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Noritate (Metronidazole Topical) - Drug Interactions, Contraindications, Overdosage, etc

 
 



DRUG INTERACTIONS

Carcinogenesis, Mutagenesis and Impairment of Fertility

Metronidazole has shown evidence of carcinogenic activity in a number of studies involving chronic, oral administration in mice and rats but not in studies involving hamsters.

In several long term studies in mice, oral doses of approximately 225 mg/m2/day or greater (approximately 37 times the human topical dose on a mg/m2 basis) were associated with an increase in pulmonary tumors and lymphomas. Several long term oral studies in the rat have shown statistically significant increases in mammary and hepatic tumors at doses >885 mg/m2/day (144 times the topical human dose).

Metronidazole has shown evidence of mutagenic activity in several in vitro bacterial assay systems. In addition, a dose-related increase in the frequency of micronuclei was observed in mice after intraperitoneal injections. An increase in chromosomal aberrations in peripheral blood lymphocytes was reported in patients with Crohn's disease who were treated with 200 to 1200 mg/day of metronidazole for 1 to 24 months. However, in another study, no increase in chromosomal aberrations in circulating lymphocytes was observed in patients with Crohn's disease treated with the drug for 8 months.

In one published study, using albino hairless mice, intraperitoneal administration of metronidazole at a dose of 45 mg/m2/day (approximately 7 times the human topical dose on a mg/m2 basis) was associated with an increase in ultraviolet radiation-induced skin carcinogenesis. Neither dermal carcinogenicity nor photocarcinogenicity studies have been performed with NORITATE or any marketed metronidazole formulations.

Pregnancy

Teratogenic Effects

Pregnancy Category B

There are no adequate and well controlled studies with the use of NORITATE in pregnant women. Metronidazole crosses the placental barrier and enters the fetal circulation rapidly. No fetotoxicity was observed after oral administration of metronidazole to rats or mice at 200 and 20 times, respectively, the expected clinical dose. However, oral metronidazole has shown carcinogenic activity in rodents. Because animal reproduction studies are not always predictive of human response, NORITATE should be used during pregnancy only if clearly needed.

CONTRAINDICATIONS

NORITATE is contraindicated in those patients with a history of hypersensitivity to metronidazole or to any other ingredient in this formulation.

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