METROGEL Gel Ref.[10873] Active ingredients: Methronidazole

5.1 Neurologic Disease

Peripheral neuropathy, characterized by numbness or paresthesia of an extremity has been reported in patients treated with systemic metronidazole. Although not evident in clinical trials for topical metronidazole, peripheral neuropathy has been reported with the post approval use. The appearance of abnormal neurologic signs should prompt immediate reevaluation of METROGEL therapy. Metronidazole should be administered with caution to patients with central nervous system diseases.

5.2 Blood Dyscrasias

Metronidazole is a nitroimidazole; use with care in patients with evidence of, or history of, blood dyscrasia.

5.3 Contact Dermatitis

Irritant and allergic contact dermatitis have been reported. If dermatitis occurs, patients may need to discontinue use.

5.4 Eye Irritation

Topical metronidazole has been reported to cause tearing of the eyes. Avoid contact with the eyes.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
In a controlled clinical trial, 557 patients used metronidazole gel, 1% and 189 patients used the gel vehicle once daily for up to 10 weeks. The following table summarizes selected adverse reactions that occurred at a rate of ≥1%:

Table 1. Adverse Reactions That Occurred at a Rate of ≥1%:

Table 2. Local Cutaneous Signs and Symptoms of Irritation That Were Worse Than Baseline:

The following additional adverse experiences have been reported with the topical use of metronidazole: skin irritation, transient redness, metallic taste, tingling or numbness of extremities, and nausea.

The following adverse reaction has been identified during post approval use of topical metronidazole: peripheral neuropathy. Because this reaction is reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate the frequency or establish a causal relationship to drug exposure.

Oral metronidazole has been reported to potentiate the anticoagulant effect of coumarin and warfarin, resulting in a prolongation of prothrombin time. Drug interactions should be kept in mind when METROGEL is prescribed for patients who are receiving anticoagulant treatment, although they are less likely to occur with topical metronidazole administration because of low absorption.

Teratogenic Effects: Pregnancy Category B.

There are no adequate and well-controlled studies with the use of METROGEL in pregnant women.

Metronidazole crosses the placental barrier and enters the fetal circulation rapidly. No fetotoxicity was observed after oral administration of metronidazole in 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, METROGEL should be used during pregnancy only if clearly needed.

After oral administration, metronidazole is secreted in breast milk in concentrations similar to those found in the plasma. Even though blood levels taken after topical metronidazole application are significantly lower than those achieved after oral metronidazole a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother and the risk to the infant.

Safety and effectiveness in pediatric patients have not been established.

Sixty-six subjects aged 65 years and older were treated with metronidazole gel, 1% 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.