Piperacillin Sodium
Piperacillin is an **extended-spectrum acylaminopenicillin** antibiotic used primarily for severe or resistant bacterial infections. * **Broad Spectrum**: It offers expanded coverage against many aerobic and anaerobic gram-positive and gram-negative bacteria, notably including many strains of **Pseudomonas aeruginosa** and the family *Enterobacteriaceae*. * **Clinical Use**: While veterinary experience is somewhat limited, it is highly valuable for empiric therapy in critically ill patients pending culture and susceptibility results, or for surgical prophylaxis involving mixed aerobic/anaerobic or gram-negative contamination. * **Beta-Lactamase Susceptibility**: Like other aminopenicillins, piperacillin alone is susceptible to destruction by beta-lactamase enzymes. It is frequently combined with a beta-lactamase inhibitor (like tazobactam) to overcome this resistance. * **Administration**: It is not absorbed orally and must be administered parenterally (IV, IM, or SC).
Mechanism: Piperacillin is a **bactericidal** time-dependent antibiotic. * It binds to specific **Penicillin-Binding Proteins (PBPs)** (especially PBP-3) located inside the bacterial cell wall. * Binding to PBPs โ inhibition of the third and final stage of bacterial cell wall synthesis (cross-linking of **peptidoglycan** strands). * This weakens the cell wall โ activation of bacterial autolysins โ **cell lysis and death**. * *Note*: Its efficacy is highly dependent on the amount of time the drug concentration remains above the Minimum Inhibitory Concentration (MIC) of the target pathogen.
Dosing by species
- For bacteremia with or without endocarditis ยท 30 mg/kg IV q6h for 7-14 days ยท IV ยท q6h ยท 7-14 days
- For respiratory infections ยท 25-50 mg/kg IV q8h ยท IV ยท q8h
- For susceptible infections ยท 15-50 mg/kg IV or IM q6-12h ยท IV/IM ยท q6-12h
- For Bordetella avium infections ยท 150 mg/kg IM q8-12h ยท IM ยท q8-12h ยท minimum treatment period is two weeks
- For susceptible infections ยท 100 mg/kg IM two to three times daily ยท IM ยท BID-TID
- For empirical treatment in Psittacines of gram-negative bacterial infections ยท 100 mg/kg IM 3-4 times a day if immunocompetent; 4 times a day if immunocompromised ยท IM ยท TID-QID
- For bacteremia with or without endocarditis ยท 30 mg/kg IV q6h for 7-14 days ยท IV ยท q6h ยท 7-14 days
- For respiratory infections ยท 25-50 mg/kg IV q8h ยท IV ยท q8h
- For systemic treatment of otitis media or proliferative otitis externa complicated by gram-negative (especially Pseudomonas) bacteria ยท 20 mg/kg SC three times daily ยท SC ยท TID
Routes of administration
Contraindications
- Patients with documented hypersensitivity to beta-lactam antibiotics (penicillins, cephalosporins)
Adverse effects
- Hypersensitivity reactions (allergic reactions)
- Local tissue irritation, pain at IM injection site
- Thrombophlebitis (with IV administration)
- Antibiotic-associated diarrhea (due to alterations in gut flora)
- Coagulation abnormalities (rare, mostly in renal failure)
- Neurotoxicity/seizures (at very high doses or in renal impairment)
- Clostridium difficile superinfections (rare)
Drug interactions
- Aminoglycosides (amikacin, gentamicin, tobramycin) ยท Synergistic against certain bacteria in vitro, but penicillins can chemically inactivate aminoglycosides in vivo (especially in renal failure or at massive doses). Do not mix in the same syringe/bag.
- Anticoagulants (heparin, warfarin) ยท Piperacillin may rarely affect platelets; increased monitoring of coagulation parameters is suggested.
- Methotrexate ยท Piperacillin may increase methotrexate serum levels.
- Probenecid ยท Reduces renal tubular secretion of piperacillin, maintaining higher systemic levels for longer periods.
- Vecuronium ยท Piperacillin may prolong neuromuscular blockade.
Monitoring
- Clinical efficacy (resolution of clinical signs, fever)
- White blood cell count (WBC)
- Renal function (if prolonged use or pre-existing impairment)
- Coagulation parameters (if on concurrent anticoagulants or high doses)
Overdose
Single overdoses are unlikely to pose much risk. * **Massive Overdoses**: May cause vomiting, diarrhea, or neurotoxicity (seizures). * **Chronic High Doses**: Dogs receiving up to 800 mg/kg/day of piperacillin/tazobactam for 6 months demonstrated no serious toxic effects. Doses โฅ400 mg/kg/day caused transient liver effects (glycogen granules in cytoplasm, increased smooth endoplasmic reticulum) that mostly reversed after one month. * **Treatment**: Supportive care. Monitor renal and neurological status.
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.