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 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 microorganisms 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,
Anaerobic microorganisms:
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.
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).
Side 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.
Like many antibiotics, Clostridium difficile colitis has been associated with its use.
References
Category:Carbapenem antibiotics
Category:Benzoic acids
Category:Anilides
Category:Pyrrolidines
