Generic Names and Clinical Uses
Piperacillin-tazobactam and imipenem-cilastatin are already the generic names of these combination antibiotics—they are not brand names requiring translation to generic equivalents.
Piperacillin-Tazobactam
Piperacillin-tazobactam is a beta-lactam/beta-lactamase inhibitor combination consisting of piperacillin (a penicillin-class antibacterial) and tazobactam (a beta-lactamase inhibitor) 1.
FDA-Approved Indications
- Intra-abdominal infections in adults and pediatric patients ≥2 months of age 1
- Nosocomial pneumonia in adults and pediatric patients ≥2 months of age 1
- Skin and skin structure infections in adults 1
- Female pelvic infections in adults 1
- Community-acquired pneumonia in adults 1
Guideline-Recommended Uses
- Febrile neutropenia: Selected as first-choice option for all patients except ambulatory low-risk cases, supported by all clinical practice guidelines for both adults and children 2
- Necrotizing fasciitis: Recommended in combination with vancomycin or linezolid 2
- Diabetic foot infections (moderate to severe): Recommended for empiric therapy, particularly for infections with Pseudomonas aeruginosa risk 2
- Healthcare-associated intra-abdominal infections: Recommended for non-critically ill patients at 4.5 g every 6 hours 2
- Carbapenem-resistant Pseudomonas aeruginosa: Recommended at 3-4 g IV every 6 hours when susceptible 2
Imipenem-Cilastatin
Imipenem-cilastatin is a combination of imipenem (a carbapenem antibacterial) and cilastatin (a renal dehydropeptidase inhibitor that prevents renal metabolism of imipenem) 3.
FDA-Approved Indications
- Lower respiratory tract infections 3
- Urinary tract infections 3
- Intra-abdominal infections 3
- Gynecologic infections 3
- Bacterial septicemia 3
- Bone and joint infections 3
- Skin and skin structure infections 3
- Endocarditis 3
Critical Limitations
- NOT indicated for meningitis due to lack of established safety and efficacy 3
- NOT recommended in pediatric patients with CNS infections due to seizure risk 3
- NOT recommended in pediatric patients <30 kg with impaired renal function 3
Guideline-Recommended Uses
- Healthcare-associated intra-abdominal infections: Recommended for critically ill patients at 1 g every 8 hours 2
- Diabetic foot infections (moderate to severe): Listed as alternative for ischemic limb/necrosis/gas-forming infections 2
- Complicated intra-abdominal infections (severe): Recommended as single-drug regimen for incisional surgical site infections 2
Important Clinical Considerations
The WHO Working Group considered imipenem-cilastatin redundant because meropenem was included and is recommended for many other infections 2. This reflects the general preference for meropenem over imipenem in modern practice due to better tolerability and similar efficacy.
For Pseudomonas aeruginosa pneumonia specifically, piperacillin-tazobactam demonstrates superior clinical efficacy compared to imipenem-cilastatin (10% vs 50% clinical failure rate, P=0.004), primarily due to reduced development of microbiological resistance 4.
Both agents require dose adjustment for renal impairment, with imipenem-cilastatin contraindicated in patients with creatinine clearance <15 mL/min unless hemodialysis is instituted within 48 hours 3.
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