Pharmacokinetics of cephalexin in the horse after intravenous and intramuscular administration of two formulations

摘要

Cephalexin is an effective and less expensive alternative to combinations of aminopenicillins with penicillinase-resistant penicillins or #beta#-lactamase inhibitors, for treatment of many infections in animals (Caprile, 1988) and, in the horse, it does not usually cause gastrointestinal side-effects (Sweeney & Boy, 1993). The pharmacokinetics of an oil suspension of sodium cephalexin administered intramuscularly (i.m.) in horses (Lees et al., 1990) shows that dosage (7mg/kg body weight b.i.d.) lower than those recommended for the 'non-retard' formulations (10-15 mg/kg body weight b.i.d./t.i.d.) (Prescott & Baggot, 1993) attains serum concentrations suitable for clinical efficacy. This study was performed to determine the pharmacokinetics of cephalexin in horses, and to compare the pharmacokinetic behaviour following i.m. injection of an aqueous 50 percent solution of cephalexin lysine salt (CPX_(water)) and a formulation containing 12.62 percent cephalexin monohydrate and 10.5 percent cephalexin benzathine in vegetable oil (CPX_(oils)).