Imipenem (trade name Primaxin among others) is an intravenous β-lactam

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, ...

discovered by Merck scientists Burton Christensen, William Leanza, and Kenneth Wildonger in the mid-1970s. Carbapenems are highly resistant to the β-lactamase enzymes produced by many multiple drug-resistant Gram-negative bacteria, thus play a key role in the treatment of infections not readily treated with other antibiotics. Imipenem was patented in 1975 and approved for medical use in 1985. 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 ''Streptomyces cattleya'' is a Gram-positive bacterium which makes cephamycin, penicillin and thienamycin. The bacterium expresses a fluorinase enzyme, and the organism has been used to understand the biosynthesis of fluoroacetate and the antibac ...

''. Thienamycin has antibacterial activity, but is unstable in aqueous solution, so impractical to administer to patients. Imipenem has a broad spectrum of activity against aerobic and

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bac ...

and

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

. It is particularly important for its activity against ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic– facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aer ...

'' and the ''

Enterococcus ''Enterococcus'' is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical charac ...

'' species. It is not active against MRSA, however.

Medical uses

Spectrum of bacterial susceptibility and resistance

''Acinetobacter anitratus'', '' Acinetobacter calcoaceticus'', ''Actinomyces odontolyticus'', '' Aeromonas hydrophila'', ''Bacteroides distasonis'', ''Bacteroides uniformis'', and ''

Clostridium perfringens ''Clostridium perfringens'' (formerly known as ''C. welchii'', or ''Bacillus welchii'') is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium of the genus '' Clostridium''. ''C. perfringens'' is ever-present in nature an ...

'' are generally susceptible to imipenem, while ''

Acinetobacter baumannii ''Acinetobacter baumannii'' is a typically short, almost round, rod-shaped ( coccobacillus) Gram-negative bacterium. It is named after the bacteriologist Paul Baumann. It can be an opportunistic pathogen in humans, affecting people with compromi ...

, some

Acinetobacter ''Acinetobacter'' is a genus of gram-negative bacteria belonging to the wider class of Gammaproteobacteria. ''Acinetobacter'' species are oxidase-negative, exhibit twitching motility, and occur in pairs under magnification. They are importan ...

'' spp., '' Bacteroides fragilis'', and '' Enterococcus faecalis'' have developed resistance to imipenem to varying degrees. Not many species are resistant to imipenem except ''

'' (Oman) and '' Stenotrophomonas maltophilia''.

Coadministration with cilastatin

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

Adverse effects

Common

adverse drug reaction An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The meaning of this term ...

s are nausea and vomiting. People who are allergic to

penicillin Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using ...

and other β-lactam antibiotics should take caution if taking imipenem, as cross-reactivity rates are high. At high doses, imipenem is seizurogenic.

Mechanism of action

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.

References

External links

* {{Portal bar , Medicine Carbapenem antibiotics Enantiopure drugs Merck & Co. brands GABAA receptor negative allosteric modulators