title: Pharmacokinetics and tissue localization of doxycycline polyphosphate and doxycycline hydrochloride in the rat.
abstract: Two doxycycline derivatives Doxycycline polyphosphate and Doxycycline hydrochloride were administered to rats at a dose of 20 mg/kg body weight. Doxycycline tissue levels were determined using a microbiological assay. Only an insignificant fraction of the antibiotics was found to cross the blood brain barrier. Doxycycline was highly concentrated in excretory organs: liver, kidneys and caecum. The high intestinal drug level observed is probably related to the entero-hepatic cycle of this antibiotic. There was a good correlation between serum and heart doxycycline concentration; heart level was about twice that of serum. In lung, antibiotic level was always higher than in serum.
mesh_terms: D000818:Animals; D004318:Doxycycline / Q000031:analogs & derivatives* / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
chemical_list: C041809:doxycycline polyphosphate; D004318:Doxycycline