Simple and rapid method determination for metformin in human plasma using high performance liquid chromatography tandem mass spectrometry: application to pharmacokinetic studies.

A rapid and simple method for quantitation of metformin (MET) in human plasma by HPLC-MS/MS was developed and validated. The sample preparation consists of plasma deproteinization using acetonitrile. The mobile phase consisted of water-acetonitrile and formic acid (55/45/0.048, v/v/%) and the run time was 3 min. A pursuit C(18) (100 mm x 2.0 mm i.d., 3 microm) column connected to a guard column MS-pursuit (0.20 mm x 0.20 mm i.d., 5 microm) was used. The range of the calibration curve was from 20 to 5000 ng/mL, the limit of quantitation being 20 ng/mL. The detection was performed on a mass spectrometer (ESI+), using metoprolol as internal standard. The calibration curves have r(2) values of 0.995 (CV=0.24%, n=10). The accuracy and precision were between 90.74 and 106.7% and coefficients of variations (CV) of 1.10 and 4.35%, respectively. The method was applied to determine the pharmacokinetic parameters: C(max) (1667.25 ng/mL) and T(max) (3.89 h).

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-NH(4)I-2-mercaptoethanol before the high resolution gas chromatographic-mass spectrometry separation. Methyltestosterone was used as internal standard. The calibration curves were linear, with typical r(2) values >0.995 and F(table)>F(calculated) (alpha=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 (C(max)) and (T(max)) were 18.8 +/- 0.4 ng/ml and 210 +/- 42.4 min, respectively.