Depletion of gentamicin and its major components from various tissues of turkeys

To determine tissue depletion profiles for gentamicin and its 3 major components (C1, C1a, and C2) in turkeys. Twenty 10-week-old male turkeys. birds were maintained as untreated controls. The remaining birds were treated with gentamicin sulfate at a dosage of 2 mg/kg, IM, once daily for 5 days. Treated birds were euthanatized 45, 60, 75, and 90 days (4 birds at each sample time) after the last dose of gentamicin was administered, and samples of muscle, liver, kidney, and skin and fat were collected. Control birds were euthanatized on day 45. Concentrations of the 3 major components of gentamicin were measured by means of reversed-phase high-performance liquid chromatography. Total gentamicin concentration (ie, sum of the concentrations of the 3 major components) was < 100 microg/kg for all muscle and skin and fat samples by day 45 and all liver samples by day 75. At all sample times, concentration of the gentamicin C1 component was higher than concentrations of the C1a and C2 components in all tissues. Results suggest that tissue depletion profiles of the 3 major components of gentamicin differ from each other. Withdrawal time, therefore, may depend on the ratio of the components in the pharmaceutical preparation used.