General As with other antibiotic preparations, prolonged use may result in overgrowth of nonsusceptible organisms, including fungi. If superinfection occurs, appropriate measures should be initiated. Whenever clinical judgment dictates, the patient should be examined with the aid of magnification, such as slit lamp biomicroscopy and, where appropriate, fluorescein staining. There have been reports of bacterial keratitis associated with the use of multiple dose containers of topical ophthalmic products. These containers have been inadvertently contaminated by patients who, in most cases, had a concurrent corneal disease or a disruption of the ocular epithelial surface. (See Information for Patients.) Carcinogenesis, Mutagenesis, Impairment of Fertility No increase in neoplastic changes was observed with norfloxacin as compared to controls in a study in rats, lasting up to 96 weeks at doses eight to nine times the usual human oral dose***. Norfloxacin was tested for mutagenic activity in a number of in vivo and in vitro tests. Norfloxacin had no mutagenic effect in the dominant lethal test in mice and did not cause chromosomal aberrations in hamsters or rats at doses 30 to 60 times the usual oral dose***. Norfloxacin had no mutagenic activity in vitro in the Ames microbial mutagen test, Chinese hamster fibroblasts and V-79 mammalian cell assay. Although norfloxacin was weakly positive in the Rec-assay for DNA repair, all other mutagenic assays were negative including a more sensitive test (V-79). Norfloxacin did not adversely affect the fertility of male and female mice at oral doses up to 33 times the usual human oral dose***. Pregnancy Teratogenic Effects Pregnancy Category C. Norfloxacin has been shown to produce embryonic loss in monkeys when given in doses 10 times the maximum human oral dose*** (400 mg b.i.d.), with peak plasma levels that are two to three times those obtained in humans. There has been no evidence of a teratogenic effect in any of the animal species tested (rat, rabbit, mouse, monkey) at 6 to 50 times the human oral dose. There are no adequate and well-controlled studies in pregnant women. CHIBROXIN (norfloxacin) Ophthalmic Solution should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Nursing Mothers It is not known whether norfloxacin is excreted in human milk following ocular administration. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions in nursing infants from norfloxacin, a decision should be made to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother (see ANIMAL PHARMACOLOGY). Pediatric Use Safety and effectiveness in infants below the age of one year have not been established. Although quinolones including norfloxacin have been shown to cause arthropathy in immature animals after oral administration, topical ocular administration of other quinolones to immature animals has not shown any arthropathy and there is no evidence that the ophthalmic dosage form of those quinolones has any effects on the weight-bearing joints. Geriatric Use No overall differences in safety or effectiveness have been observed between elderly and young patients. ***All factors are based on a standard patient weight of 50 kg. The usual oral dose of norfloxacin is 800 mg daily. One drop of CHIBROXIN (norfloxacin) Ophthalmic Solution 0.3% contains about 1/6,666 of this dose (0.12 mg). Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.