Antibiotic · Beta-lactam · Carbapenem
Meropenem (Merrem)
Also called Merrem
Indications
- Complicated skin and skin-structure infection, adults and children 3 months and up (label)
- Complicated intra-abdominal infection (label)
- Bacterial meningitis in children 3 months and up (label); adult and post-neurosurgical meningitis off-label
- ESBL-producing E. coli or Klebsiella bacteremia, where it beat piperacillin-tazobactam on 30-day mortality (MERINO 2018; off-label)
- Empiric sepsis, hospital-acquired pneumonia and febrile neutropenia when resistant gram-negatives are likely (off-label)
Dosing
| Where | Dose |
|---|---|
| Antimicrobials | Meropenem: Reduce at CrCl 50 or less |
On the quick cards
- Sepsis, source unknownEmpiric Antibiotics: Broad coverage until the source declares itself
- AntimicrobialsRenal Dosing: Adjust, or no change
Mechanism of action
Meropenem is a carbapenem that binds penicillin-binding proteins, mainly PBPs 2, 3 and 4 in E. coli and Pseudomonas and PBPs 1, 2 and 4 in S. aureus (label), blocking peptidoglycan cross-linking so the cell wall fails. Its trans-hydroxyethyl side chain makes it stable to most beta-lactamases, including ESBLs and AmpC, and its 1-β-methyl group protects it from renal dehydropeptidase-I, so unlike imipenem it needs no cilastatin. Resistance comes from porin loss, efflux pumps, altered PBPs and carbapenemases (label).
Pharmacology
- Infectious: broad gram-negative activity including Pseudomonas, plus anaerobes and MSSA; no activity against MRSA (label)
- CNS: seizures in 0.7% of 2,904 adults, all with risk factors; risk is higher with CNS disease, meningitis or renal impairment (label)
- GI: diarrhea 4.8%, nausea and vomiting 3.6% (label); C. difficile
- Hematologic: thrombocytopenia in renal impairment, without reported bleeding (label)
- Skin and CNS: rash 1.9%, headache 2.3% (label)
Pharmacokinetics
| Peak | About 49 mcg/mL after 1 g over 30 min (label) |
|---|---|
| Half-life | About 1 h (label) |
| Protein binding | About 2% (label) |
| Metabolism | About 28% to an inactive metabolite (label) |
| Elimination | About 70% unchanged in urine within 12 h; feces 2% (label) |
| Renal dosing | CrCl 26–50: every 12 h; 10–25: half dose every 12 h; under 10: half dose every 24 h (label) |
| Dialysis | Removed by hemodialysis (label) |
| Infusion | 15–30 min, or 1 g as a 3–5 min bolus (label); extended infusion off-label |
Chemistry
- A 1-β-methyl carbapenem with a dimethylcarbamoyl-pyrrolidinylthio side chain; C₁₇H₂₅N₃O₅S·3H₂O, MW 437.52 as the trihydrate (label)
- White to pale yellow crystalline powder; sodium 3.92 mEq per gram; reconstituted pH 7.3–8.3 (label)
Adverse effects and cautions
In the one-pagers
- Meningitis and EncephalitisEmpiric antibiotics and dexamethasone: Neurosurgery, EVD, shunt, penetrating trauma: Vancomycin + cefepime, ceftazidime or meropenem 2 g q8h
- Neuro: ICP and StrokeEVD management: leveling, drainage, clamping, infection: Ventriculitis complicates roughly 5–10% of drains; risk rises with IVH or SAH, CSF leak, frequent access and days in place. The NCS 2016 EVD consensus recommends antimicrobial-impregnated catheters, one periprocedural antibiotic dose rather than continuous prophylaxis, CSF sampling only when clinically indicated, and no routine catheter exch
- Oncologic EmergenciesNeutropenic fever: Antipseudomonal β-lactam within 60 min of triage (ASCO/IDSA 2018): cefepime, piperacillin-tazobactam or meropenem
- Sepsis and Septic Shock BundleHour-1 bundle element by element: Underfilled bottles are the commonest cause of false-negative cultures. Give the beta-lactam first: cefepime and meropenem can be pushed over 3–5 min where policy allows, while vancomycin runs 1–2 h. Loading doses are full regardless of renal function because sepsis expands the volume of distribution. Epinephrine, metformin, liver failure and seizures raise lactat
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Sources
- FDA label: Meropenem for Injection (Hospira, 2022)
- Harris 2018 (MERINO trial)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.