臨床薬理学および生物薬剤学

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Determination of Ethambutol in Presence of Fixed Dose Combination Molecules from Human Plasma by Direct Injection to Liquid Chromatography Tandem Mass Spectrometry

Chaitanya Krishna A, Saravanan RS, Sathiyaraj M, Jeevanantham S and Baskaran R

A simple, rapid, specific and sensitive liquid chromatography tandem mass spectrometric method has been developed and validated for the estimation of Ethambutol from 100 μL of human plasma. Ethambutol is extracted from human plasma by Protein Precipitation Extraction. Glipizide was used as an internal standard. Detection was performed using TSQ Quantum Discovery max mass spectrometer with ESI source in positive polarity. The detection transition for Ethambutol is 205.230 → 116.090 and for Glipizide is 446.200 → 321.200. Chromatographic separation of analyte and internal standard were carried out using a reverse phase Agilent, Eclipse XDB-C18, 4.6 X 150 mm, 5 μ at a flow rate of 0.500 mL/min. The mobile phase is composed of methanol: 0.1 %TFA in 5 mM Ammonium Acetate (90:10) v/v. The assay of Ethambutol is linear over the range of 0.106 μg /mL to 7.006 μg/mL with a precision < 9.91% and the limit of quantification in plasma for Ethambutol was 0.106 μg/mL. Mean extraction recovery obtained was 98.70%. Samples are stable at room temperature for 6 hrs, processed samples were stable at least for 28 hrs and also stable at three freeze–thaw cycles. The method has been used to perform pharmacokinetic and bioequivalence studies in humans.