Cefepime Classification
Cefepime is a fourth-generation cephalosporin antibiotic. 1
Structural and Chemical Characteristics
Cefepime is a semi-synthetic, broad-spectrum cephalosporin with the chemical name 1-[[(6R,7R)-7-[2-(2-amino-4-thiazolyl)-glyoxylamido]-2-carboxy-8-oxo-5-thia-1-azabicyclo [4.2.0]oct-2-en-3-yl]methyl]-1-methylpyrrolidinium chloride, 72-(Z)-(O-methyloxime), monohydrochloride, monohydrate 1
The drug possesses a zwitterionic structure that contributes to more rapid penetration of gram-negative bacterial cell membranes 2, 3
Fourth-Generation Designation Rationale
The "fourth-generation" classification reflects cefepime's enhanced spectrum compared to third-generation cephalosporins, combining the gram-positive activity similar to cefotaxime with gram-negative activity comparable to ceftazidime 4, 5, 3
Cefepime demonstrates activity against many organisms that are resistant to third-generation cephalosporins, including derepressed mutants of Enterobacter species 5
The drug exhibits stability against many common plasmid- and chromosomally-mediated beta-lactamases and is a poor inducer of type I (AmpC) beta-lactamases 4, 5
Distinguishing Features from Other Cephalosporin Generations
Fourth-generation cephalosporins like cefepime have activity against AmpC-producing organisms, which distinguishes them from third-generation cephalosporins 6
Cefepime has low affinity for most type I beta-lactamases, leading to significantly reduced enzymatic degradation compared with other cephalosporins 2
The American College of Clinical Pharmacy notes that cefepime has broader spectrum activity than third-generation cephalosporins, particularly against gram-positive bacteria 7