Cephalexin is indicated for the treatment of the following infections caused by susceptible organisms:

• Respiratory tract infections: Acute and chronic bronchitis, and infected bronchiectasis
• Genito-urinary tract infections: Acute and chronic nephritis, cystitis, urethritis, prostatitis, and prophylaxis of recurrent urinary tract infections
• Skin and soft tissue infections: Infections caused by staphylococci and/or streptococci
• Ear, nose and throat infections: Otitis media, mastoiditis, sinusitis, follicular tonsillitis, and pharyngitis
• Bone infections: Infections caused by staphylococci and/or P. mirabilis

Cephalexin is a semisynthetic analogue of cephalosporin C. It acts by interfering with bacterial cell wall synthesis. Peptidoglycan, a heteropolymeric structure, provides mechanical strength to the bacterial cell wall. The final stage of peptidoglycan synthesis involves cross-linking, in which the terminal glycine residue of the pentaglycine bridge is linked to the fourth residue of the pentapeptide (D-alanine). This step is catalyzed by the transpeptidase enzyme, which is inhibited by penicillins and cephalosporins. As a result, the bacterial cell wall is weakened, the cell swells, and eventually ruptures. Cephalexin is a first-generation cephalosporin that is active when taken orally.

Adult:

• The usual dose is 250 mg to 500 mg every 6 hour.
• For skin and soft tissue infections, streptococcal pharyngitis and uncomplicated cystitis, in patients over 15 years of age: 500 mg of the drug may be administered every 12 hour.
• In severe or deep seated infections the dose can be increased up to 3 g to 6 g daily.

Children: The dosage range is 25-100 mg/kg/day in divided doses to a maximum of 4 g daily

Children's Weight Recommended Dose:

• 10 kg (22 Ibs): 62.5 mg to 125 mg qid or 125 mg to 250 mg bid
• 20 kg (44 Ibs): 125 mg to 250 mg qid or 250 mg to 500 mg bid
• 40 kg (88 Ibs): 250 mg to 500 mg qid or 500 mg to 1 g bid

For streptococcal pharyngitis, skin and soft tissue infections and in patients over 1 year of age the total daily dose may be divided and administered every 12 hour. In the therapy of otitis media 75-100 mg/kg/day in four divided doses may be required. In the treatment of β haemolytic streptococcal infections a therapeutic dosage of the drug should be given at least for 10 days.

Cephalexin is contraindicated in patients with known hypersensitivity to the cephalosporin group of antibiotics.

Side effects of cephalexin include nausea, vomiting, diarrhea, and abdominal discomfort. Symptoms of pseudomembranous colitis may occur during or after antibiotic treatment. Skin rash, angioedema, increased serum aminotransferases, eosinophilia, and neutropenia have been reported very rarely. Treatment may also lead to superinfection with resistant microorganisms, particularly Candida.

Cephalexin is classified as Pregnancy Category B. It may be used during pregnancy when clearly necessary. Cephalexin is excreted in the breast milk of nursing mothers; therefore, caution should be exercised when it is administered during breastfeeding.

Cephalexin should be used with caution in patients with renal impairment. In such cases, careful clinical monitoring is necessary, as the safe dosage may be lower than the usually recommended dose. The urine of patients receiving cephalexin may show a false-positive reaction for glucose when tested with copper reduction reagents. Positive Coombs’ test results have also been reported. Although animal studies have shown no evidence of teratogenicity, cephalexin should be used during pregnancy only when considered essential. Since cephalexin is present in breast milk, caution is advised when it is given to nursing mothers.

First-generation cephalosporin antibiotic.

Store in a cool and dry place.