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# Piperacillin-Tazobactam (Zosyn)
## Overview
A fixed-dose parenteral combination of a ureidopenicillin (piperacillin) and a beta-lactamase inhibitor (tazobactam). It provides expansive coverage including *Pseudomonas aeruginosa* and various anaerobes.
## Primary Indications
* Hospital-acquired and ventilator-associated pneumonia.
* Intra-abdominal infections.
* Complicated skin and skin structure infections.
* Febrile neutropenia (empiric).
* Complicated urinary tract infections (pyelonephritis).
## Adult Dosing
* **Standard:** 3.375 g (3 g piperacillin / 0.375 g tazobactam) IV every 6 hours.
* **Severe/Pseudomonal Infections:** 4.5 g (4 g piperacillin / 0.5 g tazobactam) IV every 6 hours.
* **Method:** Administer via prolonged infusion (over 4 hours) in critically ill patients to optimize pharmacodynamic target attainment.
## Pediatric Dosing
* **Neonatal (≤ 7 days):** 80 mg/kg/day (piperacillin component) divided every 12 hours.
* **Neonatal (> 7 days):** 120-160 mg/kg/day divided every 8 hours.
* **Pediatric (≥ 9 months):** 240–300 mg/kg/day (piperacillin component) divided every 6–8 hours.
* *Note: Dosing varies significantly by institutional protocol; follow local guidelines for specific pediatric weight-based tiers.*
## Dose Adjustments
* **Renal Impairment:** Requires dose reduction or extended dosing intervals based on Creatinine Clearance (CrCl).
* CrCl 20–40 mL/min: 2.25 g q6h.
* CrCl < 20 mL/min: 2.25 g q8h or 2.25 g q12h depending on clinical severity.
* **Hepatic:** No adjustment required.
## Contraindications
* History of severe hypersensitivity (e.g., anaphylaxis, DRESS, SJS/TEN) to piperacillin, tazobactam, or any beta-lactam antibiotic.
## Adverse Effects
* **Common:** Diarrhea, headache, constipation, insomnia.
* **Serious:** *Clostridioides difficile*-associated diarrhea (CDAD), neutropenia (thrombocytopenia/leukopenia with prolonged use), hypersensitivity reactions, seizures (rare, mostly in setting of renal failure/high doses).
## Key Drug Interactions
* **Methotrexate:** Increased plasma levels due to decreased renal tubular secretion.
* **Aminoglycosides:** Potential for chemical inactivation if mixed in the same IV line.
* **Anticoagulants (Warfarin/Heparin):** Potential synergistic inhibition of platelet aggregation; monitor coagulation parameters.
## Monitoring
* **Renal:** Serum creatinine, urine output.
* **Hematologic:** CBC with differential (if therapy duration > 7 days to monitor for leukopenia).
* **Infection:** Fever curve, white cell count, clinical signs of resolution.
* **Safety:** Monitor for signs of rash, allergy, or diarrhea indicating *C. difficile*.
## Clinical Pearls
* **Spectrum:** Does not cover MRSA, VRE, or carbapenem-resistant Enterobacterales (CRE).
* **Safety:** High sodium content (approx. 2.79 mEq of Na+ per gram of piperacillin); monitor in sodium-restricted patients.
* **Stability:** Once reconstituted, stability varies; ensure adherence to local pharmacy standards for IV bag storage.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice and dosing guidance may change based on emerging data and institutional protocols. Always verify current prescribing information, local antibiograms, and clinical guidelines with your pharmacy department or electronic health record system before prescribing.
