GENERIC NAME: metronidazole gel

BRAND NAME: Metrogel, Metrogel Vaginal

DRUG CLASS AND MECHANISM: Metronidazole is a man-made drug that is effective against certain bacteria and parasites (protozoa). It is used for treating vaginal infections with protozoa such as Trichomonas vaginalis, ameba, and giardia and also is effective against anaerobic bacterial infections. (Anaerobic bacteria are a type of bacteria that grow without oxygen.) Metronidazole gel also is used for treating rosacea.  Metronidazole was approved by the FDA in 1963.

GENERIC AVAILABLE: No

PRESCRIPTION: Yes

PREPARATIONS: Metrogel (0.75%): 40 gm tube. Metrogel Vaginal (0.75%): 70 gm tube.

STORAGE: The gel should be stored at room temperature, 15-30°C (59-86°F).

PRESCRIBED FOR: Metronidazole gel is used for treating rosacea.  Metronidazole vaginal gel is used for the treatment of bacterial vaginosis (also referred to as Hemophilus vaginitis, Gardnerella vaginitis, or nonspecific vaginitis), a bacterial infection of the vagina. It is not effective in treating another common vaginal infection, Candidal vaginosis ("yeast infection").

DOSING: The usual treatment of rosacea is by application of metronidazole gel twice daily.  The usual dose of the vaginal form of metronidazole gel is one applicatorful (containing 37.5mg of metronidazole) intravaginally twice daily for 5 days. It should be applied once in the morning and once in the evening.

DRUG INTERACTIONS: Alcoholic beverages should not be drunk while being treated with metronidazole vaginal gel since this may result in a reaction with such symptoms as headache, nausea, weakness, confusion and even psychosis. This is the same reaction (disulfiram reaction) that occurs in alcoholics who drink alcohol while taking Antabuse, a drug used to discourage them from drinking alcohol.

Oral metronidazole interacts with warfarin (Coumadin), increasing the latter's blood-thinning properties. Little metronidazole is absorbed from the vagina, and it is not known if the low blood levels achieved with vaginal metronidazole can result in this interaction.

PREGNANCY: Animal studies have not demonstrated a risk to the fetus, but there are no adequate studies in pregnant women.

NURSING MOTHERS: Studies of metronidazole levels in breast milk following intravaginal application have not been done. However, metronidazole is secreted in breast milk in concentrations that are similar to concentrations in the blood. Physicians must weigh the benefit against the potential risk to the infant when considering the use of metronidazole gel in nursing mothers.

SIDE EFFECTS: Approximately 6% of patients (1 in 16) develop symptoms of Candida vaginitis during or shortly after therapy. About 1 in 70 develop vaginal or vulvar itching, 1 in 30 develop gastrointestinal cramps or pain, 1 in 50 develop nausea, and 1 in 60 develop a metallic taste.

Reference: FDA Prescribing Information