Two open-label studies assessed the effects of hepatic and renal impairment on anidulafungin pharmacokinetics. A single 50-mg dose was administered intravenously to subjects with varying degrees of hepatic or renal insufficiency or with end-stage renal disease; all were matched to normal healthy controls. Anidulafungin was well tolerated. AUC, CL, C(max), t(max), t(1/2), and V(ss) between renally impaired subjects and controls were not significantly different (P>.05), and no measurable amounts of drug were found in dialysate. The same pharmacokinetic parameters were also not affected (P>.05) by mild or moderate hepatic insufficiency, with respective mean AUCs of 50.6 +/- 11.7 microg x h/mL and 68.6 +/- 14.5 microg x h/mL, compared to 70.0 +/- 13.4 microg x h/mL in controls. Statistically significant decreases (P<05) of AUC (33% change) and C(max) (36% change) in severely hepatically impaired subjects compared to controls--most likely secondary to ascites and edema--were not clinically relevant. Anidulafungin can be safely administered to patients with any degree of hepatic or renal impairment without dosage adjustment and without regard to hemodialysis schedules.