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# Piperacillin/Tazobactam
## Overview
A fixed-ratio combination of a ureidopenicillin (piperacillin) and a beta-lactamase inhibitor (tazobactam). It provides expanded-spectrum activity against many Gram-positive, Gram-negative, and anaerobic organisms, including *Pseudomonas aeruginosa*.
## Primary Indications
* Moderate to severe intra-abdominal infections.
* Nosocomial and ventilator-associated pneumonia.
* Skin and skin structure infections.
* Empiric treatment of febrile neutropenia.
* Complicated urinary tract infections.
## Adult Dosing
Standard dose is 3.375 g (3 g piperacillin/0.375 g tazobactam) IV every 6 hours.
* **Severe infections:** 4.5 g (4 g piperacillin/0.5 g tazobactam) IV every 6 hours.
* **Max dose:** 18 g total piperacillin daily (4.5 g every 6 hours).
* **Administration:** Typically infused over 4 hours for critically ill patients to optimize pharmacodynamics (time above MIC).
## Pediatric Dosing
* **Neonates (≤ 40 weeks postmenstrual age):** 80 mg/kg/day (piperacillin component) divided every 8–12 hours.
* **Children ≥ 9 months:** 240–300 mg/kg/day (based on piperacillin) divided every 6–8 hours.
* **Max dose:** Usually 16 g piperacillin/day (consult institutional pediatric protocols for precise weight-based caps).
## Dose Adjustments
* **Renal Impairment:** Must be adjusted based on creatinine clearance (CrCl).
* CrCl 20–40 mL/min: 2.25 g every 6 hours.
* CrCl < 20 mL/min: 2.25 g every 8–12 hours.
* Patients on hemodialysis require a supplemental dose post-dialysis.
* **Hepatic Impairment:** No dose adjustment necessary.
## Contraindications
* Known hypersensitivity to piperacillin, tazobactam, or any component of the penicillin, cephalosporin, or beta-lactamase inhibitor classes (due to potential cross-reactivity).
## Adverse Effects
* **Common:** Diarrhea, constipation, nausea, headache, insomnia.
* **Serious:** *Clostridioides difficile*-associated diarrhea, hypersensitivity reactions (anaphylaxis), rash (including DRESS/SJS), leucopenia/neutropenia (with prolonged use), and seizures (primarily in patients with renal failure).
## Key Drug Interactions
* **Aminoglycosides:** Piperacillin can inactivate aminoglycosides *in vitro*; do not mix in the same IV line. Administer at least 1 hour apart.
* **Probenecid:** Increases serum concentrations of piperacillin/tazobactam.
* **Methotrexate:** Penicillins may decrease renal clearance, increasing risk of toxicity.
* **Warfarin:** Theoretical risk of increased bleeding due to platelet aggregation inhibition.
## Monitoring
* **Renal function:** Monitor BUN and serum creatinine; adjust dose as needed.
* **Hematology:** Periodic CBC, especially with therapy > 14 days (risk of neutropenia/thrombocytopenia).
* **Electrolytes:** Monitor for hypokalemia (piperacillin is a sodium salt; watch for hypernatremia).
* **Signs/Symptoms:** Monitor for hypersensitivity reactions and *C. difficile* symptoms.
## Clinical Pearls
* **Stability:** Once reconstituted/diluted, stability is limited; follow institutional protocols for storage duration.
* **Synergy:** The tazobactam component extends the spectrum to include beta-lactamase-producing organisms (*E. coli*, *Klebsiella*, *Bacteroides*) but does not improve activity against organisms that are intrinsically resistant to piperacillin.
* **Administration:** Extended/prolonged infusion (4 hours) is increasingly utilized to improve outcomes in high-MIC infections or critically ill patients.
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*Disclaimer: This information is for educational purposes only. Always consult your institution’s antimicrobial stewardship guidelines, the official FDA-approved package insert, or a clinical pharmacist before prescribing or administering medication, as clinical protocols may vary.*
