Meropenem

Meropenem is an ultra-broad spectrum injectable antibiotic used to treat a wide variety of infections, including meningitis and pneumonia. It is a beta-lactam and belongs to the subgroup of carbapenem, similar to imipenem and ertapenem. Meropenem was originally developed by Sumitomo Pharmaceuticals. It is marketed outside Japan by AstraZeneca with the brand names Merrem&reg; and Meronem&reg;. Other brand names include Mepem&reg; (Taiwan) and Meropen&reg; (Japan, Korea). It gained FDA approval in July 1996. It penetrates well into many tissues and body fluids including the cerebrospinal fluid, bile, heart valves, lung, and peritoneal fluid.

Mechanism of action
Meropenem is bactericidal except against Listeria monocytogenes where it is bacteriostatic. It inhibits bacterial wall synthesis like other beta-lactam antibiotics. In contrast to other beta-lactams, it is highly resistant to degradation by beta-lactamases or cephalosporinases. Resistance generally arises due to mutations in penicillin binding proteins, production of metallo-beta-lactamases, or resistance to diffusion across the bacterial outer membrane. Unlike imipenem, it is stable to dehydropeptidase-1 and can therefore be given without cilastatin.

Indications
The spectrum of action includes many gram-positive and gram-negative bacteria and even some anaerobic bacteria. The overall spectrum is similar to imipenem although meropenem is more active against Enterobacteriaceae and less active against gram-positive bacteria. It is also very resistant to extended-spectrum beta lactamases but may be more susceptible to metallo-beta-lactamases. However, meropenem should not be used to treat MRSA infections.

Administration
Meropenem must be administered intravenously. It is supplied as a white crystalline powder to be dissolved in 5% monobasic potassium phosphate solution.

Common adverse effects
The most common adverse effects are diarrhea (4.8%), nausea and vomiting (3.6%), injection-site inflammation (2.4%), headache (2.3%), rash (1.9%), and thrombophlebitis (0.9%). Many of these adverse effects were observed in the setting of severely ill individuals who were already taking many medications. Meropenem also has a reduced potential for causing seizures in comparison with imipenem.