Cephalexin molecule in 3-D

The Cephalexin molecule - rotatable in 3 dimensions

Cephalexin (Cefalexin) is an antibiotic of the "first generation" Cephalosporin group (a cephem). Like penicillin, it contains a beta-lactam "ring". Attached to this is a D-phenylglycyl group as substituent at the 7-amino position and an unsubstituted methyl group at the 3-position. Incidentally the phenylglycyl group is the same side-chain as ampicillin, which probably explains similarities in adverse reactions in some patients.

It is used to treat infections by organisms such as Proteus mirabilis, Esherichia coli, Klebsiella pneumoniae, but not MRSA.


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