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).
Mecanismo: 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 → inhibition of the third and final stage of bacterial cell wall synthesis (cross-linking of **peptidoglycan** strands). * This weakens the cell wall → activation of bacterial autolysins → **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.
Dosificación por especie
- For bacteremia with or without endocarditis · 30 mg/kg IV q6h for 7-14 days · IV · q6h · 7-14 days
- For respiratory infections · 25-50 mg/kg IV q8h · IV · q8h
- For susceptible infections · 15-50 mg/kg IV or IM q6-12h · IV/IM · q6-12h
- For Bordetella avium infections · 150 mg/kg IM q8-12h · IM · q8-12h · minimum treatment period is two weeks
- For susceptible infections · 100 mg/kg IM two to three times daily · IM · BID-TID
- For empirical treatment in Psittacines of gram-negative bacterial infections · 100 mg/kg IM 3-4 times a day if immunocompetent; 4 times a day if immunocompromised · IM · TID-QID
- For bacteremia with or without endocarditis · 30 mg/kg IV q6h for 7-14 days · IV · q6h · 7-14 days
- For respiratory infections · 25-50 mg/kg IV q8h · IV · q8h
- For systemic treatment of otitis media or proliferative otitis externa complicated by gram-negative (especially Pseudomonas) bacteria · 20 mg/kg SC three times daily · SC · TID
Vías de administración
Contraindicaciones
- Patients with documented hypersensitivity to beta-lactam antibiotics (penicillins, cephalosporins)
Efectos adversos
- 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)
Interacciones farmacológicas
- Aminoglycosides (amikacin, gentamicin, tobramycin) · 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) · Piperacillin may rarely affect platelets; increased monitoring of coagulation parameters is suggested.
- Methotrexate · Piperacillin may increase methotrexate serum levels.
- Probenecid · Reduces renal tubular secretion of piperacillin, maintaining higher systemic levels for longer periods.
- Vecuronium · Piperacillin may prolong neuromuscular blockade.
Monitorización
- 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)
Sobredosis
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 ≥400 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.
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