indication

For the treatment of respiratory tract infections caused by Streptococcus pneumoniae and Streptococcus pyogenes; otitis media due to Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes, and Moraxella catarrhalis; skin and skin structure infections caused by Staphylococcus aureus and/or Streptococcus pyogenes; bone infections caused by Staphylococcus aureus and/or Proteus mirabilis; genitourinary tract infections, including acute prostatitis, caused by Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae.

pharmacology

Cephalexin (also called Cefalexin) is a first generation cephalosporin antibiotic. It is one of the most widely prescribed antibiotics, often used for the treatment of superficial infections that result as complications of minor wounds or lacerations. It is effective against most gram-positive bacteria.

mechanism of action

Cephalexin, like the penicillins, is a beta-lactam antibiotic. By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, it inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that cephalexin interferes with an autolysin inhibitor.

toxicity

Symptoms of overdose include blood in the urine, diarrhea, nausea, upper abdominal pain, and vomiting. The oral median lethal dose of cephalexin in rats is >5000 mg/kg.

biotransformation

No appreciable biotransformation in the liver (90% of the drug is excreted unchanged in the urine).

absorption

Well absorbed from the gastrointestinal tract

half life

1 hour

route of elimination

Cephalexin is excreted in the urine by glomerular filtration and tubular secretion. Studies showed that over 90% of the drug was excreted unchanged in the urine within 8 hours.