Abstract
The absorption, distribution and excretion of DR-3355, a new quinolone antimicrobial agent, were investigated in male rats after a single oral administration of 14C-DR-3355 at a dose of 20 mg/kg.
1. The radioactivity was rapidly and completely absorbed in rats after an oral administration of 14C-DR-3355. Cmaxs in the blood and serum were attained at 0.5hr reaching concentrations of 2.51 and 3.23μg equiv. to DR-3355/ml, respectively. Blood levels of radioactivity decreased with a half life of 1.7hr, and the concentrations at 24hr were below 0.05μg equiv. to DR-3355/ml.
2. DR-3355 distributed to all tissues except the central nervous system and the adipose tissue. Tissue concentration profiles of radioactivity were almost parallel to that of blood. Autoradiograms showed that radioactivity disappeared from most of tissues at 72hr after administration.
3. Blood cell binding and serum protein binding were almost independent of time, and corresponding binding values were 28 ?? 33 and 40 ?? 51%, respectively.
4. Most of radioactivity was excreted into urine (43.8%) and feces (56.8 %) within 48hr. Cumulative biliary and urinary excretions were 57.4% and 36.8% in bile duct-cannulated rats, respectively. These results indicated that fecal excretion of radioactivity was mainly derived from biliary excretion and radioactivity was reabsorbed by enterohepatic circulation.
