[Pharmacokinetics and bioequivalence of eperisone hydrochloride tablet in healthy subjects].

Aim: To develop a HPLC-ESI-MS assay for determination of eperisone hydrochloride in human plasma and investigate the pharmacokinetics and bioequivalence of two eperisone hydrochloride tablets in human.

Methods: Buflomedil hydrochloride was used as the internal standard. After alkalized with saturated sodium bicarbonate solution, plasma was extracted with diethylether-cyclohexane (1:1) and separated using HPLC on a reversed-phase C18 column with a mobile phase of 10 mmol x L(-1) ammonium acetate buffer solution (adjusted to pH 3.88 with acetic acid)-methanol (20:80). HPLC-ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 260 for eperisone and m/z 308 for the internal standard. A randomized crossover design was performed in 20 healthy volunteers. In the two study periods, a single 100 mg dose of each tablet was administered to each volunteer.

Results: Calibration curve was linear over the range of 0.02-20 microg x L(-1). The limit of quantification for eperisone hydrochloride in plasma was 0.02 microg x L(-1). The main pharmacokinetics parameters T1/2, Tmax and Cmax were (2.7 +/- 0.4) h, (1.1 +/- 0.5) h and (2.8 +/- 2.8) microg x L(-1) for the reference tablet; (2.8 +/- 0.5) h, (1.1 +/- 0.4) h and (3 +/- 4) microg x L(-1) for the test tablet, respectively. The relative bioavalability of the test tablet was (101 +/- 13)%.

Conclusion: The assay was proved to be sensitive, accurate and convenient. The two formulations were bioequivalent.