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Keywords:

  • drug-drug interaction;
  • ethnic groups;
  • fesoterodine;
  • 5-HMT;
  • renal impairment

Abstract

This analysis was conducted to investigate factors that affect 5-hydroxymethyl tolterodine (5-HMT) pharmacokinetics after administration of fesoterodine sustained release tablets to Westerners and East Asians. Ten pharmacokinetic studies and three efficacy/safety studies in overactive bladder (OAB) patients were pooled for the population pharmacokinetic analysis. The plasma 5-HMT concentration data were described by a 1-compartment model with first order absorption and a lag time. Creatinine clearance (CLCR), hepatic impairment, CYP2D6 genotype, and concomitant medication with CYP3A inhibitor/inducer were identified as influential covariates. It was estimated that decreasing of CLCR from 80 to 15 mL/min resulted in a 39.5% reduction in 5-HMT apparent oral clearance (CL/F). Hepatic impairment, CYP2D6 poor metabolizer, and CYP3A inhibitor were estimated to reduce CL/F by about 60%, 40%, and 50%, respectively. CYP3A inducer resulted in about fourfold increase in CL/F. Although sex and Japanese ethnicity were selected as covariates on CL/F, each resulted in only about 10% decrease and increase of CL/F, respectively. Of the influential covariates of 5-HMT CL/F, CLCR, hepatic impairment, CYP2D6 genotype, and concomitant medication with CYP3A inhibitor/inducer were of significance, whereas sex and Japanese ethnicity covariates were considered not to have clinically significant impact on exposures of 5-HMT.