CEPHALEXIN
For general information on the cephalosporins including adverse effects, contraindications, overdosage, drug interactions, and monitoring parameters, refer to the monograph: Cephalosporins, General Information.
Chemistry - A semi-synthetic oral cephalosporin, cephalexin (as the monohydrate) occurs as a white to off-white, crystalline powder. It is slightly soluble in water and practically insoluble in alcohol.
Pharmacology/Spectrum of Activity - A first generation cephalosporin, cephalexin exhibits activity against the bacteria usually covered by this class. Refer to the monograph: Cephalosporins,
General Information for more specific information.
States. It has been used clinically in dogs, cats, horses and birds, however.
Pharmacokinetics (specific) - After oral administration, cephalexin is rapidly and completelyabsorbed in humans. Cephalexin (base) must be converted to the HCl before absorption can occurand, therefore, absorption can be delayed. There is a form of cephalexin HCl commercially availablefor oral use which apparently is absorbed more rapidly, but the clinical significance of this is inquestion.
In a study done in dogs and cats (Silley et al. 1988), peak serum levels reached 18.6 micrograms/ml about 1.8 hours after a mean oral dose of 12.7 mg/kg in dogs, and 18.7 micrograms/ml, 2.6 hours after an oral dose of 22.9 mg/kg in cats. Elimination half-lives ranged from 1-2 hours inboth species. Bioavailability was about 75% in both species after oral administration.
In the U.K., an oily suspension of the sodium salt (Ceporex® Injection¯ Glaxovet) is apparentlyavailable for IM or SQ injection in animals. In calves, the sodium salt had a 74% bioavailabilityafter IM injection and a serum half-life of about 90 minutes.
Chemistry - A semi-synthetic oral cephalosporin, cephalexin (as the monohydrate) occurs as a white to off-white, crystalline powder. It is slightly soluble in water and practically insoluble in alcohol.
Storage, Stability, Compatibility
Cephalexin tablets, capsules, and powder for oral suspensionshould be stored at room temperature (15-30°C) in tight containers. After reconstitution, the oralsuspension is stable for 2 weeks.Pharmacology/Spectrum of Activity - A first generation cephalosporin, cephalexin exhibits activity against the bacteria usually covered by this class. Refer to the monograph: Cephalosporins,
General Information for more specific information.
Uses, Indications
There are no approved cephalexin products for veterinary use in the UnitedStates. It has been used clinically in dogs, cats, horses and birds, however.
Pharmacokinetics (specific) - After oral administration, cephalexin is rapidly and completelyabsorbed in humans. Cephalexin (base) must be converted to the HCl before absorption can occurand, therefore, absorption can be delayed. There is a form of cephalexin HCl commercially availablefor oral use which apparently is absorbed more rapidly, but the clinical significance of this is inquestion.
In a study done in dogs and cats (Silley et al. 1988), peak serum levels reached 18.6 micrograms/ml about 1.8 hours after a mean oral dose of 12.7 mg/kg in dogs, and 18.7 micrograms/ml, 2.6 hours after an oral dose of 22.9 mg/kg in cats. Elimination half-lives ranged from 1-2 hours inboth species. Bioavailability was about 75% in both species after oral administration.
In the U.K., an oily suspension of the sodium salt (Ceporex® Injection¯ Glaxovet) is apparentlyavailable for IM or SQ injection in animals. In calves, the sodium salt had a 74% bioavailabilityafter IM injection and a serum half-life of about 90 minutes.