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# Piperacillin-Tazobactam
## Overview
A fixed-combination injectable antibiotic consisting of an extended-spectrum penicillin (piperacillin) and a beta-lactamase inhibitor (tazobactam). It provides coverage against many Gram-positive, Gram-negative, and anaerobic organisms, including *Pseudomonas aeruginosa*.
## Primary Indications
* Intra-abdominal infections (e.g., appendicitis, peritonitis)
* Nosocomial and ventilator-associated pneumonia
* Skin and skin structure infections
* Gynecologic infections (e.g., endometritis)
* Febrile neutropenia (in combination with other agents)
## Adult Dosing
* **Standard dosing:** 3.375 g (3 g piperacillin / 0.375 g tazobactam) IV every 6 hours.
* **Severe infections (including *Pseudomonas*):** 4.5 g (4 g piperacillin / 0.5 g tazobactam) IV every 6 hours.
* **Infusion time:** Standard infusion is over 30 minutes; extended or continuous infusions (e.g., 4-hour infusion) are commonly used in critical care settings to optimize pharmacodynamics.
## Pediatric Dosing
Dosing is highly protocol-dependent.
* **Neonates/Infants < 9 months:** Typically 80 mg/kg/dose (piperacillin component) every 8 hours.
* **Children 9 months and older:** Typically 100 mg/kg/dose (piperacillin component) every 8 hours for intra-abdominal infections.
* **Maximum:** Do not exceed adult maximums. Consult institutional antibiogram and pediatric infectious disease protocols.
## Dose Adjustments
* **Renal Impairment:** Adjust dose for CrCl ≤ 40 mL/min. Specific dosing tables vary significantly by renal function; consult institutional guidelines for exact titration (e.g., CrCl 20-40 mL/min might require 2.25 g every 6 hours).
* **Hemodialysis:** Requires supplemental dosing post-dialysis due to drug removal.
## Contraindications
* Known hypersensitivity to piperacillin, tazobactam, or any beta-lactam antibiotic (penicillins, cephalosporins).
* History of severe allergic reactions (anaphylaxis) to any beta-lactam.
## Adverse Effects
* **Common:** Diarrhea, constipation, nausea, headache, insomnia.
* **Serious:** *Clostridioides difficile*-associated diarrhea (CDAD), severe hypersensitivity reactions (DRESS, SJS/TEN), thrombocytopenia, leukopenia (long-term use), and electrolyte disturbances (hypernatremia due to high sodium content).
## Key Drug Interactions
* **Methotrexate:** Penicillins may reduce renal clearance, increasing risk of toxicity.
* **Aminoglycosides:** Inactivation of aminoglycosides can occur if physically mixed; administer at least 1 hour apart.
* **Warfarin:** Theoretical increased risk of bleeding due to modulation of gut flora or platelet inhibition.
* **Probenecid:** Increases serum concentrations of piperacillin by inhibiting renal elimination.
## Monitoring
* **Renal function:** Serum creatinine at baseline and during therapy.
* **Hematology:** CBC with differential (monitor for leukopenia/neutropenia if therapy exceeds 10 days).
* **Clinical:** Signs of allergic reaction, *C. difficile* symptoms (diarrhea), and resolution of infection symptoms.
* **Electrolytes:** Periodic monitoring, especially regarding sodium load.
## Clinical Pearls
* **Sodium Content:** Each 4.5 g dose contains approximately 11.8 mEq (271 mg) of sodium; use caution in patients on sodium-restricted diets or with heart failure.
* **Spectrum:** Does not provide reliable coverage against MRSA, extended-spectrum beta-lactamase (ESBL) producers (though sometimes effective against specific isolates), or carbapenem-resistant Enterobacteriaceae (CRE).
* **Stability:** Ensure compatibility with IV fluids; it is incompatible with lactated Ringer’s solution.
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**Educational Disclaimer:** This information is for educational purposes only. Always verify dosing, compatibility, and safety information with your institution's current prescribing guidelines, current local antibiogram, and official FDA-approved package inserts before clinical application.
