Piperacillin Sodium + Tazobactam
Piperacillin sodium/tazobactam sodium
Also known as: Zosyn · Tazocin · CL 298741 · YTR 830H · piperacillinum · BL-P 1908 · Cl 867 · CL 227193 · T 12220 · TA 058 · Pip-Tazo · Piperacillin sodium · Tazobactam sodium
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Single-agent therapy of intra-abdominal sepsis | 50 mg/kg | IV or IM | q4-6h | 5-7 days | 🌎 NA |
| Bacterial sepsis | 3.375 grams (total dose per dog) IV q6h or 4.5 grams (total dose per dog) IV q8h | IV | q6h or q8h | 7 days | 🌎 NA |
| Life-threatening infections (e.g., Pseudomonas) | 80-100 mg/kg | IV | q8h | — | 🌍 EU |
| Life-threatening infections | 25-50 mg/kg | IV | q4-6h | — | 🌍 EU |
- Single-agent therapy of intra-abdominal sepsis: Dose extrapolated from human dosage with limited studies in dogs or cats.
- Bacterial sepsis: Total dose per dog.
- Life-threatening infections (e.g., Pseudomonas): Human paediatric dose used as a guide; administer by slow IV injection/infusion.
- Life-threatening infections: Empirical dosing.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Single-agent therapy of intra-abdominal sepsis | 50 mg/kg | IV or IM | q4-6h | 5-7 days | 🌎 NA |
- Single-agent therapy of intra-abdominal sepsis: Dose extrapolated from human dosage with limited studies in dogs or cats.
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 100 mg/kg | IM | q8-12h | — | 🌎 NA |
| Severe polymicrobic bacteremia | 100 mg/kg | IV | q6h | — | 🌎 NA |
| Preoperative orthopedic or coelomic surgery | 100 mg/kg | IM | q12h | — | 🌎 NA |
- Susceptible infections: Reconstitute to 200 mg/mL.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Piperacillin/Tazobactam is a powerful, extended-spectrum, antipseudomonal penicillin combined with a beta-lactamase inhibitor.
- Broad Spectrum: Offers expanded coverage against many gram-positive, gram-negative, and anaerobic bacteria, including Pseudomonas aeruginosa.
- Clinical Use: Often reserved for severe, life-threatening infections, empiric therapy pending culture results, or surgical prophylaxis involving mixed aerobic/anaerobic infections.
- Veterinary Context: While experience is limited compared to human medicine, it is considered quite safe and highly effective for intra-abdominal sepsis and severe bacteremia.
Mechanism of action
- Piperacillin is a bactericidal beta-lactam antibiotic. It binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall → inhibits the third and last stage of bacterial cell wall synthesis → cell lysis and death.
- Tazobactam is a "suicide" inhibitor. It irreversibly binds to beta-lactamases (Richmond-Sykes types II-V) → prevents these enzymes from hydrolyzing the beta-lactam ring of piperacillin.
- Synergy: Tazobactam itself has minimal antibacterial activity, but its combination with piperacillin restores and expands piperacillin's efficacy against beta-lactamase-producing organisms.
Safety & warnings
Contraindications
- Patients with documented hypersensitive reactions to a beta-lactam or beta-lactamase inhibitor
- Known hypersensitivity to penicillins or cephalosporins
Adverse effects
- Hypersensitivity reactions
- Local effects (thrombophlebitis) associated with IV injection
- Antibiotic-associated diarrhea (alterations in gut flora)
- Coagulation abnormalities (rare, particularly in renal failure)
- Neurotoxicity/seizures (at very high doses, especially with diminished renal function)
- Clostridium difficile superinfections (rare)
- Nausea
- Diarrhoea
- Skin rashes
- Pain on intramuscular injection
- Sodium overload (in susceptible patients)
Precautions
High Sodium Content: High dosages may adversely affect patients with cardiac failure or hypernatremic conditions.
- Renal Impairment: Dosage adjustment may be required in patients with significantly decreased renal function (CrCl <40 mL/min).
