Determination of simvastatin in human plasma by UFLC-MS/MS and its application to bioequivalence study / 中国药学杂志

ABSTRACT

OBJECTIVE: To develop a UFLC-MS/MS method for the determination of simvastatin in human plasma, so as to investigate the relative bioavailability of two kinds of simvastatin tablets. METHODS: After liquid-liquid extraction by methyl tert-butyl ether, the analytes were seperated on a Shim-pack XR-ODS column with a gradient elution by the mobile phase of water (A) and aceto-nitrile (B). Conditions of the gradient elution were as follows 0.01-3 min, B80%-90%; 3-3.5 min, B90%-95%, 3.51-5 min, B80%. Multiple reaction monitor (MRM) was used to determine the concentration of simvastatin (m/z 441.2 → 325.1) and the internal standard, lovastatin (m/z 427.2 → 325.2). A single oral dose of 40 mg test or reference preparation was given to 20 healthy volunteers in a randomized crossover design. Blood samples were obtained and analyzed by the validated UFLC-MS/MS method, and the pharmacokinetics and bioavailability were evaluated by Phoenix WinNonlin 6.0 software. RESULTS: The calibration curve of simvastatin was linear over 0.1-20 ng · mL-1 (r=0.9954) with the lower limit of quantity of 0.1 ng · mL-1. The absolute recoveries were between 63.9% and 83.8%, the extraction recoveries were 63.9%-83.8%, and inter- and intra-day RSDs were less than 7.1% and 10.0%, respectively. The main pharmacokinetic parameters of simvastatin of the test and reference tablets were as follows t1/2 were (3.96 ± 1.65) and (3.77 ± 1.75)h; ρmax were (8.3641 ±4.9898) and (8.4399 ± 4.8566) ng · mL-1; tmax were (1.71 ± 1.19) and (174 ± 1.10) h; AUC0-t were (29.74 ± 13.05) and (31.16 ± 13.92) ng · h · mL-1; AUC0-∞ were (32.35 ±14.56) and (33.39 ± 14.55)ng · h · mL-1, respectively. The relative bioavailability of the test to reference tablets was (97.3 ± 24.3)%. CONCLUSION: The two preparations are bioequivalent. The established method is successfully used for the bioequivalence study of simvastatin preparations.