Ertapenem

drugbox
IUPAC_name = (4"R",5"S",6"S")-3- [(3"S",5"S")-5- [(3-carboxyphenyl)carbamoyl]
pyrrolidin-3-yl] sulfanyl-6-(1-hydroxyethyl)-4-methyl-7-
oxo-1-azabicyclo [3.2.0] hept-2-ene-2-carboxylic acid

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CAS_number = 153832-46-3
ATC_prefix = J01
ATC_suffix = DH03
ATC_supplemental =
PubChem = 150610
DrugBank = APRD00952
C = 22 | H = 25 | N = 3 | O = 7 | S = 1
molecular_weight = 475.516 g/mol
bioavailability = 90% (intramuscular)
protein_bound = Inversely proportional to concentration; 85 to 95%
metabolism = Minor hydrolysis of beta-lactam ring, CYP not involved
elimination_half-life = 4 hours
excretion = Renal (80%) and fecal (10%)
pregnancy_AU = B3
pregnancy_US = B
legal_status = Rx-only
routes_of_administration = Intramuscular, intravenous

Ertapenem is a carbapenem antibiotic marketed by Merck as Invanz. It is structurally very similar to meropenem in that it possess a 1-β-methyl group.

Indications

Ertapenem has been designed to be effective against Gram negative 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 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.

Dosage

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 preparation of ertapenem available. Ertapenem cannot be mixed with glucose.

The marketing slogan for ertapenem is "The Power of One", because the dose is one gram, once a day.

Pharmacology

Unlike imipenem and meropenem, ertapenem is highly protein bound, which explains its long half life (4 hours).

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.

Resistance

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).Fact|date=October 2007

ide effects

There are few adverse effects of ertapenem. 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". [ cite journal
author=Livermore DM, Mushtaq S, Warner M
title=Selectivity of ertapenem for "Pseudomonas aeruginosa" mutants cross-resistant to other carbapenems
journal=J Antimicrob Chemother
year=2005
volume=55
issue=3
pages=306–311
doi= 10.1093/jac/dki009
pmid=15705643 ]

Like many antibiotics, "Clostridium difficile" colitis has been associated with its use.

References