Pharmacology: Pharmacodynamics: Cephalexin is bactericidal; its action depending on its ability to bind penicillin-binding proteins located in bacterial cytoplasmic membranes. Cephalexin inhibits synthesis of bacterial septum and cell wall probably by acylation of transpeptidases enzymes. These enzymes are responsible for the cross linking of peptidoglycan chains, which is necessary for the bacterial cell wall strength and rigidity. Cell division and growth are also inhibited. Rapidly dividing bacteria are those most susceptible to the action of cephalexin.
Pharmacokinetics: Cephalexin is almost completely absorbed from the gastrointestinal tract. If cephalexin is taken with food, absorption may be delayed, but the total amount absorbed is not appreciably altered. It is widely distributed in the body but does not enter the cerebrospinal fluids in significant quantities. It is not metabolised. About 80% or more of a dose is excreted unchanged in the urine.