- Laboratory Interference: May cause false-positive results for urine glucose (cupric sulfate methods like Clinitest), direct antiglobulin (Coombs') tests, and urine protein (sulfosalicylic acid, boiling, nitric acid, or acetic acid tests). May also falsely decrease aminoglycoside serum quantitative analysis if samples are stored prior to analysis.
Drug interactions
Synergistic or additive activity against certain bacteria. However, penicillins can inactivate aminoglycosides in vitro and in vivo in patients in renal failure or at massive dosages. Amikacin is the most resistant to this inactivation.
Piperacillin may rarely affect platelets; increased monitoring of coagulation parameters is suggested.
Piperacillin may increase MTX serum levels.
Can reduce the renal tubular secretion of both piperacillin and tazobactam, maintaining higher systemic levels for a longer period.
Piperacillin may prolong neuromuscular blockade.
Piperacillin enhances the effects of non-depolarizing muscle relaxants.
Inactivates piperacillin if mixed in the same syringe.
Synergistic bactericidal effect against pseudomonal septicaemias when administered systemically (not mixed in vitro).
Monitoring
- Efficacy for the infection treated (CBC, clinical signs, etc.)
- Coagulation parameters (if patient is concurrently on anticoagulants)
- Clinical efficacy
- Culture and sensitivity results
- Renal function
- Electrolytes (specifically sodium) in patients with cardiac or renal impairment
Pharmacokinetics
Absorption
Time-dependent antibiotic. Must be administered parenterally.
Distribution
Piperacillin is distributed in milk in low concentrations. It is not known if tazobactam enters milk.
Metabolism
Piperacillin inhibits the excretion of the tazobactam component in the dog.
Elimination
In dogs, piperacillin reduced the renal clearance of tazobactam, presumably due to competition for tubular secretion.
Overdose
Single overdoses are unlikely to pose much risk, although very large overdoses may cause vomiting, diarrhea, or neurotoxicity.
- Toxicity Studies: Dogs receiving up to 800 mg/kg/day of piperacillin/tazobactam for 6 months demonstrated no serious toxic effects. Doses at 400 mg/kg/day or greater caused some transient effects to the liver (glycogen granules in the cytoplasm and increases in smooth endoplasmic reticulum in hepatocytes) that were mostly reversed after one month.
- Treatment: Treatment for overdoses, if required, is supportive.
Available products
Formulations
- Injection (powder for solution)
- Premixed frozen containers
- 2.25 g powder for injection (2 g piperacillin sodium + 0.25 g tazobactam)
- 4.5 g powder for injection (4 g piperacillin sodium + 0.5 g tazobactam)
Human-labeled
- Piperacillin Sodium & Tazobactam Injection (powder for solution); Zosyn®: 2.25 g, 3.375 g, 4.5 g, and 40.5 g vials (preservative free)
- Premixed frozen Galaxy containers: 3.375 g/50 mL and 4.5 g/100 mL
- Tazocin 2.25 g powder for injection
- Tazocin 4.5 g powder for injection
Regulatory status
Human authorized product used off-label under the cascade. Reserved for life-threatening infections.
Human authorized product used off-label under the cascade. Reserved for life-threatening infections.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store injection vials at controlled room temperature (20-25°C). Reconstitute conventional vials with 5 mL of diluent per gram of piperacillin. Once reconstituted, use immediately. Discard after 24 hours if kept at room temperature or 48 hours if refrigerated. Do not freeze reconstituted vials. IV bags (50-150 mL) containing further diluted product are stable for up to 24 hours at room temperature and one week if refrigerated.
Client information
Note: This medication is typically reserved for hospitalized pets with severe infections.
- Administration: Given by your veterinarian as an intravenous (IV) or intramuscular (IM) injection.
- Safety: Generally very safe, but let your veterinarian know if your pet has ever had an allergic reaction to penicillin or other antibiotics.
- Side Effects: May cause mild stomach upset or diarrhea. Severe side effects are rare but can include neurological signs at extremely high doses.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.