SIMPLEX function was designed capable of simultaneously optimizing the non-linear binding models for both enantiomers, thus improving the consistence of results.

A column switching LC method is presented for the analysis of fluoxetine (FLU) and norfluoxetine (NFLU) by direct injection of human plasma using a lab-made restricted access media (RAM) column. A RAM-BSA-octadecyl silica (C-18) column (40 mm x 4.6 mm, 10 microm) is evaluated in both backflush and foreflush elution modes and coupled with a C-18 lab-made (50 mm x 4.6 mm, 3 microm) analytical column in order to perform online sample preparation. Direct injection of 100 microL of plasma samples is possible with the developed approach. In addition, reduction of sample handling is obtained when compared with traditional liquid-liquid extraction (LLE) and SPE. The total analysis time is around 20 min. A LOQ of 15 ng/mL is achieved in a concentration range of 15-500 ng/mL, allowing the therapeutic drug monitoring of clinical samples. The precision values achieved are lower than 15% for all the evaluated points with adequate recovery and accuracy. Furthermore, no matrix interferences are found in the analysis and the proposed method shows to be an adequate alternative for analysis of FLU in plasma.

The enantiomeric separation of a series of imidazole analogues of Fluoxetine and Miconazole endowed with potent antifungal activity was performed using cellulose tris(4-methylbenzoate) (Chiralcel OJ) and cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD) as chiral stationary phases. Binary mixtures of n-hexane and alcohol as well as pure alcohols (ethanol or 2-propanol) were used as eluents. The enantiomer elution order was monitored by chiroptical detectors based on on-line optical rotation and circular dichroism measurements. For some of the compounds studied very high enantioseparation factor values (alpha > 7) on Chiralcel OJ CSP were observed. In order to study the chiroptical characteristics of the two most biologically active compounds, chromatographic resolutions were carried out on a semipreparative scale. Assignment of the absolute configuration was empirically established by comparing the CD spectra of the separated enantiomers with those obtained from the enantiomers of Miconazole.