Background: A new LC-MS/MS method for the simultaneous determination of lamivudine, zidovudine, and nevirapine in human plasma is developed using column-coupling technique. Method: Labeled compound of respective analyte was used as an internal standard. After extraction from 100 μL plasma by solid phase extraction method, analytes were separated on a C18 column coupled with a cation exchange column. Total run time was 4.5 min. A tandem mass spectrometric detection was conducted using multiple reaction monitoring under positive ionization mode with an electrospray ionization interface. The method was validated as per the FDA guidelines over the concentration range of 9.47-1466.67 ng/mL for lamivudine, 10. 32-1600.00 ng/mL for zidovudine, and 15.05-2426.67 ng/mL for nevirapine. Results: Precision was in the range 0.86-5.77 (intraday) and 1.92-8.19 (interday) while accuracy was 93.25-104.36 % (intraday) and 96.83-103.28 % (interday). Stabilities of stock in aqueous solutions and in plasma were also determined. Conclusion: The method can be applied to the pharmacokinetic study of a combination treatment.

No abstract

No abstract

A LCMS/MS method for the simultaneous determination of ampicillin and sulbactam in human plasma was described. After protein precipitation using 2mL of acetonitrile, 250µL of supernatant was mixed with 1.000 mL of 0.1% Acetic Acid in Milli-Q-water. 10µL was injected to a Biobasic AX column and eluted with 10mM Ammonium acetate and Acetonitrile: 60:40, v/v at a flow rate of 0.5mL/min. MRM transitions were monitored in negative mode as m/z 348.1 → 206.8 (AMP), 231.9 → 187.8 (SUL) and m/z 353.0 → 211.9 (AMP D5). Sample concentrations were calculated by linear regression analysis using the analyst software1.6.3. An excellent linear response was obtained over the concentration ranges 0.1040µg/mL to 10.1562µg/mL for Ampicillin and 0.0510µg/mL to 6.1552µg/mL for Sulbactam. The intra-day and inter-day precision were within 3.50% for all analytes. The assay accuracy was 96.27 –103.59 %. Mean recoveries were 84.51% and 98.54% for ampicillin and sulbactam, respectively. The limits of detections were 0.026µg/mL and 0.013µg/mL for ampicillin and sulbactam. This method was successfully used for a bioequivalence study.