Moxifcin Eye Drops 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-H moiety found in older fluoroquinolones. Moxifloxacin's bulky C-7 substituent group interferes with the quinolone efflux pump mechanism of bacteria.
Moxifloxacin is often bactericidal at concentrations equal to or slightly greater than inhibitory concentrations.
Fluoroquinolones, including moxifloxacin, 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, organisms 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 species; Microbacterium species; 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 strains].
Gram-negative bacteria: Acinetobacter species; 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 clinical significance of these data is unknown. (See Table 1.)

Click on icon to see table/diagram/image

Pharmacokinetics: Following topical ocular administration of this product, moxifloxacin was absorbed into the systemic circulation. The mean steady-state C_max and AUC were 2.7 ng/mL and 41.9 ng·hr/mL, respectively. These exposure values are approximately 1,600 and 1,200 times lower than the mean C_max and AUC reported after well-tolerated therapeutic 400mg oral doses of moxifloxacin. The plasma half-life of moxifloxacin was estimated to be 13 hours.