ciprofloxacin brands

Molecular formula: C17H18FN3O3

Ciprofloxacin acts on bacterial topoisomerase II (DNA gyrase) and topoisomerase IV. Ciprofloxacin's targeting of the alpha subunits of DNA gyrase prevents it from supercoiling the bacterial DNA which prevents DNA replication. The mechanism by which ciprofloxacin's inhibition of DNA gyrase or topoisomerase IV results in death in susceptible organisms has not been fully determined. Unlike beta-lactam anti-infectives, which are most active against susceptible bacteria when they are in the logarithmic phase of growth, studies using Escherichia coli and Pseudomonas aeruginosa indicate that ciprofloxacin can be bactericidal during both logarithmic and stationary phases of growth; this effect does not appear to occur with gram-positive bacteria (e.g., Staphylococcus aureus). In vitro studies indicate that ciprofloxacin concentrations that approximate the minimum inhibitory concentration (MIC) of the drug induce filamentation in susceptible organisms; high concentrations of the drug result in enlarged or elongated cells that may not be extensively filamented. Although the bactericidal effect of some fluoroquinolones (e.g., norfloxacin) evidently requires competent RNA and protein synthesis in the bacterial cell, and concurrent use of anti-infectives that affect protein synthesis (e.g., chloramphenicol, tetracyclines) or RNA synthesis (e.g., rifampin) inhibit the in vitro bactericidal activity of these drugs, the bactericidal effect of ciprofloxacin is only partially reduced in the presence of these anti-infectives. This suggests that ciprofloxacin has an additional mechanism of action that is independent of RNA and protein synthesis. Ciprofloxacin usually is bactericidal in action. Like other fluoroquinolone anti-infectives, ciprofloxacin inhibits DNA synthesis in susceptible organisms via inhibition of the enzymatic activities of 2 members of the DNA topoisomerase class of enzymes, DNA gyrase and topoisomerase IV. DNA gyrase and topoisomerase IV have distinct essential roles in bacterial DNA replication. DNA gyrase, a type II DNA topoisomerase, was the first identified quinolone target; DNA gyrase is a tetramer composed of 2 GyrA and 2 GyrB subunits. DNA gyrase introduces negative superhelical twists in DNA, an activity important for initiation of DNA replication. DNA gyrase also facilitates DNA replication by removing positive super helical twists. Topoisomerase IV, another type II DNA topoisomerase, is composed of 2 ParC and 2 ParE subunits. DNA gyrase and topoisomerase IV are structurally related; ParC is homologous to GyrA and ParE is homologous to GyrB. Topoisomerase IV acts at the terminal states of DNA replication by allowing for separation of interlinked daughter chromosomes so that segregation into daughter cells can occur. Fluoroquinolones inhibit these topoisomerase enzymes by stabilizing either the DNA-DNA gyrase complex or the DNA-topoismerase IV complex; these stabilized complexes block movement of the DNA replication fork and thereby inhibit DNA replication resulting in cell death. ... Ciprofloxacin is cytotoxic to a variety of cultured mammalian cell lines at concn that deplete cells of mtDNA. The IC50 values for ciprofloxacin varied from 40-80 ug/ml depending on the cell line tested. Cytotoxicity required continuous exposure of cells to drug for 2-4 days, which corresponded to approx three or four cell doublings. Shorter times of drug exposure did not cause significant cytotoxicity. In addition, cells became drug resistant when they were grown under conditions that bypassed the need for mitochondrial respiration. Resistance was not due to a decr in cellular drug accumulation, ... /indicating/ that ciprofloxacin cytotoxicity is caused by the loss of mtDNA encoded functions. Analysis of mtDNA from ciprofloxacin treated cells revealed the presence of site specific, double stranded DNA breaks. ... Exonuclease protection studies indicated that the 5'-, but not the 3', ends of the drug induced DNA breaks were tightly assoc

Source: PubChem (NCBI) · compound 2764