Sign Out
Antibacterial agent.
Pharmacology: Norfloxacin is a fluoroquinolone having a fluorine atom at position 6 which provides increased potency against gram-negative organisms. Position 7 carries a piperazine moiety which gives antipseudomonal activity. The fluorine also contributes to the electron stability of the molecule.
Norfloxacin inhibits the gyrase-mediated DNA supercoiling at concentrations that correlate well with those required to inhibit bacterial growth (0.1-10 mcg/mL). Eukaryotic cells contain type-II DNA topoisomerase in place of DNA gyrase. Norfloxacin inhibits this at very high concentrations (100-1000 mcg/mL).
Tinidazole is bactericidal against anaerobic organisms at a minimum concentration, which is generally the same as or twice, the respective inhibitory concentration. The specific mode of action of tinidazole against anaerobic bacteria is not clear, but it is probably the same as that of metronidazole. After entering the microorganism by diffusion, it is reduced to intermediate compounds, which cause cytotoxicity, probably by damaging DNA. Its selectively high activity against anaerobic organisms has suggested interference with electron transport form NADPH or other reduced substrates.
Microbiology: Norfloxacin is effective against a wide range of gram-positive and gram-negative organisms by inhibiting the synthesis of bacterial DNA gyrase with consequent loss of DNA supercoiling. The following bacteria have been found to be susceptible to norfloxacin in vitro, in urinary tract infections: Pseudomonas aeruginosa, Staphylococcus and Hafnia spp, E. coli, Morganella morganii, Proteus mirabilis, Citrobacter sp.
Norfloxacin has also been found to be effective against the Alcaligenes and Flavobacterium sp. Other species eg, Neisseria gonorrhoeae, Bacillus cereus, Shigella, Salmonella, Campylobacter, Vibrio parahaemolyticus have also been found to be susceptible.
Tinidazole is active in vitro against most obligate anaerobic bacteria.
Loxone T: Gram-Positive Aerobes: Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus agalactiae.
Gram-Negative Aerobes: Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Klebsiella coli, Neisseria gonorrhoeae, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens.
Pharmacokinetics: Norfloxacin is absorbed rapidly from the gut with peak levels reached in 1 hr. Food delays absorption of norfloxacin. It is widely distributed and high levels are found in urine. It crosses the placenta but is not detectable in breast milk. It is partly metabolised and excreted in urine and bile. It has a half-life of 3 hrs, which increases with renal damage.
