Simultaneous Quantitative Determination of Bupropion and its Metabolites by High Performance Liquid Chromatography Tandem Mass Spectrometry Detection: Application to Bioequivalence Study

  Objective: A rapid, selective, sensitive, precise and accurate liquid chromatography in tandem with electro-spray ionization mass spectrometry method has been developed and validated for the simultaneous quantification of bupropion (BPR), hydroxyl bupropion (HBPR), erythrohydrobupropion (EHBPR) and threohydrobupropion (THBPR) in human plasma using only 100µL of human plasma sample. Methodology: Multi reaction monitoring detection was performed by electrospray ionization in the positive ion mode, conferring an additional selectivity to the method. The solid phase extraction technique was used for sample preparation. Chromatographic separation of drug and metabolites with better peak shape and resolution was achieved by using an Acquity BEH phenyl column with an isocratic elution of 42 % methanol and 58 % ammonia (0.06%, v/v) aqueous solution at a flow rate of 0.5 ml/min. Methanol was chosen because it enabled good resolution between THBPR and EHBPR as well as good peak symmetry of all the four analytes. Detection was carried out by mass spectrometry using positive electro-spray ionization mode, and the compounds were monitored using multiple reactions monitoring method. Deuterium-labeled isotopes of the compounds were used as internal standards. Results and Conclusion: No significant matrix effect was observed in the presented method. The assay method was validated over the concentration range of 1.75-500 ng/ml for BPR; 5-1000 ng/ml for HBPR; 0.5-100 ng/ml for EHBPR; and 2-500 ng/ml for THBPR as per FDA guideline and validated method was successfully applied for estimation of drug and metabolite concentration in the healthy adult volunteers, bioequivalence and pharmacokinetic study of Bupropion hydrochloride 300 mg extended release tablets under fasting condition.