Cefprozil, sometimes spelled cefproxil and marketed under the trade names Cefzil and Cefproz, is a second-generation cephalosporin antibiotic. In Europe it is marketed using the trade names Procef and Cronocef.[citation needed] It can be used to treat bronchitis, ear infections, skin infections, and other bacterial infections.[citation needed] It comes as a tablet and as a liquid suspension. Although there is a widely quoted cross-allergy risk of 10% between cephalosporins and penicillin, an article in the Journal of Family Practice[1] has shown no increased risk for cross-allergy for cefprozil and several other second-generation or later cephalosporins. Currently bacteria like Enterobacter aerogenes, Morganella morganii and Pseudomonas aeruginosa are resistant to cefprozil, while Salmonella enterica serotype Agona and streptococci are susceptible to cefprozil. Some bacteria like Brucella abortus, Moraxella catarrhalis and Streptococcus pneumoniae have developed resistance towards cefprozil in varying degrees. Detailed minimum inhibition concentration information is given by the Cefprozil Susceptibility and Resistance Data sheet.[2] Displacement of the allylic chloride in intermediate (1) with triphenylphosphine gives the phosphonium salt (2). This functionality is then converted to its ylide; condensation with acetaldehyde then leads to the vinyl derivative (3); deprotection then gives cefprozil. Semisynthetic oral cephalosporin consisting of ~90:10 Z/E isomeric mixture.

Source:Wikipedia.org