Pharmacokinetic evaluation of a slow-release cefotaxime suspension in the dog and in sheep.

Three Merino ewes were given cefotaxime IM, and 3 were given cefotaxime subcutaneously (50 mg/kg of body weight each); each dose was suspended in 6 ml of oil. Five dogs were also given an oily suspension of cefotaxime subcutaneously (SC) (50 mg/kg of body weight). The plasma concentrations (Cp) and pharmacokinetic data obtained after cefotaxime in the oily suspension was injected IM and SC were compared with data from the same animals after they were given an aqueous solution of cefotaxime by the same routes. Key pharmacokinetic values obtained after cefotaxime was administered IV to sheep and to dogs are discussed. Mean peak Cp (Cpeak) in sheep when given the oily suspension IM was approximately 53 micrograms/ml at 0.18 to 0.40 hour, and that value in sheep given the aqueous preparation was 62 micrograms/ml 0.08 to 0.18 hour. Mean Cpeak values after the oily suspension and the aqueous preparation were injected SC were 11.0 micrograms/ml (between 0.8 and 1 hour) and 51 micrograms/ml (between 0.25 and 1 hour), respectively. Bioavailabilities were approximately 70% after IM injection was done and 90% after SC injection was done. The beta-plasma half-lives were 0.7 hour after IM injection was done and 2.9 hours after SC injection was done. Mean Cpeak in dogs when given the oily suspension SC was 30 micrograms/ml at 1.0 hour, and when dogs were given the aqueous preparation SC, Cpeak was 27 micrograms/ml at 0.6 hour. Absorption was virtually complete after the oily suspension and aqueous preparations were given.(ABSTRACT TRUNCATED AT 250 WORDS)