Pharmacokinetics and bioequivalence of methylphenidate hydrochloride sustained-release micropellet capsules in rabbits

Abstract

Objective: To study the pharmacokinetics and bioequivalence of self-prepared methylphenidate hydrochloride(MPH) sustained-release micropellet capsules.Methods: Eight rabbits were given a single oral dose of 18 mg of MPH sustained-release micropellet capsules(test preparation) and MPH controlled-release tablets on the market(reference preparation) in a crossover study.LC/MS/MS method was employed to determine the plasma concentrations of MPH before and 0.5,1,2,3,4,6,8,10,12,24 and 32 h after administration of the medicine.The pharmacokinetic parameters were calculated and statistically analyzed.Results: The detection limit of MPH was 0.06 ng/ml.The plasma concentration curves of both the sustained-release micropellet capsules and the controlled-release tablets had two peaks.The main pharmacokinetic parameters of test preparation were as follows:tmax1=(1.02±0.04) h,tmax2=(5.98±0.03) h,cmax1=(0.82±0.22) ng/ml,cmax2=(1.54±0.33) ng/ml and those of reference preparation were as follows:tmax1=(0.50±0.02) h,tmax2=(3.96±0.03) h,cmax1=(0.45±0.12) ng/ml,cmax2=(1.25±0.29) ng/ml,respectively.The cmax and tmax of both peaks of the test preparation were higher or longer than those of the reference preparation.Conclusion: Compared with the controlled release tablets,the self-prepared MPH sustained-release micropellet capsules have better bioavailability.