Pharmacology: Pharmacodynamics: Ciprofloxacin has in vitro activity against a wide range of gram-negative and gram-positive organism. The bactericidal action of ciprofloxacin results from interference with the enzyme DNA which is needed for the synthesis of bacterial DNA ciprofloxacin has been shown to be active against most strains of the following organisms both in vitro and in clinical infections: Gram Positive: Staphylococcus aureus (including methicillin-susceptible and methicillin-resistant strains), Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus (Viridans Group).
Gram-negative: Haemophilus influenzae, Pseudomonoas aeruginosa, Serratia marcescencs.
Ciprofloxacin has been shown to be active in vitro against most strains of the following organisms; however, the clinical significance of these data is unknown: Gram-Positive: Enterococcus faecalis (many strains are only moderately susceptible), Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus saprophyticus, Streptococcus pyogenes.
Gram-negative: Acinetobacter calcoaceticus, Escherichia coli, Proteus vulgaris, Susbsp. anitratus, Haemophilus ducreyi, Providencia rettgeri, Aeromonas hydrophila, Haemophilus parainfluenzae, Providencia stuartii, Brucella melitensis, Klebsiella oxytoca, Salmonella enteritidis, Campylobacter coli, Legionella pneumophila, Salmonella typhi, Campylobacter jejuni, Moraxella (Branhamelia) catarrhalis, Shigella sonneii, Citrobacter diversus, Morganella morganii, Shigella flexneri, Citrobacter freundii, Neisseria gonorrhoeae, Vibrio cholerae, Edwardsiella tarda, Neisseria meningitidis, Vibrio parahaemolyticus, Enterobacter aerogenes, Pasteurellia multocida, Vibrio vulnificus, Enterobacter cloacae, Proteus mirabilis, Yersinia enterocolitica.
Other organisms: Chlamydia trachomatis (only moderately susceptible) and Mycobacterium tuberculosis (only moderately susceptible).
Most strains of Pseudomonas cepacia and some strains of Pseudomonas maltophilia are resistant to ciprofloxacin as are most anaerobic bacteria, including Bacteroides fragilis and Clostridium difficile. The minimal bactericidal concentration (MBC) generally does not exceed the minimal inhibitory concentration (MIC) by more than a factor of 2. Resistance to ciprofloxacin in vitro usually develops slowly (multiple-step mutation). Ciprofloxacin does not cross-react with other antimicrobial agents such as beta-lactams or aminoglycosides; therefore, organisms resistant of these drugs may be susceptible to ciprofloxacin.
Pharmacokinetics: Systemic absorption: After topical ocular administration, ciprofloxacin is also absorbed systemically.