Cefditoren has MIC50/MIC90 results for Moraxella catarrhalis and Haemophilus influenzae of 0.12/0.5 and < or = 0.008/0.015 mg/mL, respectively. [1] Cefditoren (MIC(90), 0.5 mg/mL) is 4- to 128-fold more active than comparison beta-lactams against the pneumoococci and was the most potent beta-lactam (including penicillin) versus beta-haemolytic streptococci. Cefditoren (MIC(90) in mg/mL/% susceptible) activity against all tested H. influenzae (0.03/100) and M. catarrhalis (0.06-0.5/100) is comparable to Cefixime and significantly greater than cefaclor. Cefditoren pharmacokinetics demonstrate a T(1/2) of 1.5-2 hours and C(max) values of 2.8 and 4.6 mg/mL, respectively with 200 or 400 mg doses of Cefditoren pivoxil. [2] Cefditoren possesses a broad-spectrum of cidal antibacterial activity against both Gram-positive and Gram-negative species with stability to many beta-lactamases of clinical importance. [3] Cefditoren is also effective against methicillin-susceptible strains of Staphylococcus aureus. Cefditoren has compared favorably against other orally administered antibiotics used against the most commonly isolated respiratory tract pathogens. [4] Cefditoren up-regulates the expression levels of Mrp2, Bcrp and Oat2, and down-regulate P-gp and Oct1 mRNA expression. [5]