Determination of leuprolide in beagle dogs' serum by high performance liquid chromatography-mass spectrometry and study on bioequivalence

Abstract

An HPLC-MS/MS method was used to calculate the pharmacokinetic parameters and to evaluate the bioequivalence versus equal dose of test or reference leuprolide microspheres in male healthy beagle dogs. The MS-MS detection was made by monitoring 605.5→221.3 (m/z) for leuprolide and 584.4→221.3 (m/z) for the I.S. The dynamic range was from 0.103-103 ng mL-1. The recovery rate was 78.75- 90.77 % and matrix effect was -5.25-10.3 %. The intra- and inter-assay precisions were with relative standard deviations (RSDs) of ≤ 5.19 % (n = 6) and ≤ 6.48 % (n = 6), respectively. Evaluation of bioequivalence was made by analysis of variance, Double-sided t-test and (1-2α) confidence interval method. The results show the test agents, the AUC0→t leuprolide 90 % confidence interval for the reference preparation of the corresponding parameters of 99.6-102.5 %, the AUC 0→¥ leuprolide 90 % confidence interval for the reference preparation of the corresponding parameters of 90.2-103.9 %, Cmax 90 % confidence interval for the reference preparation of the corresponding parameters of 91.0-129.8 %.