Tissue distribution of amoxycillin after oral and intramuscular administration to pigeons (Columba livia)

Tissue distribution of amoxycillin in homing pigeons was studied after oral administration of amoxycillin trihydrate and after intramuscular injection of an oily amoxycillin suspension, both after a single dose of 100 mg/Kg. After the injection muscular damage at the injection site was studied by serum chemistry, and by macroscopic and histologic examination. After oral administration high peak levels were found in most tissues, but at 8 hours post-administration (p.a.) in most organs no drug levels could be detected. After intramuscular injection of the oily suspension lower peak levels were found in all organs, except the pectoral muscle contralateral to the injection site, but drug levels lasted at least till 60 hours p.a. After administration by both routes there was a fairly fixed relation between the tissue levels and the blood concentration for every organ. Very low concentrations were found in the brains. High levels were found after both routes of administration in the kidneys and the liver. After oral administration high levels were found also in the proventricular and intestinal wall. After intramuscular injection relative high concentrations were found in the duodenal and endgut wall. The damage to the pectoral muscle from the injection and the drug was small and restricted to mechanical destruction of muscle fibres by the needle and direct compression of the muscle fibres by the injected suspension.