Carbapenem antibiotic Pregnancy: eMC §4.6: adequate and well-controlled studies have not been performed in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryo-foetal development, parturition or post-natal development. Ertapenem should not be used during pregnancy unless the potential benefit outweighs the possible risk to the foetus. Ertapenem is excreted in human milk and, because of the potential for adverse reactions in the infant, mothers should not breast-feed while receiving ertapenem.

Ertapenem

Brand names: Invanz

Ertapenem is a carbapenem beta-lactam antibacterial used for serious infections including intra-abdominal, complicated urinary tract, skin and soft-tissue infections, and community-acquired pneumonia.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 1 g once daily by the intravenous route

Route: Intravenous infusion over 30 minutes

Frequency: Once daily

Max: eMC §4.2 states 1 g once a day for adults and adolescents 13 to 17 years of age; the paediatric 15 mg/kg twice-daily regimen must not exceed 1 g/day

eMC §4.2 (Ertapenem 1g Powder for Concentrate for Solution for Infusion). TREATMENT: adults and adolescents 13 to 17 years of age receive 1 g once a day intravenously. DURATION: usually 3 to 14 days, varying with the type and severity of infection and the causative pathogen(s); when clinically indicated a switch to an appropriate oral antibacterial may be made once clinical improvement has been observed. SURGICAL PROPHYLAXIS (adults): to prevent surgical site infection following elective colorectal surgery, 1 g as a single intravenous dose, completed within 1 hour prior to the surgical incision. HEPATIC IMPAIRMENT: no dosage adjustment is recommended. ELDERLY: give the recommended dose except in severe renal impairment. HAEMODIALYSIS: there are inadequate data on safety and efficacy in patients on haemodialysis to support a dose recommendation, so ertapenem should not be used in these patients (eMC). SUB-OPTIMAL EXPOSURE: in the few cases of surgical interventions exceeding 4 hours it cannot be excluded that patients are exposed to sub-optimal ertapenem concentrations and hence a risk of treatment failure - exercise caution. Experience in the treatment of severe infections is limited. US LABELLING DIVERGES on two points and should be reconciled by the clinician: it permits intramuscular injection as an alternative for up to 7 days (intravenous infusion up to 14 days), using lidocaine HCl as the diluent, and it gives 500 mg daily for adults with creatinine clearance 30 mL/min/1.73 m2 or less and for end-stage renal disease, plus a 150 mg supplementary dose if ertapenem is given within 6 hours before haemodialysis - whereas the UK SPC says ertapenem should not be used in severe renal impairment or on haemodialysis. Do not mix or co-infuse ertapenem with other medications and do not use diluents containing dextrose (US §2.1).

Paediatric dose

Dose: 15 mg/kg

Route: Intravenous infusion over 30 minutes

Frequency: Twice daily

Max: Not to exceed 1 g/day

eMC §4.2: infants and children 3 months to 12 years of age receive 15 mg/kg twice daily (not to exceed 1 g/day) by the intravenous route. Adolescents 13 to 17 years of age receive the adult dose of 1 g once daily. Safety and efficacy in children below 3 months of age have not been established and no data are available. There are no data in children and adolescents with renal impairment. US labelling adds that ertapenem is not recommended for the treatment of meningitis in the paediatric population because of insufficient CSF penetration. Verify all paediatric dosing against a children's formulary before administration.

Dose adjustments

Renal

eMC §4.2: ertapenem may be used to treat infections in adults with mild to moderate renal impairment; in patients whose creatinine clearance is greater than 30 mL/min/1.73 m2 no dosage adjustment is necessary. There are inadequate data on the safety and efficacy of ertapenem in patients with severe renal impairment to support a dose recommendation, therefore ertapenem should not be used in these patients; the same applies to patients on haemodialysis. There are no data in children and adolescents with renal impairment. NOTE the US labelling differs: it recommends 500 mg daily for adults with creatinine clearance 30 mL/min/1.73 m2 or less and for end-stage renal disease (10 mL/min/1.73 m2 or less), with a 150 mg supplementary dose following dialysis if ertapenem was given within the 6 hours before haemodialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Hypersensitivity to the active substance or to any of the excipients (eMC §4.3)
Hypersensitivity to any other carbapenem antibacterial agent (eMC §4.3)
Severe hypersensitivity (e.g. anaphylactic reaction, severe skin reaction) to any other type of beta-lactam antibacterial agent, e.g. penicillins or cephalosporins (eMC §4.3)
US labelling §4 adds that, because lidocaine HCl is used as the diluent, intramuscular ertapenem is contraindicated in patients with known hypersensitivity to amide-type local anaesthetics

Side effects

Diarrhoea (4.8%), infused vein complication (4.5%) and nausea (2.8%) - the most common reactions in adults; in children and adolescents, infusion site pain (6.1%) and diarrhoea (5.2%)
Laboratory abnormalities: elevated ALT (4.6%), AST (4.6%) and alkaline phosphatase (3.8%), and raised platelet count (3.0%) in adults; decreased neutrophil count (3.0%) and raised ALT (2.9%) and AST (2.8%) in children
Seizures - reported in adults during therapy or in the 14-day follow-up, most commonly in elderly patients, those with pre-existing CNS disorders (e.g. brain lesions or a history of seizures) and/or compromised renal function; encephalopathy has also been reported (myoclonus, seizures, altered mental status, depressed consciousness), with higher risk and possibly prolonged resolution in renal impairment
Antibiotic-associated colitis and pseudomembranous colitis, ranging from mild to life-threatening - consider this diagnosis in patients presenting with diarrhoea; do not give antiperistaltic medicinal products
Uncommon: oral candidiasis, candidiasis, fungal infection, vaginitis. Rare: neutropenia, thrombocytopenia, allergy, pneumonia, urinary tract infection, postoperative wound infection. Not known: anaphylaxis. Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported with beta-lactams - discontinue immediately if an allergic reaction occurs

Interactions

Valproic acid / sodium valproate (divalproex sodium) - concomitant use is not recommended (eMC §4.4). Carbapenems reduce valproic acid concentrations, which may drop below the therapeutic range and increase the risk of breakthrough seizures; antibacterials other than carbapenems should be considered in patients whose seizures are well controlled on valproate (US §7.2)
Probenecid - interferes with the active tubular secretion of ertapenem, increasing ertapenem plasma concentrations; co-administration is not recommended (US §7.1)
The eMC §4.5 interaction section was not captured in this bundle - clinician to review it in the SPC

Clinical monograph

How it works

It inhibits bacterial cell wall synthesis by binding penicillin-binding proteins, and is stable to many beta-lactamases, giving a broad spectrum against Gram-positive and Gram-negative organisms.

Prescribing in practice

There is a risk of cross-hypersensitivity with penicillins and other beta-lactams, so a careful allergy history is essential before use.
Unlike some carbapenems it lacks reliable activity against Pseudomonas aeruginosa and Acinetobacter and enterococci, which limits its empirical use.
Dose adjustment is required in significant renal impairment, and seizures have rarely been reported with carbapenems.

Monitoring

Monitor clinical response, renal function, and for hypersensitivity reactions, CNS effects such as seizures, and signs of antibiotic-associated colitis.

Counselling the patient

Tell the team about any previous reaction to penicillins or other antibiotics.
Report any severe or persistent diarrhoea.
Report any new confusion, twitching or seizures.

Evidence & guidelines

Ertapenem is an established carbapenem option in UK antimicrobial guidance, with once-daily dosing supported by its pharmacokinetic profile.

Reference: BSAC; UKHSA AMR / OPAT; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

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