Microbiology: As with other cephalosporins, the bactericidal action of cefixime results from inhibition of cell wall synthesis. Cefixime is highly stable in the presence of β-lactamase enzymes. As a result, many organisms resistant to penicillins and some cephalosporins due to the presence of β-lactamases, may be susceptible to cefixime.
Gram-Positive: Streptococcus pneumoniae, Streptococcus pyogenes.
Gram-Negative: Haemophilus influenzae (β-lactamase positive and negative strains), Moraxella (Branhamella) catarrhalis (most of which are β-lactamase positive), Escherichia coli, Proteus mirabilis, Neisseria gonorrhoeae (including penicillinase- and nonpenicillinase-producing strains).
Pharmacokinetics: Cefixime, given orally, is about 40-50% absorbed whether administered with or without food; however, time to maximal absorption is increased approximately 0.8 hrs when administered with food. A single 200-mg tab of cefixime produces an average peak serum concentration of approximately 2 mcg/mL.
Peak serum concentrations occur between 2 and 6 hrs following oral administration of single 200-mg tab, a single 400-mg tab, or 400 mg of suspension of cefixime.
Approximately 50% of the absorbed dose is excreted unchanged in the urine within 24 hrs.