In the early 1980's parenteral
third generation cephalosporins changed the hospital use of
antibiotics. The MICs of these
cephalosporins are several dozen times lower than those of first or
second generation cephalosporins for Enterobacteriaceae and they are much more
beta-lactamase stable than
second generation cephalosporins. After years of research, is has finally been possible to develop orally active compounds possessing the same antibacterial activity as parenteral
third generation cephalosporins, either through the use of
prodrugs, or by modifying the molecular structure of drugs.
Cefixime is an example of the latter. The vinyl group at the 3-position of the cephem nucleus is responsible for the intestinal absorption of the intact molecule, primarily by a carrier-mediated transport mechanism. The
aminothiazole ring and the R-oxyimino group on the side-chain at the 7-position are associated with an antibacterial activity similar to that of
third generation cephalosporins. Thousands of adults have been treated by
cefixime for lower respiratory tract, ear-nose-throat and
urinary tract infections, showing that
cefixime is a safe and effective
antimicrobial agent. The major clinical indications for
cefixime in adults are bronchial and pulmonary
infections, acute
otitis or
sinusitis, acute
pyelonephritis with no underlying uropathy, and complicated or uncomplicated lower
urinary tract infections excluding
prostatitis. In all cases, the dosage is 200 mg b.i.d.