Determination of plasma and brain levels of isotretinoin in mice following single oral dose by high-performance liquid chromatography

Bioanalysis of Endogenous Isotretinoin in Altered and Unaltered Human Plasma by Liquid Chromatography-Tandem Mass Spectrometry Coupled with Electrospray Ionization

Bioanalytical method development and validation of endogenous Isotretinoin with Isotretinoin D5 as internal standard was done as per current regulatory guidelines. The method is simple, rugged and sensitive enough to estimate endogenous Isotretinoin using the chromatography-tandem mass spectrometry technique. An alternative approach has been adopted for quantitative analysis of endogenous Isotretinoin in human plasma. Isotretinoin free matrix (surrogate matrix) was prepared and further used for the development and validation of Isotretinoin. The method was validated in altered and unaltered plasma. The chromatographic optimization was done with column (ACE C18, 100 × 4.6 mm I.D. 5 μm particle size), using a mobile phase containing 1 mM ammonium acetate, pH 3.0 as a solvent A and solvent B (1 mM ammonium acetate (pH 3.0) with acetonitrile in a ratio of 10:90). A flow rate was set at 0.75 mL/min in a binary gradient mode. The analyte was recovered by liquid-liquid extraction method with diethyl ether as an extraction solvent. Multi-reaction monitoring mode in negative polarity was implemented for the quantification of endogenous Isotretinoin in plasma. The calibration curve of Isotretinoin was linear (r2 > 0.9992) over the concentration range of 0.5-1000 ng/mL. The intra-day precision was found in a range of 2.0-3.9% CV for altered samples and 0.9-3.7% CV for unaltered samples. The inter-day precision was found 2.6-6.1% CV for altered samples and 1.3-3.8% CV for unaltered samples. The average recovery of the extraction procedure was found 64.6% for altered samples and 62.2% for unaltered samples.

Evaluation of uptake of the cytostatic methotrexate in Elliptio complanata mussels by LC-MS/MS

Aquatic organisms are continuously exposed to emerging contaminants coming from urban effluents of wastewater treatment plants. The contamination of surface water by those effluents poses a number of environmental risks, and pharmaceuticals are part of this class of effluent contaminants. Various classes of pharmaceuticals are not treated by wastewater treatment plants and anticancer drugs are part of them. The chemotherapy drug methotrexate (MTX) is an emerging contaminant and its growing use with the increase in cancer cases worldwide raises potential risk to aquatic organisms exposed to effluent discharges. However, chemical analyses in exposed freshwater aquatic organisms for ecotoxicological studies are rarely available and no studies have been done yet to accompany ecotoxicological data of exposed filter-feeding organisms. The purpose of this study was to develop a specific and sensitive analytical LC-MS/MS method for the quantification of methotrexate uptake in mussels exposed at different concentrations of the drug. A solid/liquid extraction followed by solid phase extraction (SPE) using an MCX phase purification scheme was optimized. The optimal recovery of 65% and matrix effect of 38% allowed to achieve a limit of quantification of 0.25 ng g-1, with an accuracy of 99-106%, a precision of no more than 3% RSD, and linearity ranging from 0.25 to 25 ng g-1. This methodology was tested with mussels exposed for 96 h at different concentrations (4 to 100 µg L-1) of MTX. The data revealed tissue uptake at concentrations ranging from 0 to 2.53 ng g-1. This suggests that this drug has low uptake potential and this methodology could be used to examine tissue levels of this drug in organisms continuously exposed to urban pollution.