Absorption and metabolism of tritium-labelled factor M 1 of virginiamycin by oral and parenteral administration.

After both intravenous injection and oral administration, the factor Js/L1 of virginiamycin was rapidly diluted or absorbed. It then disappeared from the plasma stream at a first order exponential rate with a half life of approximately 5hours following a process of both tissue fixation and body excretion. The bile was the main route by which the antibiotic was excreted from the body. The ratio CbM!./CpMi was nearly one, indicating that factor Mi was not actively transported from the liver to the bile though it is extensively metabolized to large polar fragments. After oral ingestion 15~18 % of the administrated factor Mt was absorbed through the gastro-intestinal tract. Neither bile nor the lymphatic system seemed to play a role in that absorption. The experimental data emphasized the importance of the plasmatic compartment as a reservoir for the antibiotic, the rapidity of tissular fixation and the special affinity of the factor Mxfor the skin. They correlated very well with the clinical trials which revealed the efficiency of the drug in the treatment of the gram-positive bacterial infections and the rapid onset of its action.