Table of Contents
Commonly used Carbapenems
- Imipenem/Cilastatin (renal dehydropeptidase I inhibitor)
Besides these, there are other drugs like tebipenem (1st oral carbapenem), panipenem, tomopenem (has MRSA activity), etc. which fall under carbapenems.
As the name suggests, they have carbapenems attached to beta-lactam ring which provides protection against most beta-lactamases. They have good gram positive, gram negative and anaerobe coverage.
These are effective against beta-lactamase producing organisms like SPACE-M (cephalosporins are often ineffective in these):
- Pseudomonas aeruginosa; Proteus vulgarus, Providencia
Ertapenem lacks good coverage against: APE organisms (hence, referred as gorilla-cillin as well).
- Pseudomonas aeruginosa
Some organisms are able to SPAM carbapenems and hence, do not work well with:
- Stenotrophomonas maltophilia
- Pseudomonas cepacia
- Atypicals (Legionella, Chlamydica, Mycoplasma)
These also do not effectively work against gram-negative bacteria that sometimes produce carbapenemase like Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii.
Mechanism of Action
These are beta-lactam antibiotics and work by interfering with bacterial cell wall synthesis, the details of which can be read in the post below. These are bactericidal antibiotic.
- Renally excreted and require renal dosing
- Imipenem requires cilastatin to decrease inactivation of drugs in proximal renal tubules
- Half-life is ~1 hour except for Ertapenem which has a longer half-life of ~4 hrs (single dose per day may be sufficient)
Other points to be noted
- All these lower seizure threshold and may cause seizure especially in patients with renal dysfuction.
- Imipenem has the highest incidence of seizure.
- Meropenem has a lower risk of seizures and hence, useful in cases of Meningitis.