Effect of the CYP2C9*3 allele on lornoxicam metabolism

Abstract

Background: We investigated whether the CYP2C9 genotypes would affect lornoxicam metabolism in healthy volunteers.

Methods: Twelve healthy volunteers who had been genotyped for CYP2C9 gene were selected to participate in our study. After 8 mg lornoxicam was taken, blood samples were drawn from 0 to 36 h. The plasma concentrations of lornoxicam and 5'-hydroxylornoxicam were determined by HPLC method. 5'-hydroxylornoxicam was purified from rabbits'urine by semi-preparative HPLC.

Results: Lornoxicam and 5'-hydroxylornoxicam both exhibit CYP2C9 genotype-dependent pharmacokinetic profiles. The area under the plasma concentration-time curve (AUC) of lornoxicam increased by 60 +/- 9.78% (P <0.05) and the AUC of 5'-hydroxylornoxicam decreased by 65 +/- 11.75% (p <0.001) in heterozygous CYP2C9*1/*3 subjects (n=6) compared with CYP2C9*1/*1 group (n=6). t1/2 value of lornoxicam and 5'-hydroxylornoxicam prolonged by 39 +/- 8.35% and curtailed by 59 +/- 6.83% respectively in CYP2C9*1/*3 subjects. But no significant differences in Tmax of lornoxicam and 5'-hydroxylornoxicam were observed between these 2 genotypes. In addition, for the first time we exploit the purification method for 5'-hydroxylornoxicam from rabbits' urine.

Conclusion: The CYP2C9*3 allele significantly affected the metabolism of lornoxicam. The pharmacokinetic parameters of both lornoxicam and 5'-hydroxylornoxicam were significantly different between these 2 genotypes.