Reversed-phase-HPLC enantioseparation and control of enantiomeric purity of duloxetine using a new chiral reagent and recovery of enantiomers.

This study reports a rapid and low-cost LC method for control of enantiomeric purity of duloxetine. Though duloxetine, as marketed and administered, is expected to be a single (S)-enantiomer, the analysis of a few commercial branded samples by the method developed and presented here showed that they contain a relatively high percentage of (R)-enantiomer (e.g., 2.71-5.42%, which is undesirable in drug formulations). A new chiral derivatizing reagent [isatinyl-(S)-naproxen amide] was synthesized on (S)-naproxen platform. Diastereomeric derivatives were synthesized under microwave irradiation and were separated using reversed-phase-HPLC on a C18 column. A combination of acetonitrile and triethylammonium phosphate buffer (9 mM, pH 4) as the mobile phase and detection at 273 nm were found successful. The diastereomeric derivatives at preparative scale were separated using open column chromatography, and the native enantiomers were obtained and characterized. The HPLC separation method was validated for detection limit, linearity, accuracy, and precision. The limits of detection of (S,R)-diastereomer and (S,S)-diastereomer were found to be 12 and 16 pg/mL, respectively, for the 20-µL injected volume. The method so developed has a practical significance and greater societal impact in establishing the control of enantiomeric purity and in ensuring the enantiomeric purity of the drug meant for human consumption.

Achiral and chiral analysis of duloxetine by chromatographic and electrophoretic methods, a review on the separation methodologies.

Duloxetine (DLX) is a widely used antidepressant drug belonging to the class of selective serotonin and norepinephrine reuptake inhibitors (SNRIs); its efficacy has been demonstrated in the treatment of not only major depressive disorders but also diabetic neuropathic pain, generalized anxiety disorder, fibromyalgia or stress urinary incontinence. It is a chiral substance and is used in therapy in the form of the enantiopure S-DLX, which is twice as active as R-DLX. Several methods have been published for the achiral and chiral determination of DLX in pharmaceuticals, biological materials and environmental samples, the majority using liquid chromatography and capillary electrophoresis coupled with different detection techniques (UV detection, fluorescence, mass spectrometry). The aim of the current review is to provide a systematic survey of the analytical techniques used for the determination of DLX from different matrices.

Analysis of neurotransmitters in Daphnia magna affected by neuroactive pharmaceuticals using liquid chromatography-high resolution mass spectrometry.

Neurotransmission plays an essential role during the central nervous system (CNS) development. During the last years, several studies based on the changes produced in neurotransmitters of aquatic organisms caused by pharmaceuticals have been reported. Daphnia magna, the aquatic ecotoxicological model organism, shares several of the neurotransmitters targeted by antidepressant and other neuro-active drugs with vertebrates. Therefore, a method based on liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) has been applied for the first time to study the levels of 41 neurotransmitters in Daphnia magna under the effect of four different neuro-active pharmaceuticals (sertraline, venlafaxine, duloxetine and fluoxetine). In addition, the performance of LC-HRMS was studied in terms of linearity, sensitivity, intra- and inter-day precision, and overall robustness. The developed analytical method using LC-HRMS is a new tool for neurotoxicology research using the Daphnia magna model. As a result, general differences on the concentrations of those neurotransmitters exposed to the mentioned pharmaceuticals were observed.

Degradation of duloxetine: Identification of transformation products by UHPLC-ESI(+)-HRMS/MS, in silico toxicity and wastewater analysis.

Duloxetine (DUL), an antidepressant drug, has been detected in surface water and wastewater effluents, however, there is little information on the formation of its transformation products (TPs). In this work, hydrolysis, photodegradation (UV irradiation) and chlorination experiments were performed on spiked distillated water, under controlled experimental conditions to simulate abiotic processes that can occur in the environment and wastewater treatment plants (WWTPs). Eleven TPs, nine from reaction with UV light and two from chlorine contact, were formed and detected by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, and nine of them had their chemical structures elucidated upon analyses of their fragmentation patterns in MS/MS spectra. The formation and degradation of the TPs were observed. The parent compound was completely degraded after 30 min in photodegradation and after 24 hr in chlorination. Almost all TPs were completely degraded in the experiments. The ecotoxicity and mutagenicity of the TPs were predicted based on several in silico models and it was found that a few of these products presented more ecotoxicity than DUL itself and six TPs showed positive mutagenicity. Finally, wastewater samples were analyzed and DUL and one TP, possibly formed by chlorination process, were detected in the effluent, which showed that WWTP not only did not remove DUL, but also formed a TP.

Development and validation of a method for analysing of duloxetine, venlafaxine and amitriptyline in human bone.

A method based on gas chromatography-mass spectrometry (GC-MS) is described for the determination of venlafaxine, amitriptyline and duloxetine in human bone. Pulverized samples were incubated in methanol for 1 h under ultrasonication, after the addition of sertraline as internal standard. The samples were centrifuged, and the supernatants were evaporated. Samples were then resuspended in 0.1 M phosphate buffer pH 6 and subjected to solid phase extraction. Chromatography was performed on a fused silica capillary column and analytes were determined in the selected-ion-monitoring (SIM) mode. The assay was validated in the range 0.3-1 ng/mg (depending on the drug) to 500 ng/mg. The mean absolute recoveries ranged from 92.6% to 96.2%, the matrix effect from 76.9% to 103.3% and process efficiency from 74% to 95.9% depending on the analyte. The intra- and inter-assay accuracy values were always better than 20%. The validated method was then successfully applied to real bone samples from forensic cases in which toxicological analysis for these drugs in blood had been positive. Drugs were detected in bone in all blood positive results, the approximate concentrations being 36.4 ng/mg for amitriptyline, 19.3-3 ng/mg for duloxetine and 4.6-2 ng/mg for venlafaxine.

