Stability indicating LC-MS/MS method for estimation of Bromocriptine mesylate in human plasma application to a bioequivalence study

Narendra Kumar Reddy Kolli*, Swetha Polagani, Pamu Indira
Sri Vani School of Pharmacy, Chevuturu, Vijayawada, AP, India.

A B S T R A C T
Background: Sensitive and selective analytical method is required for the estimation of Bromocriptine in human plasma as Bromocriptine has been reported to have high intra-subject variability and is converted to its active metabolite Bromocriptine mesylate in in-vitro system and vice versa. If this inter conversion is not restricted, it could lead to pseudo estimation of Bromocriptine in human plasma. Methods: Aspecific, sensitive and reproducible high-performance liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for determination of Bromocriptine in human plasma, using Quetiapineas an internal standard. Bromocriptine and Quetiapine were extracted from human plasma using solid phase extraction, separated on Luna C18 (2) 100A (100×4.6mm, 5μm) column with mobile phase consisting of acetonitrile and 2mM ammonium acetate buffer (pH3.6) in the ratio of 90:10, v/v. Quantification was achieved by monitoring transitions of m/z 422.1 → 285.4 for Bromocriptine and 425.4 → 285.4 for Quetiapine in multiple reaction monitoring, using turbo ion source in positive polarity. Results: No matrix effect was observed within the linearity range of 0.121–35.637ng/mL (r>0.99).The degree of matrix effect for lovastatin was determined as 2.74%, and it had no impact on incurred samples analysis with runtime of 4.5min. The intra-and inter-day precision values were within11.38and8.62 %respectively, for lovastatin at the lower limit of quantification level. Conclusions: Stability data indicated that Bromocriptine is stable under various handling conditions & within significant inter-conversion between Bromocriptine and Bromocriptine mesylate. The method was successfully applied for the bioequivalence study of Bromocriptine after oral administration of 20mg tablet in healthy volunteer.
Keywords: Liquid chromatography-mass spectrometry, Bromocriptinemesylate, Quetiapine Hemi fumarate Inter-conversion.