Ertapenem, the first group of carbapenems, is a 1-β-methyl carbapenem with potent in vitro activity against a broad spectrum of bacterial pathogens including Gram-positive and Gram-negative aerobic and anaerobic pathogens [1].

In vitro: In E.coli, ertapenem binds to penicillin binding proteins (PBPs) 1a, 1b, 2, 3, 4 and 5, showing highest affinity for PBPs 2 and 3 [1]. MIC90s for most species of Enterobacteriaceae were < 1 mg/L. MIC90s for most Bacteroides fragilis group isolates ranged from 1 to 4 mg/L, and MIC90s were species specific for Clostridium, ranging from 0.06 mg/L for Clostridium perfringens to 4 mg/L for Clostridiumclostridioforme [2].

In vivo: In healthy young men and women volunteers, the mean concentration of ertapenem in plasma ranged from ~145 to 175 μg/ml at the end of a 30-min infusion, from ~30 to 34 μg/ml at 6 h, and from ~9 to 11 μg/ml at 12 h. The mean plasma t1/2 ranged from 3.8 to 4.4 h. About 45% of the plasma clearance (CLP) was via renal clearance [3].

Clinical trials: Ertapenem was highly effective in patients with a range of disease severity within each indication, including elderly patients and patients with severe infections. Ertapenem is not hepatically metabolized and is primarily eliminated by the renal route; dose reduction to 0.5 g once a day is required in patients with severe renal insufficiency. Ertapenem is rapidly bactericidal. The most common adverse reactions reported with ertapenem were diarrhoea, nausea, infused vein complication, vaginitis, headache in females, phlebitis/thrombophlebitis, vomiting and elevated aminotransferase levels.

References:
[1].? Shah P M, Isaacs R D. Ertapenem, the first of a new group of carbapenems[J]. Journal of antimicrobial Chemotherapy, 2003, 52(4): 538-542.
[2].? Wexler H M. In vitro activity of ertapenem: review of recent studies[J]. Journal of Antimicrobial Chemotherapy, 2004, 53(suppl 2): ii11-ii21.
[3].? Majumdar A K, Musson D G, Birk K L, et al. Pharmacokinetics of ertapenem in healthy young volunteers[J]. Antimicrobial Agents and Chemotherapy, 2002, 46(11): 3506-3511.