Fatal overdose with a combination of SNRIs venlafaxine and duloxetine.

Drugs for the treatment of depressive disorders, including SNRIs (serotonin noradrenaline reuptake inhibitors) venlafaxine and duloxetine, are widely prescribed as they have a high therapeutic to toxicity ratio. In rare cases, adverse effects may be severe, usually due to iatrogenic, accidental or intentional self-overdose that cause the excessive accumulation of serotonin and noradrenaline in synaptic clefts. Lethal intoxication with a combination of venlafaxine and duloxetine (postmortem blood concentrations 24 mg/L and 0.97 mg/L, respectively) without co-ingested substances, comorbidities or injuries that could have an unknown contribution to a fatal outcome is presented for the first time in the following case report, with a comprehensive clinical history, and complete results of the performed analyses. The cause of death was a serotonin syndrome that progressed to death in approximately six hours and 15 min after the suicidal ingestion of venlafaxine and duloxetine. Despite the high therapeutic to toxicity ratio SNRIs, which are reserved for patients with severe forms of depressive disorders and a higher suicidal tendency, they should be cautiously prescribed and handed over in smaller packages to make them easier to follow, and thus avoid accumulation within the patient's reach.

Investigation of dextrin-based synergistic system with chiral ionic liquids as additives for enantiomeric separation in capillary electrophoresis.

In this paper, two spiral structure CILs, 1-butyl-3-methylimidazolium(T-4)-bis[(2S)-2-(hydroxy-κO)-3-methyl-butanoato-κO]borate(BMIm+BLHvB-) and 1-butyl-3-methylimidazolium (T-4)-bis[(αS)-α-(hydroxy-κO)-4-methyl-benzeneacetato-κO]borate (BMIm+BSMB-)were applied to evaluate their potential synergistic effect with dextrin for CE enantiomeric separation. The established dextrin-based synergistic system with CILs as additives showed good separation performance towards four tested drugs, including duloxetine, ketoconazole, sulconazole and citalopram. It was also observed that significantly improved separation and selectivity for tested analytes were achieved in CILs/dextrin synergistic system compared to single dextrin system. Primary parameters, such as the concentration of CIL, dextrin concentration, buffer pH and applied voltage, were systematically investigated to optimize the enantiomeric separation with BMIm+BLHvB-/dextrin as model system. Finally, the method of Statistical Product and Service Solutions (SPSS) was exploited to further elucidate the influence of experimental parameters on the synergistic effect.

Ultrasonic assisted magnetic dispersive solid phase microextraction for pre concentration of serotonin-norepinephrine reuptake inhibitor drugs.

A simple and sensitive ultrasonic assisted magnetic dispersive solid phase microextraction method (UAMDSPME) coupled with high performance liquid chromatography was developed to determine serotonin-norepinephrine reuptake inhibitor drugs including duloxetine (DUL), venlafaxine (VEN) and atomoxetine (ATO) in human urine, river water and well water samples. A novel and efficient SPME sorbent, magnetic p-Phenylenediamine functionalized reduced graphene oxide Quantum Dots@ Ni nanocomposites (MrGOQDs-PD@ Ni), was prepared and applied for extraction of the analytes. Several effective parameters on the extraction efficiency of the analytes were investigated and optimized with experimental design approach. The performance of MrGOQDs-PD@ Ni as the SPME sorbent for the extraction of DUL, VEN and ATO was then compared with magnetic graphene oxide (MGO@Fe3O4) and magnetic reduced graphene oxide (MrGO@ Ni). Under the optimized conditions for the MrGOQDs-PD@ Ni sorbent, the intra-day relative standard deviations (RSDs, n = 5) and the limits of detections (LODs) were lower than 4.6% and 1.1 ngmL-1, respectively. Moreover, the good linear ranges were observed in wide concentration ranges with R-squared larger than 0.9878. Finally, the enrichment factors in the range of 137-183 and the recovery percentage in the range of 89.2-94.8% were obtained to determine the analytes in the real samples.

Comprehensive Duloxetine Analysis in a Fatal Overdose.

Duloxetine is a second-generation selective serotonin and norepinephrine reuptake inhibitor used primarily for the treatment of depression. Relatively few fatalities have been reported in association with its use. Similarly, there are no known reports that provide a comprehensive analysis of blood, fluid and tissue samples in an overdose setting. Herein we present a fatal case of duloxetine toxicity with both the highest reported post-mortem blood concentration and a comprehensive toxicological analysis of duloxetine in femoral blood, vitreous humor, liver tissue, urine and gastric contents. In doing so, we hope to provide data that can assist both toxicologists and forensic pathologists with assessing duloxetine toxicity in the future.

Development of sensitive spectrofluorimetric and spectrophotometric methods for the determination of duloxetine in capsule and spiked human plasma.

A new, sensitive and selective spectrofluorimetric method has been developed for the determination of duloxetine (DLX) in capsule and spiked human plasma. DLX, as a secondary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl), a highly sensitive fluorogenic and chromogenic reagent used in many investigations. The method is based on the reaction between the drug and NBD-Cl in borate buffer at pH 8.5 to yield a highly fluorescent derivative that is measured at 523 nm after excitation at 478 nm. The fluorescence intensity was directly proportional to the concentration over the range 50-250 ng/mL. The reaction product was also measured spectrophotometrically. The relation between the absorbance at 478 nm and the concentration is rectilinear over the range 1.0-12.0 µg/mL. The methods were successfully applied for the determination of this drug in pharmaceutical dosage form. The spectrofluorimetric method was also successfully applied to the determination of duloxetine in spiked human plasma. The suggested procedures could be used for the determination of DLX in pure form, capsules and human plasma being sensitive, simple and selective.