Z-Fix 400 Mechanism of Action

Pharmacology: Pharmacodynamics: Cefixime exerts its bactericidal activity by interfering with the synthesis of the bacterial cell wall. It binds to specific penicillin-binding proteins responsible for the synthesis of peptidoglycan, a heteropolymeric structure that gives the cell wall its mechanical stability. The final stage of peptidoglycan synthesis involves completion of the cross-linking of the terminal glycine residue of the pentaglycine bridge to the fourth residue of the pentapeptide. The transpeptidase that catalyzes this step is inhibited by cephalosporins. Thus, inhibition of the transpeptidase interrupts peptidoglycan synthesis, causing formation of defective cell walls and osmotically unstable spheroplasts and lysis of the bacteria.
Pharmacokinetics: CEFIXIME (Z-FIX 400) dispersible tablets, given orally, are about 40%-50% absorbed from gastrointestinal tract whether administered with or without food; although the rate of absorption may be decreased in the presence of food. Absorption is fairly slow; peak plasma concentrations of 2 to 3 micrograms/ml and 3. 7 to 4.6 micrograms/ml have been reported between 2 and 6 hours after single doses of 200 and 400 mg, respectively. About 65% of cefixime is bound to plasma proteins. The plasma half-life is usually about 3 to 4 hours and may be prolonged when there is renal impairment. Information on the distribution of cefixime in body tissues and fluids is limited. It crosses the placenta. Relatively high concentrations may be achieved in bile and urine. About 20% of an oral dose (or 50% of an absorbed dose) is excreted unchanged in the urine within 24 hours. Up to 60% may be eliminated by non-renal mechanisms; there is no evidence of metabolism but some is probably excreted into the faeces from bile. It is not substantially removed by dialysis.
Microbiology: Antimicrobial Action: As with other cephalosporins, bactericidal action of cefixime results from inhibition of cell-wall synthesis. Cefixime is highly stable in the presence of beta-lactamase enzymes. As a result, many organisms resistant to penicillins and some cephalosporins due to the presence of beta-lactamase may be susceptible to cefixime. Cefixime has been shown to be active against many strains of the gram-positive and gram negative both in vitro and in clinical infections. It has a mode of action and spectrum of activity similar to those of the third-generation cephalosporin cefotaxime, but some Enterobacteriaceae are less susceptible to cefixime. Haemophilus influenzae, Moraxella catarrhalis (Branhamella catarrhalis), and Neisseria gonorrhoeae are sensitive, including penicillinase-producing strains of the Gram positive bacteria, Streptococci are sensitive to cefixime but most strains of staphylococci, enterococci, and Listeria spp. are not Enterobacter spp., Pseudomonas aeruginosa, and Bacteroides spp. are resistant to cefixime.