CEPHALEX

What it is

Cephalex is a semisynthetic cephalosporin antibiotic for oral administration. It is available as 250 mg and 500 mg capsules containing cephalexin monohydrate. Cephalex is bactericidal because of its inhibition of cell-wall synthesis.

Approved indications —

Respiratory tract infections caused by S. pneumoniae and group A beta-haemolytic streptococci — Bacterial sinusitis caused by streptococci, S. pneumoniae and methicillin-sensitive S. aureus — Otitis media due to S. pneumoniae and staphylococci — Skin and soft-tissue infections caused by staphylococci and/or streptococci — Genitourinary tract infections, including acute prostatitis caused by E. coli, P. mirabilis and Klebsiella sp.

Dosing overview

The adult dosage ranges from 1 to 4 g daily in divided doses, with the usual adult dose being 250 mg every 6 hours. For streptococcal pharyngitis or tonsillitis, mild uncomplicated urinary tract infections, and skin and soft tissue infections, a dosage of 500 mg may be administered every 12 hours. The usual recommended daily dosage for children is 25 to 50 mg/kg in divided doses. In the therapy of otitis media, a dosage of 75 to 100 mg/kg/day in 4 divided doses is recommended.

Key safety warnings

Before instituting therapy with Cephalex, every attempt should be made to determine if the patient has had previous hypersensitivity reactions to cephalosporins, penicillins or other drugs, and the product should be given cautiously to penicillin-sensitive patients. There is some clinical and laboratory evidence of partial cross-allergenicity of penicillins and cephalosporins, and patients have been reported to have had severe reactions including anaphylaxis to both drugs. Antibiotic-associated pseudomembranous colitis has been reported with virtually all broad-spectrum antibiotics, with a toxin produced by Clostridium difficile appearing to be the primary cause, and the severity of the colitis may range from mild to life-threatening. It is important to consider the diagnosis in patients who develop diarrhoea or colitis in association with antibiotic use, which may occur up to several weeks after cessation of antibiotic therapy. There have been reports of neurotoxicity associated with cephalosporin treatment, with symptoms including encephalopathy, seizures and/or myoclonus, and risk factors include being elderly, renal impairment, central nervous system disorders and intravenous administration. Severe cutaneous adverse reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms, and acute generalised exanthematous pustulosis have been reported in patients taking beta-lactam antibiotics, and when suspected, Cephalex should be discontinued immediately.

Contraindications

Cephalex is contraindicated in patients with known allergy to the cephalosporin group of antibiotics or who have previously experienced a major allergy to penicillin.

Regulatory history

Cephalex 250 mg and 500 mg capsules were first listed on the ARTG on 2 October 2013.