Abstract:

Mefunidone (MFD), a pirfenidone analogue, has been suggested as a novel anti-fibrotic agent in preclinical research stage. In this work, we developed a sensitive and specified HPLC-UV method and validated it for the determination of MFD in rat plasma. A cost-effective protein precipitation method using methanol was used to process the plasma samples, and pirfenidone was employed as the internal standard (IS). Chromatographic separation was performed on an Agilent ZORBAX SB-Aq column (4.6 mm×250 mm, 5 μm) with a mobile phase consisting of 10 mM ammonium formate solution (pH 3.0, adjusted by 1.5‰ formic acid)–acetonitrile–methanol (60:23:17, v/v/v) at a flow rate of 1.0 mL/min, and the samples were monitored at an ultraviolet wavelength of 245 nm. The retention times of MFD and IS were 5.5 and 7.8 min, respectively. The calibration curve was linear (r² = 0.9997) between 0.1 and 20 μg/mL. The intra- and inter-day precisions were within 8.6%, and the bias of intra- and inter-accuracies of the method was between –4.2% and 6.5%. The method was successfully applied to pharmacokinetic study of MFD after i.g. and i.v. administration in rats. The elimination half-life was (3.41±0.81) h for i.g. administration and (2.26±0.87) h for i.v. administration. The absolute bioavailability of MFD in rat was 79.1%.  

Key words: Mefunidone, Anti-fibrotic, HPLC-UV, Pharmacokinetics, Bioavailability