Validation of the determination of oxymetholone in human plasma analysis using gas chromatography–mass spectrometry: Application to pharmacokinetic studies

A simple and rapid procedure for extraction of oxymetholone in human plasma using gas chromatography coupled with quadrupole mass spectrometric was evaluated. The method involves analyte extraction with tert.-butylmethylether after alkalinization of the plasma and derivatization with MSTFA–NH4I–2-mercaptoethanol before the high resolution gas chromatographic–mass spectrometry separation. Methyltestosterone was used as internal standard. The calibration curves were linear, with typical r2 values >0.995 and Ftable>Fcalculated (α=0.05). Recovery from plasma proved to be more than 70%. The method was accurate and reproducible, and was successfully applied to determine the pharmacokinetic parameters of oxymetholone for healthy volunteers after oral administration of 50 mg of the compound. The (Cmax) and (Tmax) were 18.8±0.4 ng/ml and 210±42.4 min, respectively.