cefalexin monohydrate: clinical use

Prescribing considerations

• Confirm that infection is bacterial and likely to involve susceptible organisms; review microbiology results when available.
• Clarify previous cephalosporin, penicillin and other beta-lactam reactions.
• Consider renal function, age, neurological disease and concurrent nephrotoxic medicines.
• Investigate significant diarrhoea during or after treatment for antibiotic-associated colitis.
• Review prolonged use for superinfection with non-susceptible organisms.

Contraindications and cautions

• Known hypersensitivity to cefalexin, another cephalosporin or a product excipient.
• Use particular caution with previous immediate or severe beta-lactam hypersensitivity.
• Marked renal impairment increases accumulation and cephalosporin-associated neurotoxicity risk.
• Check formulation-specific excipients where sugar, sorbitol, sodium benzoate, lactose or colouring agents are clinically relevant.

Monitoring

• Renal function where impairment, older age or nephrotoxic co-treatment makes accumulation more likely.
• Clinical response and available culture or susceptibility results.
• New rash, anaphylaxis, severe diarrhoea, superinfection or neurological symptoms.
• Interpret direct Coombs testing and some urine glucose methods with awareness of possible interference.

Clinical pharmacology

An acid-stable, bactericidal first-generation cephalosporin that inhibits bacterial cell-wall synthesis. It is rapidly absorbed orally and eliminated mainly unchanged through the kidneys; renal impairment prolongs exposure.

Formulation and product differences

• Selected products include hard capsules, scored tablets and powders or granules requiring reconstitution as oral suspension.
• The selected tablet score facilitates swallowing and does not produce equal portions.
• Reconstituted suspension storage conditions and discard dates vary by product.
• Liquid and capsule excipients differ between products.

Capsule

Route: Oral

Strengths: 250 mg, 500 mg

Oral suspension

Route: Oral

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