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Extended-spectrum beta-lactam + beta-lactamase inhibitor Pregnancy: Use if clearly indicated — limited human data but penicillin class generally safe.

Piperacillin/Tazobactam

Brand names: Tazocin

Adult dose

Dose: 4.5 g every 6–8 hours IV
Route: IV infusion over 30 min (or extended infusion over 4 hours in ICU)
Frequency: Every 6 hours (severe/ICU) or every 8 hours
Max: 18 g/day (piperacillin component)
Standard: 4.5 g every 8 hours. Severe / ICU / neutropenic sepsis: 4.5 g every 6 hours. Extended infusion (4 hours): increasingly used in critical care to maximise pharmacodynamic target attainment. Duration typically 5–7 days.

Paediatric dose

Dose: 90 mg/kg
Route: IV
Frequency: Every 6–8 hours
Max: 4.5 g/dose
Concentration: 200 mg/ml
2–11 years: 90 mg/kg every 8 hours; up to 112.5 mg/kg every 8 hours in severe infections. ≥12 years: adult dose. Neonates: specialist guidance required.

Dose adjustments

Renal

eGFR 20–40: 4.5 g every 8 hours; eGFR <20: 4.5 g every 12 hours.

Hepatic

No significant dose adjustment required.

Paediatric weight-based calculator

2–11 years: 90 mg/kg every 8 hours; up to 112.5 mg/kg every 8 hours in severe infections. ≥12 years: adult dose. Neonates: specialist guidance required.

Clinical pearls

  • Broad-spectrum Gram-positive, Gram-negative (including Pseudomonas), and anaerobic coverage
  • First-line empirical therapy for neutropenic sepsis, aspiration pneumonia, intra-abdominal sepsis
  • Restricted in many NHS trusts due to C. difficile and ESBL selection pressure
  • MERINO trial: did not find superiority over meropenem for Enterobacteriaceae bacteraemia — meropenem preferred for ESBL producers
  • High sodium content (64 mmol per 4.5 g vial) — monitor sodium in renal/cardiac patients

Contraindications

  • Penicillin hypersensitivity

Side effects

  • Diarrhoea and GI upset
  • Hypersensitivity reactions
  • Electrolyte disturbances (hyponatraemia — high sodium load in IV preparation)
  • Elevated transaminases
  • Thrombocytopenia and haematological effects
  • Seizures (high doses, renal failure)

Interactions

  • Aminoglycosides — incompatible in same IV line (administer separately); synergistic anti-pseudomonal effect
  • Methotrexate — reduced excretion
  • Vecuronium — prolonged neuromuscular blockade

Monitoring

  • U&E (electrolytes)
  • LFTs
  • FBC
  • Response to treatment (procalcitonin, CRP, WCC)

Reference: BNFc; BNF; NICE NG51 Neutropenic Sepsis; PHE Antimicrobial Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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