Based on a review of the literature, a comparison is made of the pharmacokinetics of penicillins, aminoglycosides, and chloramphenicol in birds and mammals. Penicillins in birds are likely to be more dependent for their elimination on biotransformation than in mammals. Amoxycillin had a relatively low availability (0.34) after p.o. administration. Higher doses (2 to 8 times) were needed to achieve the same peak levels in birds and mammals. Aminoglycosides, which for their elimination largely depend on renal excretion by glomerular filtration, show only minor differences in pharmacokinetics between birds and mammals. Chloramphenicol is mainly excreted after biotransformation and large differences in pharmacokinetic parameters are to be found, not only between birds and mammals, but also between avian species.

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Three ampicillin and three amoxycillin formulations (tablets and capsules, administered orally, and oily suspensions, injected intramuscularly (i.m.) and subcutaneously (s.c.] were studied in twenty adult homing pigeons (Columba livia). Bioavailability, pharmacokinetics and recovery were determined for each product and administration route. A standard dose of 50 mg/pigeon or 100 mg/kg was used in each study. The mean availability calculated for each of these preparations was 7% for ampicillin anhydrate tablets, 22% for amoxycillin trihydrate tablets, 17% for ampicillin trihydrate capsules, 67% for amoxycillin trihydrate capsules, 46% for ampicillin oily suspension i.m., 67% for amoxycillin oily suspension i.m. and 43% for amoxycillin oily suspension s.c. The blood concentration-time curves for the tablets were very scattered, which was far less the case for the capsules. The maximum blood concentration (Cmax) for amoxycillin was twice as high as for ampicillin. The Cmax resulting from the oily suspensions administered i.m. were low (4.35 +/- 1.05 and 5.04 +/- 1.36 mg/l, for ampicillin and amoxycillin, respectively). The Tmax for ampicillin was 10 h and for amoxycillin it was 0.9 h after administration. Both curves showed biphasic absorption, the initial peak representing an absorption and a distribution phase and the second part reflecting the 'depot-nature' of the drug. After the s.c. administration of the amoxycillin oily suspension the same pattern was found, but the Cmax, which was found at 2.13 +/- 1.03 h after administration, was low (2.81 +/- 0.68 mg/l).(ABSTRACT TRUNCATED AT 250 WORDS)

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.