Mosi Mechanism of Action

Pharmacology: Pharmacodynamics: Moxifloxacin has in vitro activity against a wide range of Gram-positive and Gram-negative microorganisms. Moxifloxacin inhibits the topoisomerase II (DNA gyrase) and topoisomerase IV required for bacterial DNA replication, transcription, repair and recombination. The C8-methoxy moiety of moxifloxacin also lessens the selection of resistant mutants of Gram-positive bacteria compared to the C8-methoxy moiety found in the older fluoroquinolones. Moxifloxacin's bulky C7 substituent group interferes with the quinolone efflux pump mechanism of bacteria. Moxifloxacin is often bacteriacidal at concentrations equal to or slightly greater than the inhibitory concentrations. Fluoroquinolones, including moxifloxacin is differ in chemical structure and mode of action from β-lactam antibiotics, macrolides and aminoglycosides, and therefore may be active against bacteria resistant to β-lactam antibiotics, macrolides and aminoglycosides. Therefore, organism resistant to these drugs may be susceptible to moxifloxacin. In-vitro resistance to moxifloxacin develops slowly via multiple-step mutations and occurs at a general frequency between 10^-9 to 10^-11 for Gram-positive bacteria.
Moxifloxacin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections: Gram-positive bacteria: Corynebacterium sp., Microbacterium sp., Micrococcus luteus [including erythromycin, gentamicin, tetracycline, and/or trimethoprim resistant strains], Staphylococcus aureus [including methicillin, erythromycin, gentamicin, ofloxacin, tetracycline and/or trimethoprim resistant strains], Staphylococcus epidermidis [including methicillin, erythromycin, gentamicin, ofloxacin, tetracycline and/or trimethoprim resistant strains]. Staphylococcus haemolyticus [including methicillin, erythromycin, gentamicin, ofloxacin, tetracycline and/or trimethoprim resistant strains], Staphylococcus hominis [including methicillin, erythromycin, gentamicin, ofloxacin, tetracycline and/or trimethoprim resistant strains], Staphylococcus warneri [including erythromycin resistant strains], Streptococcus mitis [including penicillin, erythromycin, tetracycline and/or trimethoprim resistant strains], Streptococcus pneumoniae [including penicillin, erythromycin, gentamicin, tetracycline and/or trimethoprim resistant strains], Streptococcus viridans [including penicillin, erythromycin, tetracycline and/or trimethoprim resistant].
Gram-negative bacteria: Actinetobacter sp., Haemophilus "alconae" [including ampicillin resistant strains], Haemophilus influenzae [including ampicillin resistant strains], Klebsiella pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa.
Other microorganisms: Chlamydia trachomatis.
Moxifloxacin has been shown to be active in vitro against most strains of the following organisms; however, the significance of these data is unknown. (See table.)

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Pharmacokinetics: Following topical ocular administration of MOSI, moxifloxacin was absorbed into the systemic circulation. Study on the plasma concentration of moxifloxacin had taken placed and the mean steady state Cmax and AUC were 2.7 ng/ml and 41.9 ng.hr/ml. The plasma half-life of moxifloxacin was estimated to be 13 hours.