[Tissue levels following intravenous administration of tetracyclines (author's transl)].

Interested by a comparative trial on tetracycline concentrations in gallbladder, bile and peritoneum 3 hours after administration, we wanted to know the long-term tissue concentrations, measured towards the end of a 24-hour off-drug interval, as these concentrations are particularly important for a bacteriostatic drug. We found that the tissue concentrations of doxycycline in gallbladder wall, lung, muscle, and thyroid gland were 2 to 3 times higher than those of pyrrolidino-methyltetracycline. The concentrations in the skin, in various sections of the intestinal tract and of the peritoneum, and in the gallbladder content were about the same for both drugs. The implications of these data for therapy are discussed.