Ciprofloxacin and norfloxacin, two fluoroquinolone antimicrobials

D. E. Nix, J. M. DeVito

Research output: Contribution to journalReview articlepeer-review

36 Scopus citations


The chemistry, mechanism of action, antimicrobial spectrum, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of ciprofloxacin and norfloxacin are reviewed, and mechanisms of antimicrobial resistance and drug and laboratory interactions are described. Norfloxacin is the first antimicrobial in the fluoroquinolone class to be marketed in the United States; ciprofloxacin is under investigation in clinical trials. The fluoroquinolones are structurally related to nalidixic acid. The activity and spectrum are enhanced by the addition of 6-fluoro and 7-piperazino substituents. Quinolone antimicrobials appear to inhibit DNA gyrase, an enzyme specific and essential for all bacteria, as their primary mechanism of action. As a result, DNA synthesis is inhibited. Ciprofloxacin and norfloxacin are active against gram-negative enteric bacteria, Pseudomonas aeruginosa, Haemophilus influenzae, and Neisseria gonorrhoeae. Ciprofloxacin has good activity against Staphylococcus spp., including methicillin-resistant Staph. aureus. Norfloxacin generally is less potent than ciprofloxacin, particularly against Ps. aeruginosa and Staph. aureus. Peak concentrations occur about one to two hours after an oral administration of either drug. Both drugs are widely distributed in body fluids and tissues and are eliminated by renal excretion, metabolism, and biliary excretion. Dosage reductions are required in several renal dysfunction. Ciprofloxacin and norfloxacin are effective agents for treating urinary-tract infections, including infections caused by Ps. aeruginosa. The recommended dosage of norfloxacin for urinary-tract infections in adults is 400 mg orally every 12 hours; the drug should be given for 7 to 10 days in uncomplicated infections and for 10 to 21 days in complicated ones. The fluoroquinolones may be useful for treating chronic bacterial prostatitis. Ciprofloxacin is potentially useful for treating sexually transmitted diseases. Ciprofloxacin is active against N. gonorrhoeae, including β-lactamase-producing strains and strains that are resistant to tetracycline, and Chlamydia spp. Use of ciprofloxacin for treating gastrointestinal infections and for selective decontamination of the gastrointestinal tract is promising. In open studies, ciprofloxacin has been effective against a variety of infections caused by susceptible organisms. Resistance to ciprofloxacin has developed during treatment of infections caused by Ps. aeruginosa, Staph. aureus, and Serratia marcescens. The most frequently reported adverse effects of either drug are gastrointestinal complaints, headache, and dizziness. Ciprofloxacin and norfloxacin are promising new antimicrobial agents that have potent activity against a broad spectrum of bacterial pathogens. Norfloxacin is currently marketed for the treatment of urinary-tract infections in adults. The exact role of the fluoroquinolones relative to other antimicrobial agents should become clearer as comparative efficacy studies are performed.

Original languageEnglish (US)
Pages (from-to)105-117
Number of pages13
JournalClinical pharmacy
Issue number2
StatePublished - 1987

ASJC Scopus subject areas

  • Pharmaceutical Science


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