Meropenem is an ultra-broad-spectrum injectable β-lactam antibiotic used to treat a wide variety of infections. Meropenem has been shown to inhibit penicillinase-negative, -positive and methicillin-susceptible staphylococci [1].
In vitro: The meropenem MICs for penicillin-resistant Streptococcus pneumoniae were higher than for the penicillin-susceptible strains but the organisms remained susceptible. Clinical susceptibility in vitro to meropenem was defined by MICs of ≤4 mg/L, intermediate susceptibility by MICs of 8 mg/L and MICs of ≥16 mg/L define resistance; equivalent figures for zones of growth inhibition were ≥14 (susceptible), 12-13 (intermediate) and ≤11 (resistant) mm [1].Meropenem was 2- to 4-fold more active than imipenem against Gram-negative organisms and its spectrum of antimicrobial activity was wider than those of all other drugs tested.Meropenem inhibited all anaerobic bacteria at less than or equal to 8 mg/L and 0.25 mg/L inhibited 50% of strains. Meropenem MICs were not significantly influenced by high inocula and the drug was generally bactericidal [2]. Meropenem bound most strongly to penicillin-binding protein 2 of Escherichia coli and Pseudomonas aeruginosa, and to penicillin-binding proteins 1 of Staphylococcus aureus [3].Meropenem had one identified metabolite, a β-lactam ring-opened form which is devoid of microbiological activity [4].
In vivo: In rabbits, meropenem significantly increased the plamsa total clearance of valproate to about 1.5 times compared to the control (6.09 mL/min/kg vs. 4.28 mL/min/kg). Meropenem significantly increased the urinary excretion of valproate- glucuronide in rabbits [5].
References:
[1] Edwards J R. Meropenem: a microbiological overview [J]. Journal of Antimicrobial Chemotherapy, 1995, 36 (suppl A): 1-17.
[2] Jones R N, Barry A L, Tbornsberry C. In-vitro studies of meropenem [J]. Journal of Antimicrobial Chemotherapy, 1989, 24 (suppl A): 9-29.
[3] Yang Y, Bhachech N, Bush K. Biochemical comparison of imipenem, meropenem and biapenem: permeability, binding to penicillin-binding proteins, and stability to hydrolysis by β-lactamases [J]. Journal of Antimicrobial Chemotherapy, 1995, 35 (1): 75-84.
[4] Drusano G L, Hutchison M. The pharmacokinetics of meropenem [J]. Scandinavian journal of infectious diseases.Supplementum, 1994, 96: 11-16.
