Warnings for Metrogel
Included as part of the PRECAUTIONS section.
Precautions for Metrogel
Neurologic Disease
Peripheral neuropathy, characterized by numbness or paresthesia of an extremity, has been reported in patients treated with systemic metronidazole. Peripheral neuropathy has been reported with the post approval use of topical metronidazole. Immediately reevaluate METROGEL therapy if abnormal neurologic signs appear. Administer metronidazole with caution to patients with central nervous system diseases.
Blood Dyscrasias
METROGEL is a nitroimidazole; use with care in patients with evidence of, or history of, blood dyscrasia.
Contact Dermatitis
Irritant and allergic contact dermatitis have been reported with METROGEL. If dermatitis occurs, patients may need to discontinue use.
Eye Irritation
Topical metronidazole has been reported to cause tearing of the eyes. Avoid contact with the eyes.
Patient Counseling Information
Advise the patient to read the FDA-approved patient labeling (PATIENT INFORMATION).
Administration Instructions
Use as directed. Avoid contact with the eyes [see WARNINGS AND PRECAUTIONS].
Cleanse treated areas before the application of METROGEL [see DOSAGE AND ADMINISTRATION]
Advise patients to report any adverse reaction to their healthcare providers.
Neurologic Disease
Advise patients to immediately report any abnormal neurologic signs to their healthcare provider [see WARNINGS AND PRECAUTIONS].
Lactation
Advise women not to breastfeed during treatment with METROGEL [see Use In Specific Populations].
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Metronidazole has shown evidence of carcinogenic activity in 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 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.
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.
Use In Specific Populations
Pregnancy
Risk Summary
Available data have not established an association between metronidazole use during pregnancy and major birth defects, miscarriage or other adverse maternal or fetal outcomes. No fetotoxicity was observed after oral administration of metronidazole in pregnant rats or mice. The available data do not allow the calculation of relevant comparisons between the systemic exposures of metronidazole observed in animal studies to the systemic exposures that would be expected in humans after topical use of METROGEL.
The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Lactation
Risk Summary
It is not known whether metronidazole is present in human milk after topical administration. Published literature reports the presence of metronidazole in human milk after oral administration. There are no data on the effects of metronidazole on milk production. Because of the potential for serious adverse reactions, advise patients that breastfeeding is not recommended during treatment with METROGEL.
Pediatric Use
Safety and effectiveness of METROGEL have not been established in pediatric patients.
Geriatric Use
Sixty-six subjects aged 65 years and older were treated with METROGEL in the clinical study. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.