Bacterial infections:

Indications for: ZOSYN 3.375g

Susceptible intra-abdominal infections (eg, appendicitis, peritonitis), moderate community-acquired pneumonia, moderate to severe nosocomial pneumonia, postpartum endometritis, pelvic inflammatory disease, skin and skin structure.

Adult Dosage:

Infuse over 30mins. Usually 3.375g every 6hrs for 7–10 days; renal impairment (CrCl 20–40mL/min): 2.25g every 6hrs; (CrCl <20mL/min): 2.25g every 8hrs; (hemodialysis or peritoneal dialysis): 2.25g every 12hrs, give additional 0.75g at end of hemodialysis. Nosocomial pneumonia (give with an aminoglycoside): 4.5g every 6hrs for 7–14 days (continue aminoglycoside for P. aeruginosa); renal impairment (CrCl 20–40mL/min): 3.375g every 6hrs; (CrCl <20mL/min): 2.25g every 6hrs; (hemodialysis or peritoneal dialysis): 2.25g every 8hrs, give additional 0.75g at end of hemodialysis.

Children Dosage:

<2 months: not established. Infuse over 30mins. Appendicitis/peritonitis: 2 months–9 months: 90mg/kg every 8hrs. ≥9 months (≤40kg): 112.5mg/kg every 8hrs; (>40kg): use Adult dose. Nosocomial pneumonia: 2 months–9 months: 90mg/kg every 6hrs. ≥9 months (≤40kg): 112.5mg/kg every 6hrs; (>40kg): use Adult dose. Both: renal impairment: not determined.

ZOSYN 3.375g Contraindications:

Penicillin, cephalosporin, or β-lactamase inhibitor allergy.

ZOSYN 3.375g Warnings/Precautions:

Discontinue if hypersensitivity occurs or severe skin reactions (eg, Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS) progress; monitor closely. Neuromuscular excitability or convulsions: monitor closely (esp. in renal impairment or seizure disorders). Nephrotoxicity in critically ill patients: consider alternative treatments; if inadequate or unavailable, monitor renal function. Cystic fibrosis (increased fever/rash risk). Renal impairment. Monitor electrolytes, hematopoiesis (esp. with prolonged therapy); discontinue if bleeding disorders occur. Elderly. Pregnancy. Nursing mothers.

ZOSYN 3.375g Classification:

Broad-spectrum penicillin + β-lactamase inhibitor.

ZOSYN 3.375g Interactions:

Potentiated by probenecid; do not coadminister unless benefit outweighs the risk. May antagonize aminoglycosides (eg, tobramycin); monitor. May potentiate non-depolarizing neuromuscular blockers (eg, vecuronium); monitor. Monitor methotrexate, heparin, anticoagulants. Monitor renal function with concomitant vancomycin. May cause false (+) Clinitest, Coomb's or Bio-Rad Aspergillus EIA test.

Adverse Reactions:

Diarrhea, constipation, nausea, headache, insomnia; rash (may be severe), pruritus, local reactions, C. difficile-associated diarrhea, hemophagocytic lymphohistiocytosis (discontinue if suspected); rare: bleeding.


  • Piperacillin is metabolized to a minor microbiologically active desethyl metabolite. Tazobactam is metabolized to a single metabolite that lacks pharmacological and antibacterial activities.

Drug Elimination:

Renal. Half-life: 0.7–1.2 hours.

Generic Drug Availability:


How Supplied:

Single-dose vials (2.25g, 3.375g)—24; (4.5g)—12