The basic pharmacokinetics of micronomicin (MCR) were studied in 4 healthy adult volunteers. MCR 60 and 120 mg were intravenously administered in 30 and 60 minutes at constant rates by means of continuous infusion apparatus. The same dosages were also tested by intramuscular route. The concentrations of MCR in serum and urine were determined by HPLC and analyzed following the two-compartment open model after intravenous treatment and following the one-compartment open model after intramuscular treatment. When MCR was given by intramuscular route, the mean serum concentration of 4 subjects reached a peak of 3.98 micrograms/ml at 30 minutes after a dose of 60 mg and 6.7 micrograms/ml at 30 minutes after that of 120 mg. The peak concentration was achieved at the end of intravenous infusion and was dose-related, since it was 6.1 and 10.5 micrograms/ml after a 30-minute infusion of 60 and 120 mg, respectively, and 4.85 and 9.43 micrograms/ml after a 60-minute infusion of 60 and 120 mg, respectively. At 8 hours, concentrations dropped to less than 0.1 microgram/ml and to 0.2 microgram/ml or less after 60 and 120 mg, respectively, regardless of the route and rate of administration. The mean urinary recovery up to 8 hours ranged 84 to 92% of the dose. There were no appreciable differences in pharmacokinetic parameters among 4 modes of intravenous infusion, with a T1/2(beta) of 1.43 approximately 2.02 hours. In the case of intramuscular treatment, parameters analyzed following the one-compartment open model were on similar levels to corresponding values found after intravenous treatment and the T1/2 was 1.39 hours after 60 mg and 1.43 hours after 120 mg.(ABSTRACT TRUNCATED AT 250 WORDS)