Pharmacokinetics and local tolerance of a long-acting oxytetracycline formulation in camels

Abstract

SUMMARY Disposition and local tolerance of a new oxytetracycline (otc) long-acting formulation were evaluated in camels by measuring the dynamics of creatine kinase. Six camels (Camelus dromedarius) were administered otc by iv and im routes according to a 2-period cross-over, study design. Serum otc concentration was measured, using a microbiological assay procedure. After iv administration (5 mg/ kg of body weight), mean residence time was 7.7 ± 2.8 hours, steady-state volume distribution was 706.1 ± 168.6 ml·kg-1 and serum clearance was 75.3 ± 23.2 ml·kg-1·h-1. After im administration of the long-acting otc formulation (10 mg/kg), maximal otc concentration (3.49 ± 0.44 μg·ml-1) was observed after 7.3 ± 3.5 hours; the mean systemic availability was near 100%, and serum concentration > 0.5 μg>ml-1 was maintained for about 72 hours. After im administration, mean control serum activity of creatine kinase was multiplied by a factor of 3.36 ± 1.55; at 72 hours after otc administration, the serum creatine kinase activity returned to control values. It was concluded that otc is an antibiotic of potential interest in camels and that a dosage regimen of 10 mg>kg-1 deserves attention when using a long-acting formulation that has good local tolerance and near total systemic availability.