Generic Name

Ertapenem

Mechanism

• Inhibition of penicillin‑binding proteins (PBPs) in bacterial cell walls, preventing cross‑linking of peptidoglycan strands and leading to cell lysis.
• Highly potent against *Enterobacteriaceae*, *Staphylococcus aureus* (including MRSA), *Bacteroides fragilis*, and *Clostridioides difficile*.
• Unlike other carbapenems, lacks activity against Enterococcus spp. due to rapid β‑lactamase hydrolysis.

Pharmacokinetics

Indications

• Pelvic inflammatory disease (outpatient or inpatient).
• Complicated intra‑abdominal infections (e.g., peritonitis, appendicitis).
• Ventilator‑associated pneumonia and other hospitals’ *medically‑important* *Gram‑negative* infections.
• Skin and soft‑tissue infections (including necrotizing fasciitis when combined with other agents).
• Bone and joint infections (often as part of combination therapy).

Contraindications

• Immediate hypersensitivity to carbapenems or penicillins.
• Severe renal impairment (eGFR <15 mL/min) — requires dose reduction or avoidance.
• History of neurotoxicity (seizures, encephalopathy) — use with caution in elderly or hepatic dysfunction.
• Pregnancy: Category B; no proven risk but limited data.
• New‑borns: use only after 24 h of life due to immature renal clearance.

Warnings
• Risk of *Candida* overgrowth (superinfection) with prolonged therapy.
• Occasional cross‑reactivity with other β‑lactams; consider patch or graded challenge for penicillin allergy evaluation.

Dosing

• Adult dose: 1 g IV or IM once daily.
• Renal adjustment:
• CrCl 30–49 mL/min: 500 mg IV/IM once daily.
• CrCl <30 mL/min: 500 mg IV/IM every 48 h.
• Pediatric dose: 40 mg/kg IV/IM (max 1 g) once daily; adjust for renal function.
• Infusion time: 30‑60 min; can be extended to 90‑120 min if infusion reactions occur.
• Combination: Often paired with a β‑lactamase inhibitor (e.g., ampicillin‑sulbactam) or a cephalosporin against Enterococcus when required.

Monitoring

• Renal function: BUN/Creatinine, eGFR at baseline and every 2–3 days during long therapy.
• Neurologic: Evaluate for new seizures or CNS symptoms, particularly in CKD patients.
• Complete blood count: monitor for cytopenias when on prolonged treatment.
• Drug levels: not routine; use therapeutic drug monitoring only in special populations (pediatric, neonates, severe renal disease).

Clinical Pearls

• Once‑daily convenience lets *Ertapenem* bridge inpatient and outpatient therapy, improving compliance and reducing pharmacy burden.
• High anaerobic coverage makes it ideal for complex intra‑abdominal or pelvic infections where *Bacteroides* spp. are common.
• No activity against Enterococcus – remember to add an enterococcus‑active agent if that pathogen is suspected or proven.
• Overlap with other carbapenems: cross‑resistance may occur; choose *Ertapenem* when you want to avoid broader spectrum agents to preserve carbapenem efficacy.
• Infusion reaction mitigation: rate‑slow infusion or pretreatment with antihistamine/alcohol‑based skin prep can reduce hypersensitivity manifestations.
• Cost‑effectiveness: despite higher upfront cost, the single‑daily dose reduces infusion room time and nursing workload, making it a budget‑friendly option for many hospitals.

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• For detailed prescribing charts, see your institution’s formulary or the FDA label.