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## Piperacillin/Tazobactam (Zosyn)
## Overview
Piperacillin/tazobactam is a combination of an extended-spectrum penicillin antibiotic and a beta-lactamase inhibitor. It is active against a broad spectrum of 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
## Adult Dosing
* **Standard Dosing:** 3.375 grams (3 g piperacillin/0.375 g tazobactam) intravenously every 6 hours.
* **Higher Dosing (for severe infections or specific pathogens):** 4.5 grams (4 g piperacillin/0.5 g tazobactam) intravenously every 6 or 8 hours. Dosing interval may be extended to every 8 hours for infections due to less susceptible organisms or in critically ill patients.
* **Maximum daily dose:** Generally 18 grams (13.5 g piperacillin/4.5 g tazobactam) in 24 hours, often administered as 4.5 grams every 4 hours in specific situations or continuous infusions.
* **Continuous Infusion:** Often used in critically ill patients to maintain target drug concentrations. A loading dose of 4.5 grams is typically given, followed by a continuous infusion of 2.25 grams per hour. This is a common local protocol-dependent strategy.
## Pediatric Dosing
* **For patients 2 months and older:**
* **Body weight less than 40 kg:** Dosing varies based on indication and severity of infection. Common regimens range from 90 mg piperacillin/11.25 mg tazobactam per kg per dose every 6 hours to 120 mg piperacillin/15 mg tazobactam per kg per dose every 8 hours.
* **Body weight 40 kg or greater:** Use adult dosing.
* **Neonates and infants younger than 2 months:** Dosing is not well-established and generally not recommended due to immature renal and hepatic function.
## Dose Adjustments
* **Renal Impairment (CrCl < 20 mL/min):** Reduce dose frequency. For standard 3.375 g every 6-hour dosing, administer every 8 hours. For 4.5 g every 6-hour dosing, administer every 8 hours. For 4.5 g every 8-hour dosing, administer every 12 hours. Doses should be adjusted based on the piperacillin component.
* **Hemodialysis:** Administer dose after hemodialysis and supplement with an additional dose.
* **Hepatic Impairment:** No dose adjustment is typically required, but caution is advised as severe hepatic impairment may affect piperacillin clearance.
## Contraindications
* Known history of hypersensitivity to piperacillin, tazobactam, other penicillin antibiotics, or beta-lactamase inhibitors.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, rash, headache, insomnia, fever, eosinophilia.
* **Serious:**
* **Hypersensitivity Reactions:** Anaphylaxis, urticaria, Stevens-Johnson syndrome, toxic epidermal necrolysis.
* **Clostridioides difficile-associated diarrhea.**
* **Hematologic effects:** Neutropenia, thrombocytopenia, leukopenia, anemia, coagulopathy.
* **Neurologic effects:** Seizures (more common with high doses or renal impairment).
* **Hepatic effects:** Elevated liver enzymes, cholestatic hepatitis.
* **Renal effects:** Acute kidney injury.
## Key Drug Interactions
* **Aminoglycosides:** While often used together for synergistic activity, concurrent administration may lead to inactivation of piperacillin in vitro. Separate administration if possible.
* **Probenecid:** May increase and prolong serum concentrations of piperacillin.
* **Neuromuscular Blocking Agents:** Piperacillin may prolong the action of rocuronium or vecuronium.
* **Warfarin:** May decrease the effect of warfarin, leading to increased INR. Monitor INR closely.
## Monitoring
* **Renal function:** Monitor serum creatinine and electrolytes, especially in patients with pre-existing renal disease or those receiving nephrotoxic agents.
* **Liver function tests:** Monitor AST, ALT, alkaline phosphatase, and bilirubin, particularly with prolonged therapy.
* **Hematologic parameters:** Monitor complete blood count (CBC) with differential, platelet count, and coagulation studies (PT/INR, PTT) if clinically indicated.
* **Signs and symptoms of infection:** Monitor for clinical improvement.
* **Signs and symptoms of hypersensitivity reactions.**
* **Signs and symptoms of C. difficile infection.**
## Clinical Pearls
* Piperacillin/tazobactam is a broad-spectrum agent often reserved for more serious or polymicrobial infections.
* Dosing and administration intervals are crucial, especially in renal impairment and for specific patient populations (e.g., critically ill, pediatric).
* Continuous infusion may be preferred in critically ill patients to optimize pharmacokinetic/pharmacodynamic targets and potentially reduce adverse effects.
* Due to its broad spectrum, consider de-escalation to a narrower-spectrum agent once culture and sensitivity results are available.
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*Disclaimer: This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the most current prescribing information, institutional guidelines, and a qualified healthcare provider for patient-specific treatment decisions.*
