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Pharmacology · Beta-lactams

Piperacillin + tazobactam !

An antipseudomonal penicillin protected by tazobactam; a broad-spectrum intravenous antibiotic for serious hospital infections.

Updated 2026-11-01

  • Class: Beta-lactams
  • Enzyme: Bacterial PBPs, mainly PBP3 (piperacillin), and β-lactamases (tazobactam)
  • ATC code: J01CR05
  • WHO Model List of Essential Medicines

Also called: piperacillin–tazobactam

The figure shows PBP3 from Pseudomonas aeruginosa with opened piperacillin bonded to the active-site serine.

Target in 3D: Bacterial PBPs, mainly PBP3 (piperacillin), and β-lactamases (tazobactam). PDB structure 6R3X (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Piperacillin is a ureidopenicillin: its polar side chain crosses the outer membrane of Pseudomonas aeruginosa and many enteric bacteria and binds mainly PBP3, which builds the division septum. Tazobactam barely binds PBPs but inhibits many class A β-lactamases (penicillinases and many ESBLs), so piperacillin is not destroyed. It also covers anaerobes such as Bacteroides fragilis.

  1. Tazobactam inactivates the bacterium's β-lactamases
  2. Piperacillin crosses the gram-negative outer membrane
  3. It acylates PBP3 and the bacterium cannot build its septum
  4. The bacterium elongates, weakens and lyses

Pharmacokinetics

Absorption
Intravenous only.
Elimination
Both are eliminated mainly by the kidney; adjusted in kidney failure.
Half-life
Short, under one hour for each component.

Indications

  • Complicated intra-abdominal infections (complicated appendicitis, peritonitis). Peritonitis →
  • Hospital-acquired pneumonia, with an aminoglycoside when Pseudomonas is suspected.
  • Complicated skin infections, including diabetic foot infection. Diabetic foot →
  • Postpartum endometritis and pelvic inflammatory disease. Pelvic inflammatory disease →

Adverse effects

Common

  • Diarrhoea, nausea, headache, insomnia
  • Rash, fever
  • Low potassium and a significant sodium load

Contraindications

  • History of allergy to penicillins, cephalosporins or β-lactamase inhibitors

Key interactions

Vancomycin
Higher rate of acute kidney injury; creatinine is monitored.
Aminoglycosides
Piperacillin inactivates them in vitro; they are given separately and their levels are monitored.
Heparin and oral anticoagulants
Higher bleeding risk; monitor coagulation.
Vecuronium and other non-depolarising neuromuscular blockers
May prolong neuromuscular blockade.
Methotrexate
May reduce its clearance; watch for toxicity.
Probenecid
Reduces tubular secretion: higher and longer-lasting β-lactam levels.

What is monitored

  • Creatinine and urine output, especially in critically ill patients or with vancomycin
  • Electrolytes (potassium, sodium)
  • Blood count and coagulation in long courses
  • Neurological status if there is kidney failure

Administration and safety

  • Intravenous only, by infusion.
  • Do not mix with aminoglycosides in the same bag or line; they are reconstituted and given separately.
  • Contains sodium: take it into account in salt-restricted or heart-failure patients.

Nursing care

  • Before the first dose: ask about allergy to penicillins, cephalosporins and other β-lactams, and what the reaction was.
  • Monitor urine output, creatinine and potassium during treatment.
  • Watch for bleeding gums, bruising or blood in urine or stools.
  • Watch for tremor, myoclonus or seizures in patients with kidney failure.
  • Teach the patient to report watery or bloody diarrhoea, even weeks after the course ends.

Pregnancy and breastfeeding

Both components cross the placenta; human data are not enough to define the risk, and it is used when the infection warrants it.

Test yourself

Think of the answer, then tap the question to see it.

Which PBP is piperacillin's main target in gram-negatives, and what happens when it is blocked?

PBP3, which builds the division septum; the bacterium grows into filaments and finally lyses.

Which combination with piperacillin + tazobactam raises the risk of acute kidney injury?

Combining it with vancomycin; creatinine and urine output are monitored.

What does tazobactam add if it has almost no antibacterial activity?

It inhibits many class A β-lactamases, including many ESBLs, so the bacterium cannot destroy piperacillin.

Why are piperacillin and gentamicin not mixed in the same line?

Because piperacillin inactivates the aminoglycoside in vitro; they are given separately.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Piperacillin and Tazobactam Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - PIPERACILLIN AND TAZOBACTAM injection, powder, for solution (DailyMed (U.S. National Library of Medicine), 2026); RCSB PDB - 6R3X: Structure of Pseudomonas aeruginosa Penicillin-Binding Protein 3 (PBP3) in complex with piperacillin (RCSB Protein Data Bank, 2026); Farmacología básica y clínica (Katzung), cap. 43 (McGraw Hill, 2025).

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Representative model, for educational purposes only.