Pacxime Mechanism of Action

Pharmacotherapeutic Group: Antimicrobial (chemotherapeutic) agents, broad and medium spectrum antibiotics.
Pharmacology: Pharmacodynamics: Cefixime is an orally-active cephalosporin antibiotic which has in vitro bactericidal activity against a wide variety of gram-positive and gram-negative organisms including Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, Proteus mirabilis, Klebsiella sp, Haemophilus influenzae (positive and negative β-lactamases), Moxarella (Branhamella) catarrhalis (positive and negative β-lactamases). Cefixime is stable in the presence of β-lactamase enzymes.
Most strains of enterococci (Streptococcus faecalis, group D streptococci) and staphylococci (including coagulase positive and negative strains and methicillin-resistant strains) are resistant to Cefixime. In addition, most strains of Enterobacter and Pseudomonas, Bacteroides fragilis, Listeria monocytogenes and Clostridia are resistant to Cefixime.
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 Cefixime 200 mg tablet produces an average peak serum concentration (C_max) of approximately 2 mcg/mL (range 1-4 mcg/mL); a single Cefixime 100 mg dispersible tablet produces an average C_max of approximately 1 mcg/mL (range 0.5-2 mcg/mL). Peak serum concentrations occur between 2 and 6 hrs following oral administration of a single 200 mg tablet or a single 100 mg tablet of cefixime.
Approximately 50% of the absorbed dose is excreted unchanged in the urine in 24 hrs. In animal studies, it was noted that cefixime is also excreted in the bile in excess of 10% of the administered dose. Serum protein-binding is concentration-independent with a bound fraction of approximately 65%.
The serum half-life (t_½) of cefixime in healthy subjects is independent of dosage form and averages from 3-4 hrs but may range up to 9 hrs in some normal volunteers. Average area under time curve (AUC) at steady state in elderly patients are approximately 40% higher than average AUC in other healthy adults.
In subjects with moderate renal impairment [creatinine clearance (CrCl) 20-40 mL/min], the average serum t_½ of cefixime is prolonged to 6.4 hrs. In severe renal impairment (CrCl 5-20 mL/min), the t_½ increased to an average of 11.5 hrs. Cefixime is not cleared significantly from the blood by hemodialysis or peritoneal dialysis. However, a study indicated that with doses of 400 mg, patients undergoing hemodialysis have similar profiles as subjects with CrCl 21-60 mL/min. There is no evidence of metabolism of cefixime in vivo.