Aims: To characterize the pharmacokinetic, pharmacodynamic and safety profiles of donepezil in subjects with moderate renal impairment and matched healthy controls during single-dose and multiple-dose phases.
Methods: This open-label study enrolled subjects with moderate renal impairment (creatinine clearance [CL(Cr)] 17-33 ml min(-1) 1.73 m(-2) body surface area) and age, weight and sex-matched healthy controls. A single-dose (5 mg donepezil) phase was followed by a 23-day multiple dose (5 mg day(-1) donepezil) steady-state phase. The pharmacokinetic and pharmacodynamic parameters of donepezil were determined for up to 144 h after the first dose and 168 h after the last dose.
Results: Thirty-six subjects were enrolled, 19 renally impaired and 17 healthy controls. All pharmacokinetic and pharmacodynamic parameters were similar between groups after a single dose of donepezil (C(max) 5.17 +/- 0.36 and 6.07 +/- 0.49 ng ml(-1); AUC(0-24) 76.05 +/- 5.54 and 77.45 +/- 4.49 ng.h ml(-1); mean maximum percentage inhibition [I(max)] red blood cell (RBC) AChE activity 32.07 +/- 2.00 and 31.69 +/- 2.45%; for subjects with renal impairment and healthy subjects, respectively). Pharmacokinetic parameters under steady-state conditions did not differ between renally impaired and healthy subjects (C(SS) 20.83 +/- 1.78 and 18.38 +/- 1.52 ng ml(-1); AUC(0-24) 500.0 +/- 42.8 and 441.1 +/- 36.4 ng.h ml(-1); degree of accumulation [R(A)] 6.98 +/- 0.59 and 5.94 +/- 0.53; for subjects with renal impairment and healthy subjects, respectively). Main pharmacodynamic parameters were also similar in renally impaired and healthy subjects at steady state (average percentage inhibition [I(SS)] RBC AChE activity 65.11 +/- 2.52 and 60.62 +/- 2.95, respectively). Protein binding was also similar between groups (% free donepezil 23.54 +/- 1.96 and 20.23 +/- 0.64, respectively). Donepezil was well tolerated by both groups.
Conclusions: These results indicate that the pharmacokinetics of donepezil are not altered after dosing to steady state, and that donepezil can be administered safely to subjects with moderate renal impairment.