[Absorption, distribution and excretion of 14C-josamycin and 14C-josamycin propionate in rats (author's transl)].

Abosrption, distribution and excretion of 14C-josamycin (JM) and 14C-josamycin propionate (JM-P) were studied in rats by measuring both antibacterial activity and radioactivity. 1. In antibacterial activity, plasma and tissue concentrations of JM-P showed a similar tendency to those of JM. Those concentrations of JM reached a peak at 1 hour after administration with a subsequent rapid decrease, while the peak level of JM-P appeared 2 approximately 4 hours after administration and then fell down very slowly. 2. In radioactivity, oral administration of JM-P rapidly produced a very high plasma and tissue concentrations which were in lung, liver, kidney and spleen more than twice those of JM. These results showed that when given orally, JM-P is well absorbed with distributions at high concentrations especially in lung, liver, and kidney and spleen. 3. The ratios of bioactivity/radioactivity in JM administration were the highest in lung and the lowest in liver at 1 hour after. But those of JM-P were generally much lower than those of JM because of higher distribution of JM-P radioactivity into tissues. 4. Four days after oral administration of JM and JM-P, 23.1% and 21.8% of the given radioactivity were recovered respectively from urine. However, the antibacterial activities recovered were 0.40% for JM and 0.65% for JM-P. 5. Biliary recoveries of JM and JM-P were 17.2% and 12.1% of administered radioactivity 2 days after oral administration. On the other hand, 0.47% of JM and 0.17% of JM-P were excreted into bile as antibacterial activity. These results showed that JM and JM-P were excreted into rat urine and bile as some metabolites with less biological activity. 6. The amounts of JM and JM-P recovered from feces were 75.7% and 60.2%, respectively, of the orally given radioactivity. The amount of radioactivity recovered from expiration air was about 1% of either orally given JM or JM-P.