indication

For the treatment the following moderate to severe infections caused by susceptible isolates of the designated microorganisms: (1) complicated intra-abdominal infections due to Escherichia coli, Clostridium clostridioforme, Eubacterium lentum, Peptostreptococcus species, Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, or Bacteroides uniformis, (2) complicated skin and skin structure infections, including diabetic foot infections without osteomyelitis due to Staphylococcus aureus (methicillin susceptible isolates only), Streptococcus agalactiae, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Bacteroides fragilis, Peptostreptococcus species, Porphyromonas asaccharolytica, or Prevotella bivia, (3) community acquired pneumonia due to Streptococcus pneumoniae (penicillin susceptible isolates only) including cases with concurrent bacteremia, Haemophilus influenzae (beta-lactamase negative isolates only), or Moraxella catarrhalis, (4) complicated urinary tract infections including pyelonephritis due to Escherichia coli, including cases with concurrent bacteremia, or Klebsiella pneumoniae, (5) acute pelvic infections including postpartum endomyometritis, septic abortion and post surgical gynecologic infections due to Streptococcus agalactiae, Escherichia coli, Bacteroides fragilis, Porphyromonas asaccharolytica, Peptostreptococcus species, or Prevotella bivia.

pharmacology

Ertapenem has in vitro activity against gram-positive and gram-negative aerobic and anaerobic bacteria.

mechanism of action

The bactericidal activity of ertapenem results from the inhibition of cell wall synthesis and is mediated through ertapenem binding to penicillin binding proteins (PBPs). In Escherichia coli, it has strong affinity toward PBPs 1a, 1b, 2, 3, 4 and 5 with preference for PBPs 2 and 3. Ertapenem is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases. Ertapenem is hydrolyzed by metallo-beta-lactamases.

biotransformation

The major metabolite is the inactive ring-opened derivative formed by hydrolysis of the β-lactam ring. Ertapenem did not inhibit metabolism mediated by cytochrome P450 (CYP) isoforms 1A2, 2C9, 2C19, 2D6, 2E1, or 3A4 when evaluated by in vitro studies in human liver microsomes. Ertapenem is neither a substrate nor an inhibitor of P-glycoprotein or cytochrome P450 enzymes; significant drug interactions between ertapenem and drugs handled by these systems are not expected [PMID: 15150180]

absorption

Ertapenem is almost completely absorbed following intramuscular administration. The bioavailability of a 1 g intramuscular dose approximated 92% in 26 healthy subjects [77% male; median (range) age, 29 (22–41) years]. Plasma concentrations of total ertapenem were similar whether given intramuscularly or intravenously.

half life

The mean plasma half-life is approximately 4 hours.

route of elimination

Of the 80% recovered in urine, approximately 38% is excreted as unchanged drug and approximately 37% as the ring-opened metabolite.