Pharmacology: Antibacterial Activity: Cefixime has a bactericidal and broad-spectrum activity against gram-positive and gram-negative microorganisms. As with other oral cephalosporins, cefixime has potent activity against gram-positive microorganisms eg, Streptococcus sp, Streptococcus pneumoniae and gram-negative microorganisms eg, Branhamella catarrhalis, Escherichia coli, Proteus sp and Haemophilus influenzae. Its mechanism of action is by inhibition of cell wall synthesis. Cefixime has high affinity for penicillin-binding proteins (PBP) 1 (1a, 1b and 1c) and 3, with the site of activity varying according to the strains of organisms. Cefixime is stable to β-lactamase produced by many organisms and has a good activity against β-lactamase-producing organisms.
Pharmacokinetics: Serum Concentration: Following oral administration of a single dose of 50, 100 and 200 mg (potency) of cefixime in healthy, fasted adults, peak serum concentration within 4 hrs after administration were 0.69, 1.13 and 1.95 mcg/mL, respectively. The serum half-life is 2.3-2.5 hrs. Following oral administration of a single dose of 1.5, 3 or 6 mg (potency)/kg of cefixime in pediatrics with normal renal function, peak serum concentration within 3-4 hrs after administration were 1.14, 2.01 and 3.97 mcg/mL, respectively. The serum half-life is 3.2-3.7 hrs.
Distribution (Tissue Penetration): Penetration into sputum, tonsil, maxillary sinus mucosal tissue, otorrhea, biliary fluid and gallbladder tissue is good.
Metabolism: No antibacterially active metabolites are found in the serum and urine.
Elimination: Cefixime is primarily excreted via urine. The extent of urinary excretion (up to 12 hrs) after oral administration of 50, 100 or 200 mg (potency) in healthy, fasted adults was about 20-25% from administered dose. Peak urine concentration of 42.9, 62.2 and 82.7 mcg/mL, respectively, was reached within 4-6 hrs after administration. The extent of urinary excretion (up to 12 hrs) after oral administration of 1.5, 3 or 6 mg (potency)/kg body weight in pediatrics with normal renal function was about 13-20%.