[Clinical studies of intravenous drip infusion of micronomicin. 1. Absorption and excretion].

UNLABELLED

Pharmacokinetics of MCR administered by 1 hour intravenous drip infusion were studied in healthy volunteers by two-compartment model. In 120 mg-dosage group (n = 3) studies were made by single administration, and in 60 mg-dosage group (n = 4) were administered twice daily and continued until a total of 9 doses.

RESULTS

When MCR was administered in a 60 mg dosage, its Cmax was 4.3 +/- 0.3 micrograms/ml (mean +/- S.D.) after the 1st dose and 3.7 +/- 0.4 micrograms/ml after the 9th dose, while it was 8.8 +/- 1.0 micrograms/ml when the dosage was 120 mg. It should be noted that in the case of repeated dosing with 60 mg, serum levels just before administration were always below the analytical limit. The mean of T 1/2 was 1.69 +/- 0.14 hours, remaining stable at all determination. The kinetic parameters that showed different values between determinations performed after the 1st and 9th 60 mg doses were V1 (0.107 vs 0.164 L/kg) and Kel (1.02 vs 0.68 hr-1). This was also the case with comparison of 2 different dosage groups (60 mg 1st vs 120 mg; V1: 0.107 vs 0.135 L/kg, Kel: 1.02 vs 0.72 hr-1). There was no evidence indicative of side effect of MCR.

DISCUSSION

The above results demonstrated that Cmax and other kinetic parameters were little influenced by whether MCR was administered by intravenous drip infusion or by intramuscular injection. There was a little larger difference in AUC between those 2 routes of administration but the differences seemed negligible when the same dosage was used. Pharmacokinetic studies are to be continued in subjects whose renal function is impaired in different ways to establish the optimum dosage regimen for MCR.