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# Piperacillin-Tazobactam (Zosyn)
## Overview
Piperacillin-tazobactam is a combination penicillin-class antibiotic and beta-lactamase inhibitor. It has broad-spectrum activity against many gram-positive, gram-negative, and anaerobic bacteria.
## Primary Indications
* Complicated intra-abdominal infections
* Complicated skin and skin structure infections
* Community-acquired pneumonia
* Hospital-acquired pneumonia (including ventilator-associated pneumonia)
* Febrile neutropenia (empiric treatment)
## Adult Dosing
Standard dose: 3.375 grams (3g piperacillin/0.375g tazobactam) every 6 hours or 4.5 grams (4g piperacillin/0.5g tazobactam) every 6 or 8 hours intravenously.
Dosing frequency and duration depend on the indication, severity of illness, and pathogen(s). Higher doses may be used for severe infections or for specific pathogens. Maximum daily dose for piperacillin is typically 18g.
## Pediatric Dosing
* **3 months to 12 years:** Dosing is based on piperacillin component: 80-100 mg/kg/dose (piperacillin equivalent) every 6 or 8 hours. Doses should not exceed the adult maximum dose. For febrile neutropenia, 100 mg/kg/dose every 8 hours.
* **Neonates and infants younger than 3 months:** Dosing is less established and should be guided by specialist recommendations and pharmacokinetic data. Dosing regimens vary.
## Dose Adjustments
* **Renal Impairment:**
* CrCl ≥ 40 mL/min: No adjustment needed.
* CrCl 20-39 mL/min: Administer 2.25g (2g piperacillin/0.25g tazobactam) or 3.375g (3g piperacillin/0.375g tazobactam) every 8 hours.
* CrCl < 20 mL/min: Administer 2.25g (2g piperacillin/0.25g tazobactam) or 3.375g (3g piperacillin/0.375g tazobactam) every 12 hours.
* Consider intermittent hemodialysis and continuous renal replacement therapy (CRRT) dose adjustments as per institutional guidelines.
* **Hepatic Impairment:** No specific dose adjustment is generally recommended.
## Contraindications
* Known history of severe allergic reaction to piperacillin, other penicillins, cephalosporins, beta-lactamase inhibitors, or any component of the formulation.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, rash, pruritus, insomnia, headache, fever, phlebitis/thrombophlebitis at the injection site.
* **Serious:** Hypersensitivity reactions (including anaphylaxis), *Clostridioides difficile*-associated diarrhea, seizures (rare, usually with high doses or renal impairment), neutropenia, thrombocytopenia, elevated liver enzymes, interstitial nephritis.
## 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:** May decrease the effect of warfarin; monitor INR closely.
* **Methotrexate:** Piperacillin may decrease methotrexate clearance; monitor methotrexate levels.
## Monitoring
* Signs and symptoms of infection.
* Renal function (especially with impaired renal function or concomitant nephrotoxic agents).
* Liver function tests.
* Hematologic parameters (e.g., white blood cell count, platelet count) may be monitored, particularly with prolonged therapy.
* Signs of hypersensitivity reactions.
* For *C. difficile* infection if diarrhea develops.
## Clinical Pearls
* Piperacillin-tazobactam is typically reconstituted and further diluted for intravenous infusion over 30 minutes. Extended infusions (over 4 hours) may be considered in some cases to improve efficacy, particularly in patients with severe infections or impaired renal function, but this should be based on institutional protocols or expert recommendation.
* Consider de-escalation based on culture and sensitivity results.
* Pseudomembranous colitis due to *C. difficile* can occur.
* Potential for cross-reactivity with cephalosporin allergies.
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*This information is intended for clinical pharmacists and prescribers. Always consult the most current prescribing information and institutional guidelines for definitive guidance. Patient-specific factors must be considered.*
