Pharmacokinetics of clindamycin HCl administered intravenously, intramuscularly and subcutaneously to dogs

A buffered aqueous solution of clindamycin Hcl (200 mg/mL) was injected intravenously (i.v.) intramuscularly (i.m.) and subcutaneously (s.c.) in a non-randomized, partial cross-over trial involving six male and six female dogs. Blood samples were collected at conventional, predetermined time periods and serum drug concentrations were determined by microbiological assay. Dogs were observed clinically for signs of pain, and activity of serum creatine phosphokinase (CPK) was monitored after i.m. dosing. The i.v. data from five of the dogs best fitted a two-compartment open-system pharmacokinetic model whereas a non-compartment model was most suitable for analysis of the data from the remaining seven dogs. The mean i.v. elimination half-life (t1/2 beta) and the mean residence time (MRT) were 124 and 143 min, respectively. The mean volume of distribution at steady state (Vss) was 0.86 L/kg. Little pain was recorded upon i.m. injection; mean peak serum drug concentration (Cmax) was 4.4 micrograms/mL, the elimination half-life (t1/2el) was 247 min and the calculated bioavailability (F) was 115% of the i.v. dose. Serum CPK activity was elevated to 25-fold the pretreatment level in samples collected 4, 8 and 12 h after i.m. injection. Pain was not recorded after s.c. drug administration; the mean Cmax of 20.8 micrograms/mL was significantly greater than the corresponding value for the i.m. route, and F was 310%. The s.c. route appears to be superior to the i.m. route in terms of local tolerance and serum drug level; a 10 mg/kg SID treatment regimen is suggested for treatment of canine infections due to clindamycin sensitive bacteria.     

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

OBJECTIVE: To determine tissue depletion profiles for gentamicin and its 3 major components (C1, C1a, and C2) in turkeys. ANIMALS: Twenty 10-week-old male turkeys. PROCEDURE: 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. RESULTS: 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. CONCLUSIONS AND CLINICAL RELEVANCE: 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.