Sensitive and Selective Reversed-Phase High Performance Liquid Chromatographic-UV Spectrophotometric Determination of Dextromethorphan and its CYP2D6 Mediated Metabolite, Dextrorphan in Human Urine

Purpose: To develop a simple, sensitive and selective method for the determination of dextromethorphan and its metabolite, dextrophan in human urine using reversed-phase high performance liquid chromatography with UV-spectrophotometric detection (RP-HPLC-UV).Methods: Pre-column sample clean-up was carried out by liquid-liquid extraction of the analytes with chloroform: isopropanol (70:30) solution after alkalization of 1000 μL sample and spiking of internal standard, morphine. The samples were chromatographed in a reversed-phase (C-18) ultra sphere silica (5μm particle size and 250 x 4.6 mm I.D). The mobile phase consisted of methanol: acetonitrile: 0.5% w/v ammonium acetate (10:10:80) adjusted to pH 2.8 with orthophosphoric acid and pumped through the column at 1ml/min flow rate. The analytical method was validated for accuracy and precision as well as the recovery of the analytes, dextromethorphan and its metabolite, dextrophan over the concentration range of 0.20 to 5.0μg/ml.Results: The standard curves were linear over the concentration range of 0.2 to 5.0μg/ml for dextromethorphan and dextrorphan. The regression coefficients (R2) of the analytes were >0.99. The method was reproducible with coefficient of variation for the analytes being < 10 %. Dextromethorphan was well resolved from its metabolite, dextrorphan and the internal standard, morphine. The limits of detection of dextromethorphan and dextrorphan were 50ng/ml and the recoveries and accuracies were greater than 85 and 90 %, respectively.Conclusion: The analytical assay method exhibits good precision and selectivity and it was applied to the analysis of dextromethorphan and dextrorphan in urine for the assessment of CYP2D6 activity.Keywords: Dextromethorphan, Dextrophan, Reversed-phase high performance liquid chromatography, CYP2D6 activity, Human urin

Rapid high performance liquid chromatographic determination of chlorpropamide in human plasma

Samples were extracted with dichloromethane and the organic layer evaporated to dryness. The residue was dissolved in methanol, and 25 ìl aliquot injected onto the column. Tolbutamide was used as theinternal standard for chlorpropamide. The UV detector response was linear over the range 0 – 300 ìg/ml, with a correlation coefficient of 0.999 and detection limit of 1.30 ng/ml. Within day and betweenday assay variations was generally < 2.50%. No interference from endogenous constituent wasobserved. The utility of the method was demonstrated by determine chlorpropamide in samples from human volunteers following a single oral dose of 250 mg in drug interaction studies. The procedure issimple and fast, requiring small volumes of plasma

Physicochemical Analysis of the Aqueous Extracts of Six Nigerian Medicinal Plants

Purpose: Extracts of Picralima nitida seeds, Detarium microcarpum stem bark, Aframomum melagueta seeds, Terminalia catappa leaves, Acacia nilotica pods, and Morinda lucida stem bark, are under consideration for development into suitable dosage forms for treating diabetes mellitus, sickle cell anemia and malaria. This study aimed at evaluating the extracts for features that would influence decisions on them in the course of the project.Methods: Physicochemical determinations, including proximate analysis, were done by sensory examination, and gravimetric and electrochemical techniques. Thin layer chromatography was carried out with normal silica plates using various solvent systems. Metallic content analyses were carried out by atomic absorption spectroscopy.Results: The extracts were dry but hygroscopic, with a loss on drying range of 0.26 – 12.00 %w/w. The pH of the 5 - 10 % solutions ranged 5 - 7. No harsh sensory effects, such as lacrimation, were detected in any of the extracts. Total ash ranged from 3.79 – 20.68 %w/w, while acid insoluble ash values were below detection. The extracts yielded reproducible chromatograms on normal silica plates developed with various solvent systems. Copper, present at 0.16 - 0.58 mg/100g, was the lowest occurring microelement while calcium content was highest, at 41 - 216 mg/100g. The level of lead, a heavy metal, was 0.05 - 0.22 mg/100g.Conclusion: The results confirm that the extracts require no special handling, possess characteristics that would allow their possible development into solid dosage forms, and that their lead contentscomplied with official limits.Keywords: Aqueous extract, Picralima nitida, Detarium microcarpum, Aframomum melagueta, Terminalia catappa, Acacia nilotica, Morinda lucida