Pharmacokinetics and tissue tolerance of azithromycin after intramuscular administration to rabbits.

Author(s): Escudero E, Fernandez-Varon E, Marin P, Espuny A, Najera MD, Carceles CM

Affiliation(s): Departamento de Farmacologia, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, 30071 Murcia, Spain. escudero@um.es

Publication date & source: 2006-12, Res Vet Sci., 81(3):366-72. Epub 2006 Mar 10.

Publication type: Clinical Trial; Research Support, Non-U.S. Gov't

The pharmacokinetics of azithromycin after intravenous and intramuscular injection at a single dose rate of 10mg/kg bodyweight were investigated in rabbits by using a modified agar diffusion bioassay for determining plasma concentrations. The plasma creatine kinase activity was determined after i.m. administration for the evaluation of the tissue tolerance. The elimination half-lives of azithromycin after intravenous and intramuscular administration were 24.1 and 25.1h, respectively. After intramuscular administration mean peak plasma concentration was 0.26+/-0.01 mg/L and bioavailability was 97.7%. Plasma CK activity rose sharply within 8h after i.m. injection of azithromycin; activity returned to pre-treatment level by 48-72 h post-treatment. The transient rise in serum CK activity indicates some degree of muscle tissue damage at the injection site.