Rapid tandem mass spectrometric method for determination of gabapentin in human plasma

A rapid tandem mass spectrometric (MS-MS) method for the quantification of gabapentin (GBP) in human plasma using 4-phenyl-A-aminobutanoic acid as an internal standard (IS) has been developed and validated. The drug and the internal standard were analyzed, by flow injection analysis without chromatographic separation, using a mobile phase of acetonitrile-water-formic acid (50:50:0.025, v/v/v) at a flow rate of 0.1 mL min(-1). The run-cycle time was < 3 min injection-to injection. Quantitation was achieved using multiple reaction monitoring (MRM) scan at MRM transitions m/z 172 > 154 and m/z 180 > 117 for GBP and the IS, respectively. Ion suppression study indicated practically no suppressive effect of plasma constituents on the mass ions detection of GBP and IS, when measured in MRM scanning mode. Calibration curves were linear over the concentration range of 0.1-10 mu g mL(-1) (r > 0.999) with a limit of quantification of 0.1 mu g mL(-1) (RSD%; 7.6 and % DEVs; -3.0 to +17.0%). Validation data showed that the RSD% values were in the range of 1.85 to 13.06%, whereas, the % DEVs values ranged from -1.4 to +10.0% indicating good precision and accuracy. Analytical recoveries of GBP from spiked human plasma were in the range of 98.9 to 101.3%. On the other hand, recoveries of GBP from stored human plasma samples were in the range of 100.0 to 107.5% indicating that GBP was stable in plasma, with no appreciable degradation, when stored at -20 degrees C. The developed method was applied for GBP monitoring in plasma samples of patients treated with GBP.