MEROPENEM
Clinical safety rating: safe
Valproic acid levels may be significantly reduced Can cause seizures and hypersensitivity reactions.
Meropenem inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), specifically PBP 2 and PBP 3, leading to cell death.
| Metabolism | Meropenem is primarily metabolized by hydrolysis of the beta-lactam ring, with minimal hepatic metabolism. It is not metabolized by cytochrome P450 enzymes. |
| Excretion | Renal: 70% unchanged via glomerular filtration and tubular secretion. Biliary: <2% excreted in bile. Fecal: ~2%. |
| Half-life | 1.0-1.5 hours in adults with normal renal function; prolonged to 4-6 hours in moderate renal impairment (CrCl 10-50 mL/min) and up to 7-10 hours in severe renal impairment (CrCl <10 mL/min). |
| Protein binding | ~2% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | 0.25-0.35 L/kg, approximating extracellular fluid volume; higher in critically ill patients (up to 0.5 L/kg). |
| Bioavailability | IV only (100% bioavailability); not orally absorbed. |
| Onset of Action | IV: Rapid, within 30 minutes of infusion initiation. |
| Duration of Action | Dosing interval typically 6-8 hours in normal renal function; longer intervals (e.g., 12-24 hours) for renal impairment. |
| Molecular Weight | 383.46 |
1-2 g IV every 8 hours, infused over 15-30 minutes; typical dose 1 g q8h for complicated infections. Extended infusion over 3 hours may be used for resistant organisms.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 26-50 mL/min: 1 g q12h; CrCl 10-25 mL/min: 500 mg q12h; CrCl <10 mL/min: 500 mg q24h; intermittent hemodialysis: 500 mg after dialysis, then 500 mg q24h; continuous renal replacement therapy: 1 g q8-12h. |
| Liver impairment | No dose adjustment required for hepatic impairment; meropenem is minimally hepatically metabolized. |
| Pediatric use | 3 months to 16 years: 20 mg/kg IV every 8 hours, max 1 g per dose; for meningitis or severe infections: 40 mg/kg IV every 8 hours, max 2 g per dose. Dosing based on actual body weight. |
| Geriatric use | Base dosing on renal function; elderly patients often have reduced CrCl; calculate CrCl and adjust per renal adjustment guidelines. No specific dose adjustment beyond renal considerations. |
| 1st trimester | Meropenem crosses the placenta; animal studies show no evidence of teratogenicity, but human data are limited; use only if clearly needed. |
| 2nd trimester | No known fetal risks; consider as alternative to cephalosporins or penicillins when indicated. |
| 3rd trimester | Safe for use; no known adverse effects near term. |
Clinical note
Valproic acid levels may be significantly reduced Can cause seizures and hypersensitivity reactions.
| FDA category | Animal |
| Placental transfer | Meropenem crosses the placenta readily with cord blood concentrations reaching 50-100% of maternal serum levels. |
| Breastfeeding |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | Diarrhea |
| Serious Effects |
Hypersensitivity to meropenem or other beta-lactam antibioticsHypersensitivity to other carbapenems
| Precautions | Hypersensitivity reactions, including anaphylaxis, Seizures and other CNS adverse reactions, especially in patients with renal impairment or CNS disorders, Clostridium difficile-associated diarrhea, Development of drug-resistant bacteria, Thrombocytopenia and other bleeding abnormalities in patients with renal impairment, Concomitant use with valproic acid may decrease valproic acid levels |
| Food/Dietary | No clinically significant food interactions. Avoid alcohol during treatment due to potential disulfiram-like reaction (though rare with meropenem). |
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| Meropenem is excreted into human milk in low concentrations (approximately 0.05% of maternal dose); unlikely to cause adverse effects in nursing infants. Use with caution in infants with impaired renal function or allergy to beta-lactams. |
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Meropenem is classified as FDA Pregnancy Category B. Animal studies have not demonstrated teratogenic effects. There are no adequate and well-controlled studies in pregnant women. Use during pregnancy only if clearly needed. First trimester: No known teratogenic risk. Second and third trimesters: No known fetal risks have been reported; however, human data are limited. |
| Fetal Monitoring | Monitor for maternal adverse effects such as infusion site reactions, rash, diarrhea, and hypersensitivity reactions. No specific fetal monitoring is required, but routine obstetric monitoring is recommended. Assess renal function periodically as meropenem is renally excreted. |
| Fertility Effects | Animal studies have not shown impairment of fertility. There are no human data regarding effects on fertility. Meropenem is unlikely to adversely affect reproductive function at therapeutic doses. |
| Clinical Pearls | Meropenem is a carbapenem with broad-spectrum activity including Gram-positive, Gram-negative, and anaerobic bacteria. It is stable against ESBL-producing organisms. Dose adjustment required for creatinine clearance <50 mL/min. Prolonged infusion (3-4 hours) may improve outcomes in critically ill patients. Monitor for seizures in patients with CNS disorders or renal impairment. Avoid use in patients with known hypersensitivity to carbapenems or beta-lactams. |
| Patient Advice | Take this medication exactly as prescribed, even if you feel better. · Meropenem is given intravenously by a healthcare professional; do not try to self-administer. · Report any signs of allergic reaction (rash, itching, swelling, difficulty breathing) immediately. · Inform your doctor if you have a history of seizures, kidney disease, or allergies to antibiotics. · This medication may cause diarrhea; notify your doctor if it becomes severe or watery. · Avoid alcohol consumption during treatment to prevent potential side effects. |