Lefloxin Mechanism of Action

Pharmacology: Pharmacodynamics: Levofloxacin is an active (-)-S form of ofloxacin belonging to fluoroquinolones group. Levofloxacin has a broad spectrum activity by inhibiting DNA gyrase (type II DNA topoisomerases) and topoisomerase IV which is an essential enzyme for the bacterial living and DNA replication. Levofloxacin is considered to be about twice as active as ofloxacin, the racemic substance.
In vitro, Levofloxacin is active against both gram-positive and gram-negative bacteria as following: Gram-positive bacteria: Enterococcus faecalis, Staphylococcus aureus, Staphylococcus saprophyticus, Streptococcus pneumoniae including multidrug-resistant strains (MDRSP), Streptococcus pyogenes.
Gram-negative bacteria: Enterobacter cloacae, Escherichia coli, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Proteus mirabilis, Pseudomonas aeruginosa, Legionella pneumophila.
Others: Chlamydophila pneumoniae (Chlamydia pneumoniae), Mycoplasma pneumoniae, Bacillus anthracis, some strains of Mycobacterium tuberculosis, Mycobacterium fortuitum.
Pharmacokinetics: Levofloxacin is rapidly absorbed and peak plasma concentrations occur within 1 to 2 hours after oral administration. Bioavailability is approximately 99%. Levofloxacin is widely distributed into body tissues. The drug is also distributed to bronchial mucosa and lungs, but penetration into CSF is relatively poor. About 30 to 40% of Levofloxacin is bound to plasma proteins. It is excreted largely unchanged, mainly in the urine. Only small amounts are metabolized to inactive metabolites. The elimination half-life is 6 to 8 hours, however this may be prolonged in patients with renal impairment, therefore dosing interval or dosage adjustment may be required. It is not removed by hemodialysis or peritoneal dialysis.