Co-amoxiclav: clinical use

Prescribing considerations

• Confirm a bacterial indication and consider likely pathogens, susceptibility, infection site and severity.
• Review renal and hepatic function and select an appropriate formulation; different amoxicillin-to-clavulanate ratios are not interchangeable.
• If culture results show susceptibility to amoxicillin alone, consider narrowing therapy in accordance with local antimicrobial policy.
• Avoid where infectious mononucleosis is suspected because amoxicillin-associated morbilliform rash is more likely.
• Maintain adequate hydration and urine output where crystalluria risk is relevant.

Contraindications and cautions

• Hypersensitivity to amoxicillin, clavulanic acid, any penicillin or product excipient
• Previous severe immediate hypersensitivity reaction to another beta-lactam
• Previous jaundice or hepatic impairment caused by amoxicillin–clavulanic acid

Monitoring

• Renal function where impairment, older age or substantial exposure may increase accumulation risk
• Hepatic function in hepatic impairment and when clinically indicated
• Renal, hepatic and haematological function during prolonged therapy
• INR or prothrombin time with oral anticoagulants
• Clinical response, microbiology and evidence of superinfection or antibiotic-associated colitis

Clinical pharmacology

Amoxicillin is a time-dependent beta-lactam that inhibits bacterial peptidoglycan synthesis. Clavulanic acid has little useful antibacterial activity alone but irreversibly inhibits certain beta-lactamases. Both are rapidly absorbed orally, cross the placenta and are substantially eliminated through renal pathways; clavulanate also undergoes non-renal elimination.

Formulation and product differences

• Oral products include tablets and suspensions with differing amoxicillin-to-clavulanate ratios; product selection must preserve the intended ratio.
• Oral suspensions require reconstitution, shaking and product-specific refrigerated storage after preparation. Some contain aspartame, requiring consideration in phenylketonuria.
• The selected intravenous formulation contains sodium and potassium, is not for intramuscular use and has specific compatibility, preparation and administration requirements.
• Oral treatment may follow intravenous treatment when clinically appropriate.

Oral suspension

Route: Oral

Strengths: 125 mg + 31.25 mg/5 mL, 250 mg + 62.5 mg/5 mL, 400 mg + 57 mg/5 mL

Tablet

Route: Oral

Strengths: 250 mg + 125 mg, 500 mg + 125 mg, 875 mg + 125 mg