The pharmacokinetics of amikacin were investigated in five stable patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Each patient was studied after the administration of 7.5 mg of amikacin per kg by both the intravenous (i.v.) and intraperitoneal (i.p.) route, allowing a 1-month washout period between doses. No differences in amikacin half-life, volume of distribution, total body clearance, or time-averaged peritoneal clearance were noted between the two routes of administration. After a 5-h dwell period, bioavailability as calculated by the area under the curve for i.p. amikacin was 53 +/- 14.0%. Amikacin pharmacokinetics parallel those of other aminoglycosides in CAPD patients when the drug is administered either i.v. or i.p. Single loading doses of amikacin administered i.v. to uninfected CAPD patients provided therapeutic serum and dialysate levels for many aerobic gram-negative organisms for up to 72 h. Because of the variability of absorption of i.p. administered amikacin, single i.p. doses are not recommended.