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# Piperacillin/tazobactam (Zosyn)
## Overview
Piperacillin/tazobactam is a combination penicillin antibiotic and beta-lactamase inhibitor. It is active against a broad spectrum of gram-positive and gram-negative bacteria, including many anaerobes.
## Primary Indications
* Complicated intra-abdominal infections
* Complicated skin and skin structure infections
* Hospital-acquired pneumonia (including ventilator-associated pneumonia)
* Community-acquired pneumonia
* Febrile neutropenia (in combination with an aminoglycoside or as monotherapy in select patients)
* Various other serious infections, including those caused by piperacillin-resistant *Pseudomonas aeruginosa*.
## Adult Dosing
* **Standard Dosing:** 3.375 grams (3 g piperacillin/0.375 g tazobactam) intravenously every 6 hours.
* **Higher Dosing for *Pseudomonas aeruginosa* or severe infections:** 4.5 grams (4 g piperacillin/0.5 g tazobactam) intravenously every 6 or 8 hours.
* **Extended-infusion (preferred for higher doses):** 3.375 grams or 4.5 grams infused over 4 hours every 6 or 8 hours, respectively. This method can achieve higher drug concentrations and improve efficacy.
* **Maximum Dose:** Generally considered 18 grams per day (4.5 g every 6 hours). Dosing should be guided by institutional protocols and clinical judgment.
## Pediatric Dosing
Dosing in pediatric patients is complex and often weight-based, typically with piperacillin/tazobactam ratios of 8:1.
* **Children < 2 months:** Dosing is highly individualized and depends on gestational and postnatal age, weight, and renal function. Consultation with a pediatric infectious diseases specialist or pharmacist is recommended.
* **Children ≥ 2 months:** Dosing typically ranges from 80 mg/kg/day to 300 mg/kg/day of piperacillin, divided into 3 or 4 doses (or extended infusions). The tazobactam component is proportionally dosed. Specific guidelines should be followed (e.g., 100 mg/kg piperacillin / 12.5 mg/kg tazobactam every 8 hours, or 75 mg/kg piperacillin / 9.375 mg/kg tazobactam every 6 hours for extended infusion). **Always consult current pediatric dosing guidelines.**
## Dose Adjustments
* **Renal Impairment:**
* CrCl > 40 mL/min: No dose adjustment needed.
* CrCl 20-40 mL/min: Reduce frequency to every 8 hours.
* CrCl < 20 mL/min: Reduce frequency to every 12 hours.
* Dose should be adjusted to the piperacillin component.
* **Hepatic Impairment:** No dose adjustment is typically required, but caution is advised as hepatic function may affect drug elimination.
## Contraindications
* Hypersensitivity to piperacillin, tazobactam, other penicillin antibiotics, cephalosporins, or other beta-lactam agents.
* History of immediate or severe allergic reaction to piperacillin/tazobactam.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, rash, pruritus, headache, insomnia.
* **Serious:**
* Hypersensitivity reactions (including anaphylaxis).
* *Clostridioides difficile*-associated diarrhea.
* Seizures (especially with high doses or renal impairment).
* Hematologic effects (neutropenia, thrombocytopenia, leukopenia, eosinophilia, prolonged bleeding time).
* Hepatotoxicity.
* Acute kidney injury.
## Key Drug Interactions
* **Probenecid:** May increase and prolong piperacillin/tazobactam serum concentrations.
* **Neuromuscular blocking agents (e.g., vecuronium):** Piperacillin may prolong the neuromuscular blockade.
* **Warfarin:** Piperacillin may decrease the efficacy of warfarin; monitor INR closely.
* **Methotrexate:** Piperacillin may decrease methotrexate clearance; monitor methotrexate levels.
## Monitoring
* Renal function (BUN, creatinine) for dose adjustment.
* Liver function tests (AST, ALT, bilirubin) periodically.
* Complete blood count (CBC), including differential and platelet count, especially with prolonged therapy.
* Electrolytes.
* Signs and symptoms of hypersensitivity reactions.
* Signs and symptoms of *C. difficile*-associated diarrhea.
* Therapeutic drug monitoring is generally not required but may be considered in specific situations (e.g., critically ill patients, severe renal impairment).
## Clinical Pearls
* Extended infusion of 4 hours can improve the efficacy of piperacillin/tazobactam, particularly against *Pseudomonas aeruginosa*.
* Tazobactam extends the spectrum of activity to include many beta-lactamase-producing organisms.
* Piperacillin/tazobactam has significant activity against *Pseudomonas aeruginosa*; this is a key differentiator from other extended-spectrum penicillins.
* Monitor for signs of hypersensitivity reactions, which can be severe and delayed.
* Consider the potential for *C. difficile* infection with prolonged antibiotic use.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and institutional guidelines before administering any medication. Dosing and management may vary based on individual patient factors, local resistance patterns, and clinical context.
