Penem

A penem is a type of unsaturated β-lactam with a sulfur atom in the five-membered ring. Penems do not occur naturally; all are synthetic.[1] Related to penems are carbapenems. Where penems have a sulfur, carbapenems have another carbon.[2]

An example is faropenem.[3]

Structure

Faropenem, a penem. Note sulfur and double bond in ring.
Imipenem, a carbapenem. Although imipenem has a sulfur, the sulfur is not in the ring.
Benzylpenicillin, a Penicllin. Note the absence of the double bond in the ring.

Penem molecules do not occur naturally, and production of penems is an entirely synthetic process.

Five main penem subgroups thiopenems, oxypenems, aminopenems, alkylpenems, and arylpenems have been produced and are distinguished by the side chain (at position 2) of the unsaturated five-membered ring. One structurally distinct penem is BRL 42715. This molecule has no substitution at the above position, but has a bulky group attached to the β-lactam ring, and it displays effective inhibition of class C β-lactamases, but no antimicrobial activity.

One possible consequence of these structural differences of penems from other β-lactams may be reduced immunogenicity and immunogenic cross-reactivity.

References

  1. Richard Wise (1990). "The carbapenems and Penem Antibiotics—a brief review". Antimicrobic Newsletter. 7 (10): 73–78. doi:10.1016/0738-1751(90)90045-E.
  2. "Medscape.com".
  3. Milazzo I, Blandino G, Caccamo F, Musumeci R, Nicoletti G, Speciale A (March 2003). "Faropenem, a new oral penem: antibacterial activity against selected anaerobic and fastidious periodontal isolates". Journal of Antimicrobial Chemotherapy. 51 (3): 721–5. doi:10.1093/jac/dkg120. PMID 12615878.

Further reading

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