cefalexin: clinical use

Prescribing considerations

• Confirm that the presentation is appropriate for oral treatment and that the suspected or proven organism is susceptible.
• Review previous immediate beta-lactam reactions, severe antibiotic-related skin reactions and antibiotic-associated colitis.
• Assess renal function where impairment is known or suspected because cefalexin is predominantly renally eliminated.
• Review formulation excipients, especially for young children, hereditary sugar intolerance, dietary requirements or allergies.
• Consider culture results and the risk of overgrowth by non-susceptible organisms during prolonged exposure.

Contraindications and cautions

• Known hypersensitivity to cefalexin or other cephalosporins.
• Selected oral suspensions are contraindicated in porphyria; check the product-specific information.
• Selected sugar-containing formulations are unsuitable for certain rare hereditary disorders of carbohydrate metabolism.
• Oral cefalexin is inappropriate during the acute stage of a severe systemic infection requiring parenteral cephalosporin treatment.

Monitoring

• Clinical response and evidence of superinfection.
• Renal function when impairment or concurrent nephrotoxic treatment is relevant.
• Severe or persistent diarrhoea and features of antibiotic-associated colitis.
• Skin and systemic hypersensitivity reactions.
• Coagulation where clinically relevant, particularly with oral anticoagulants.
• Possible drug-related positive direct Coombs tests and false-positive urine glucose results with some reduction-based methods.

Clinical pharmacology

An orally absorbed, first-generation beta-lactam cephalosporin that inhibits bacterial cell-wall synthesis. It has low protein binding, distributes into several tissues and is eliminated mainly in active form through the kidneys; elimination is prolonged when renal function is reduced.

Formulation and product differences

• Selected products include film-coated tablets, hard capsules and granules reconstituted as oral suspension.
• Selected tablets contain lactose; selected capsules have a gelatine shell.
• Selected suspensions contain sucrose and excipients requiring age-, allergy- or intolerance-specific consideration, including sodium benzoate and traces of benzyl alcohol.
• Reconstituted suspensions require refrigerated storage and have a limited in-use shelf life; follow the product label and product-specific information.

Capsule

Route: Oral

Strengths: 500 mg

Oral suspension

Route: Oral

Strengths: 125 mg/5 mL, 250 mg/5 mL

Tablet

Route: Oral

Strengths: 250 mg, 500 mg