MetroGel

Metronidazole is a prescription medication used to treat infections of the reproductive system, gastrointestinal tract, respiratory system, skin, bones and joints, and other areas of the body. Metronidazole may also be used to prevent postoperative infections.

Metronidazole is also available as an over-the-counter medication. The over-the-counter form is used to treat bacterial infections of the vagina. This medication page refers to the prescription forms of metronidazole.

Metronidazole belongs to a group of drugs called nitroimidazole antibiotics. These work by killing organisms that cause infections.

Metronidazole comes in oral, topical, and injectable forms. The directions and frequency of use will vary with the indication for metronidazole.

Do not chew, divide, or break extended release metronidazole tablets. Swallow these tablets whole.

The injectable form of metronidazole will be given directly into a vein (IV) by a healthcare professional.

Common side effects of metronidazole include vomiting, upset stomach, diarrhea, loss of appetite, dry mouth or mouth irritation, and numbness or tingling of the hands and feet.

Metronidazole can also cause dizziness. Do not drive or operate heavy machinery until you know how metronidazole affects you.

Take or use metronidazole exactly as prescribed. Do not drink alcohol while taking or using any form of metronidazole. Alcohol can cause upset stomach, vomiting, stomach cramps, headaches, sweating, and flushing when used at the same time as metronidazole.

Oral forms:

Metronidazole comes in tablet and capsule forms and is taken two or three times a day. Take metronidazole with food to minimize stomach upset.  Do not chew, divide, or break extended release metronidazole tablets. Swallow metronidazole tablets whole.

Topical forms:

Metronidazole comes in gel, cream, and lotion forms and is applied to the skin one or two times a day. The affected skin should be washed with mild soap 15-20 minutes before applying metronidazole. The gel, cream, or lotion should be applied in a thin layer and gently rubbed into the skin. Moisturizers and cosmetics may be applied once the gel, cream, or lotion has dried.

Topical metronidazole may increase sensitivity to sunlight. Avoid unnecessary or prolonged exposure to sunlight. Wear protective clothing, sunscreen, and sunglasses.

Injectable forms:

Metronidazole is available in an injectable form to be given directly into a vein (IV) by a healthcare professional.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of metronidazole at the same time.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your height
• your age

Oral forms:

The recommended dose of metronidazole for the treatment of trichomoniasis is 375 mg two times a day.

The recommended dose of metronidazole for the treatment of amebiasis in adults is 750 mg three times a day.

Topical forms:

The recommended dose of metronidazole for the treatment of rosacea is two applications daily, usually in the morning and evening.

Injectable forms:

The recommended dose range of metronidazole for the treatment of amebiasis in children is 35 to 50 mg/kg every day, divided into three doses.

The recommended dose of metronidazole for the treatment of anaerobic bacterial infections is 7.5 mg/kg every 6 hours. A maximum of 4 grams should not be exceeded within a 24-hour period.

• Store metronidazole at room temperature, away from excess heat and moisture.
• Keep this and all medicines out of the reach of children.
• Protect topical forms of metronidazole from exposure to light.

Metronidazole is an antibiotic that fights bacteria in the body.

Metronidazole topical (for the skin) is used to treat skin lesions caused by rosacea.

Metronidazole topical may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have severe stinging or burning when you apply metronidazole topical.

Common side effects may include:

• mild burning or stinging;

• numbness or tingly feeling in your hands or feet;

• mild skin redness or irritation;

• dry, scaly, or itchy skin;

• nausea; or

• metallic taste in your mouth.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

MetroGel is contraindicated in patients with a history of hypersensitivity to metronidazole or to any other ingredient in the formulation.

Pregnancy

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.

Nursing Mothers

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.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Geriatric Use

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.

Mechanism of Action

The mechanism of action of metronidazole in the treatment of rosacea is unknown.

Pharmacodynamics

The pharmacodynamics of metronidazole in association with the treatment of rosacea are unknown.

Pharmacokinetics

Topical administration of a one gram dose of MetroGel to the face of 13 patients with moderate to severe rosacea once daily for 7 days resulted in a mean ± SD Cmax of metronidazole of 32 ± 9 ng/mL.  The mean ± SD AUC(0-24) was 595 ± 154 ng*hr/mL. The mean Cmax and AUC(0-24) are less than 1% of the value reported for a single 250 mg oral dose of metronidazole. The time to maximum plasma concentration (Tmax) was 6-10 hours after topical application.