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Imipenem hydrate ball-and-stick.png
Systematic (IUPAC) name
(5R,6S)-6-[(1R)-1-hydroxyethyl]-3-({2-[(iminomethyl)amino]ethyl}thio)-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid
Clinical data
Trade names Primaxin
AHFS/ International Drug Names
MedlinePlus a686013
  • AU: B3
  • US: C (Risk not ruled out)
Routes of
Legal status
Legal status
Pharmacokinetic data
Protein binding 20%
Metabolism Renal
Biological half-life 38 minutes (children), 60 minutes (adults)
Excretion Urine (70%)
CAS Number 64221-86-9 YesY
ATC code J01DH51 (WHO)
PubChem CID 5282372
DrugBank DB01598 YesY
ChemSpider 4445535 YesY
KEGG D00206 YesY
ChEBI CHEBI:51799 YesY
Chemical data
Formula C12H17N3O4S
Molar mass 299.347 g/mol

Imipenem (Primaxin) is an intravenous β-lactam antibiotic discovered by Merck scientists Burton Christensen, William Leanza, and Kenneth Wildonger in 1980.[1] It was the first member of the carbapenem class of antibiotics. Carbapenems are highly resistant to the β-lactamase enzymes produced by many multiple drug-resistant Gram-negative bacteria,[2] thus play a key role in the treatment of infections not readily treated with other antibiotics.[3]

It was discovered via a lengthy trial-and-error search for a more stable version of the natural product thienamycin, which is produced by the bacterium Streptomyces cattleya. Thienamycin has antibacterial activity, but is unstable in aqueous solution, so impractical to administer to patients.[4] Imipenem has a broad spectrum of activity against aerobic and anaerobic, Gram-positive and Gram-negative bacteria.[5] It is particularly important for its activity against Pseudomonas aeruginosa and the Enterococcus species. It is not active against MRSA, however.

Mechanism of action[edit]

Imipenem acts as an antimicrobial through inhibiting cell wall synthesis of various Gram-positive and Gram-negative bacteria. It remains very stable in the presence of β-lactamase (both penicillinase and cephalosporinase) produced by some bacteria, and is a strong inhibitor of β-lactamases from some Gram-negative bacteria that are resistant to most β-lactam antibiotics.

Spectrum of bacterial susceptibility and resistance[edit]

Acinetobacter anitratus, Acinetobacter calcoaceticus, Actinomyces odontolyticus, Aeromonas hydrophila, Bacteroides distasonis, Bacteroides uniformis, and Clostridium perfringens are generally susceptible to imipenem, while Acinetobacter baumannii, some Acinetobacter spp., Bacteroides fragilis, and Enterococcus faecalis have developed resistance to imipenem to varying degrees. Not many species are resistant to imipenem except Pseudomonas aeruginosa (Oman) and Stenotrophomonas maltophilia.[6]

Coadministration with cilastatin[edit]

Main article: Imipenem/cilastatin

Imipenem is rapidly degraded by the renal enzyme dehydropeptidase 1 when administered alone, and is always coadministered with cilastatin to prevent this inactivation.[citation needed]

Adverse effects[edit]

Common adverse drug reactions are nausea and vomiting. People who are allergic to penicillin and other β-lactam antibiotics should take caution if taking imipenem, as cross-reactivity rates are low. At high doses, imipenem is seizurogenic.[citation needed]


  1. ^ U.S. Patent 4,194,047
  2. ^ Clissold, SP; Todd, PA; Campoli-Richards, DM (Mar 1987). "Imipenem/cilastatin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic efficacy.". Drugs. 33 (3): 183–241. doi:10.2165/00003495-198733030-00001. PMID 3552595. 
  3. ^ Vardakas, KZ; Tansarli, GS; Rafailidis, PI; Falagas, ME (Dec 2012). "Carbapenems versus alternative antibiotics for the treatment of bacteraemia due to Enterobacteriaceae producing extended-spectrum β-lactamases: a systematic review and meta-analysis.". The Journal of antimicrobial chemotherapy. 67 (12): 2793–803. doi:10.1093/jac/dks301. PMID 22915465. 
  4. ^ Kahan, FM; Kropp, H; Sundelof, JG; Birnbaum, J (Dec 1983). "Thienamycin: development of imipenen-cilastatin.". The Journal of antimicrobial chemotherapy. 12 Suppl D: 1–35. doi:10.1093/jac/12.suppl_d.1. PMID 6365872. 
  5. ^ Kesado, Tadataka; Hashizume, Terutaka; Asahi, Yoshinari (1980). "Antibacterial activities of a new stabilized thienamycin, N-formimidoyl thienamycin, in comparison with other antibiotics". Antimicrobial Agents and Chemotherapy. 17 (6): 912–7. doi:10.1128/aac.17.6.912. PMC 283902free to read. PMID 6931548. 
  6. ^ "Imipenem spectrum of bacterial susceptibility and Resistance" (PDF). Retrieved 4 May 2012. 

Further reading[edit]

External links[edit]