Piperacillin Sodium + Tazobactam
**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: * **Piperacillin** is a bactericidal beta-lactam antibiotic. It binds to specific **penicillin-binding proteins (PBPs)** located inside the bacterial cell wall โ inhibits the third and last stage of bacterial cell wall synthesis โ cell lysis and death. * **Tazobactam** is a "suicide" inhibitor. It irreversibly binds to **beta-lactamases** (Richmond-Sykes types II-V) โ 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.
Dosing by species
- Single-agent therapy of intra-abdominal sepsis ยท 50 mg/kg ยท IV or IM ยท q4-6h ยท 5-7 days ยท Dose extrapolated from human dosage with limited studies in dogs or cats.
- Susceptible infections ยท 100 mg/kg ยท IM ยท q8-12h ยท Reconstitute to 200 mg/mL.
- Severe polymicrobic bacteremia ยท 100 mg/kg ยท IV ยท q6h
- Preoperative orthopedic or coelomic surgery ยท 100 mg/kg ยท IM ยท q12h
- Single-agent therapy of intra-abdominal sepsis ยท 50 mg/kg ยท IV or IM ยท q4-6h ยท 5-7 days ยท Dose extrapolated from human dosage with limited studies in dogs or cats.
- Bacterial sepsis ยท 3.375 grams (total dose per dog) IV q6h or 4.5 grams (total dose per dog) IV q8h ยท IV ยท q6h or q8h ยท 7 days ยท Total dose per dog.
- Life-threatening infections (e.g., Pseudomonas) ยท 80-100 mg/kg ยท IV ยท q8h ยท Human paediatric dose used as a guide; administer by slow IV injection/infusion.
- Life-threatening infections ยท 25-50 mg/kg ยท IV ยท q4-6h ยท Empirical dosing.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
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)
Drug interactions
- Aminoglycosides (amikacin, gentamicin, tobramycin) ยท 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.
- Anticoagulants (heparin, warfarin) ยท Piperacillin may rarely affect platelets; increased monitoring of coagulation parameters is suggested.
- Methotrexate ยท Piperacillin may increase MTX serum levels.
- Probenecid ยท Can reduce the renal tubular secretion of both piperacillin and tazobactam, maintaining higher systemic levels for a longer period.
- Vecuronium ยท Piperacillin may prolong neuromuscular blockade.
- Non-depolarizing muscle relaxants ยท Piperacillin enhances the effects of non-depolarizing muscle relaxants. ยท moderate
- Gentamicin ยท Inactivates piperacillin if mixed in the same syringe. ยท major
- Aminoglycosides ยท Synergistic bactericidal effect against pseudomonal septicaemias when administered systemically (not mixed in vitro). ยท minor
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
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.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.