Beta-lactam / Beta-lactamase Inhibitor Combination Pregnancy: Safe in pregnancy — beta-lactam antibiotics are first-line in pregnancy; co-amoxiclav used in PPROM (preterm rupture of membranes)

Co-amoxiclav (Open Fracture Antibiotic Prophylaxis)

Brand names: Augmentin

Adult dose

Dose: 1.2 g IV every 8 hours (open fracture prophylaxis)

Route: Intravenous

Frequency: Every 8 hours

Max: 3.6 g/day (1.2 g every 8 hours); continue until definitive wound closure or for maximum 72 hours

BOAST Open Fracture Guidelines: co-amoxiclav 1.2 g IV is the recommended prophylactic antibiotic for open fractures from time of injury until definitive wound closure. First dose in Emergency Department — do NOT delay awaiting orthopaedic review. Add metronidazole for heavily contaminated wounds (soil, faeces, farmyard).

Paediatric dose

Dose: 30 mg/kg

Route: IV

Frequency: Every 8 hours

Max: 1.2 g every 8 hours

Paediatric open fracture prophylaxis — weight-based dosing; teaspoon oral formulations not equivalent to IV for open fracture prophylaxis (co-amoxiclav)

Dose adjustments

Renal

eGFR 10–30 mL/min: 1.2 g every 12 hours; eGFR <10 mL/min: 600 mg every 12 hours; haemodialysis: supplement dose after each session

Hepatic

Use with caution — co-amoxiclav-induced cholestatic hepatitis risk with hepatic impairment; monitor LFTs

Paediatric weight-based calculator

Patient weight (kg)

Paediatric open fracture prophylaxis — weight-based dosing; teaspoon oral formulations not equivalent to IV for open fracture prophylaxis (co-amoxiclav)

Clinical pearls

BOAST Open Fracture Guidelines (BOAST 4): co-amoxiclav 1.2 g IV should be given immediately on presentation in the Emergency Department for ALL open fractures — this is a time-critical intervention; delay increases infection risk
Heavily contaminated wounds (farmyard, soil, faeces): add metronidazole IV or rectal for anaerobic cover; consider tetanus prophylaxis status urgently
Co-amoxiclav cholestatic hepatitis: can occur up to 6 weeks AFTER stopping co-amoxiclav — presents with jaundice, elevated ALP/bilirubin; more common in older males; usually self-limiting but serious; report to MHRA via Yellow Card
Glandular fever precaution: aminopenicillins (amoxicillin, ampicillin, co-amoxiclav) cause a widespread maculopapular rash in EBV mononucleosis — NOT a true penicillin allergy but can be confused with one; check monospot if doubt
Duration: prophylaxis should NOT exceed 72 hours or definitive wound closure — prolonged antibiotic prophylaxis does not reduce infection further and increases C. difficile and antibiotic resistance risk

Contraindications

Penicillin hypersensitivity
Previous co-amoxiclav-associated cholestatic jaundice or hepatic impairment
Glandular fever (mononucleosis) — aminopenicillins cause widespread rash in EBV; check monospot before giving

Side effects

GI effects — nausea, diarrhoea, vomiting (most common)
Cholestatic hepatitis — more common than with amoxicillin alone; occurs up to 6 weeks after treatment
C. difficile diarrhoea
Hypersensitivity reactions — rash (distinguish from glandular fever rash)
Phlebitis at IV site

Interactions

Warfarin — broad-spectrum antibiotics reduce vitamin K-producing gut flora; monitor INR
Methotrexate — penicillins reduce renal tubular secretion of MTX; MTX toxicity risk
Oral contraceptives — theoretical interaction; current evidence does not support routine additional contraception

Monitoring

LFTs (cholestatic hepatitis risk)
Renal function
Signs of wound infection
GI symptoms — C. difficile if diarrhoea develops

Reference: BNFc; BNF 90; BOAST Open Fracture Guidelines 2017; NICE NG125 (SSI); SPC Augmentin IV. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways