|Systematic (IUPAC) name|
|Pregnancy cat.||B3 (AU) B (US)|
|Legal status||℞ Prescription only|
|Protein binding||Inversely proportional to concentration; 85 to 95%|
|Metabolism||Minor hydrolysis of beta-lactam ring, CYP not involved|
|Excretion||Renal (80%) and fecal (10%)|
|Mol. mass||475.516 g/mol|
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Ertapenem has been designed to be effective against Gram negative and Gram positive bacteria. It is not active against MRSA, ampicillin-resistant enterococci, Pseudomonas aeruginosa or Acinetobacter species. Ertapenem also has clinically useful activity against anaerobic bacteria.
Ertapenem has been shown to be active against most isolates of the following micro-organisms in vitro and in clinical infections.
Aerobic and facultative gram-positive microorganisms: Staphylococcus aureus (methicillin susceptible isolates only), Streptococcus agalactiae, Streptococcus pneumoniae (penicillin susceptible isolates only), Streptococcus pyogenes,
Note: Methicillin-resistant staphylococci and Enterococcus spp. are resistant to ertapenem.
Aerobic and facultative gram-negative microorganisms:
Escherichia coli, Haemophilus influenzae (Beta-lactamase negative isolates only), Klebsiella pneumoniae, Moraxella catarrhalis, Proteus mirabilis,
Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides uniformis, Clostridium clostridioforme, Eubacterium lentum, Peptostreptococcus species, Porphyromonas asaccharolytica, Prevotella bivia,
Ertapenem is marketed by Merck as a first-line treatment for community-acquired infections. It should not be used as empirical treatment for hospital-acquired infections because of its lack of activity against Pseudomonas aeruginosa. In practice, it is reserved primarily for use against Extended spectrum beta-lactamase (ESBL)-producing and high level AmpC-producing Gram-negative bacteria.
Ertapenem is dosed as 1g given by intravenous injection over 30 minutes, or 1g diluted with 3.2ml of 1% lidocaine given intramuscularly. There is no oral preparation of ertapenem available. Ertapenem cannot be mixed with glucose.
Ertapenem is excreted primarily (80%) by the kidneys. Metabolism by the liver is not clinically important and does not affect dosing.
Patients on haemodialysis should be given ertapenem at least 6 hours before dialysis. If it is given less than six hours before dialysis, then the patient should be given an additional dose of 150 mg IV after dialysis. Ideally, patients on haemodialysis should be given ertapenem immediately following dialysis.
Acquired resistance to ertapenem is usually mediated by up-regulation of efflux mechanisms and by the selection of porin-deficient mutants. Organisms that produce a metallo-β-lactamase are innately immune to ertapenem (as well as all carbapenems).
There are few adverse effects of ertapenem like confusion and headache, may worsen to convulsions and seizures. The only absolute contra-indication is a previous anaphylactic reaction to ertapenem or other β-lactam antibiotic. There are no studies done in pregnant women, so the manufacturers cannot comment on its safety in pregnancy. In 2006, Ertapenem is now approved for pediatric use in certain infections. Ertapenem is not recommended for children under 3 months of age and children with meningitis.
Use of all antibiotics is associated with increased rates of resistance (although carbapenem resistance is currently rare). There is particular worry that although ertapenem has no clinically useful activity against Pseudomonas aeruginosa, widespread use of ertapenem could still lead to increased carbapenem resistance in Pseudomonas.