Metronidazole

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Metronidazole Prescribing Information

Symptomatic Trichomoniasis.

Metronidazole is indicated for the treatment of

T. vaginalis

infection in females and males when the presence of the trichomonad has been confirmed by appropriate laboratory procedures (wet smears and/or cultures).

Asymptomatic Trichomoniasis.

Metronidazole is indicated in the treatment of asymptomatic

T. vaginalis

infection in females when the organism is associated with endocervicitis, cervicitis, or cervical erosion. Since there is evidence that presence of the trichomonad can interfere with accurate assessment of abnormal cytological smears, additional smears should be performed after eradication of the parasite.

Treatment of Asymptomatic Sexual Partners.

T. vaginalis

infection is a venereal disease. Therefore, asymptomatic sexual partners of treated patients should be treated simultaneously if the organism has been found to be present, in order to prevent reinfection of the partner. The decision as to whether to treat an asymptomatic male partner who has a negative culture or one for whom no culture has been attempted is an individual one. In making this decision, it should be noted that there is evidence that a woman may become reinfected if her sexual partner is not treated. Also, since there can be considerable difficulty in isolating the organism from the asymptomatic male carrier, negative smears and cultures cannot be relied upon in this regard. In any event, the sexual partner should be treated with metronidazole in cases of reinfection.

Amebiasis.

Metronidazole is indicated in the treatment of acute intestinal amebiasis (amebic dysentery) and amebic liver abscess. In amebic liver abscess, metronidazole therapy does not obviate the need for aspiration or drainage of pus.

Anaerobic Bacterial Infections.

Metronidazole is indicated in the treatment of serious infections caused by susceptible anaerobic bacteria. Indicated surgical procedures should be performed in conjunction with metronidazole therapy. In a mixed aerobic and anaerobic infection, antimicrobials appropriate for the treatment of the aerobic infection should be used in addition to metronidazole.

INTRA-ABDOMINAL INFECTIONS, including peritonitis, intra-abdominal abscess, and liver abscess, caused by Bacteroides species including the

B. fragilis

group (

B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron, B. vulgatus

Clostridium

species,

Eubacterium

species,

Peptococcus

species, and

Peptostreptococcus

species.

SKIN AND SKIN STRUCTURE INFECTIONS caused by

Bacteroides

species including the

B. fragilis

group,

Clostridium

species,

Peptococcus

species,

Peptostreptococcus

species, and

Fusobacterium

species.

GYNECOLOGIC INFECTIONS, including endometritis, endomyometritis, tubo-ovarian abscess, and postsurgical vaginal cuff infection, caused by

Bacteroides

species including the

B. fragilis

group,

Clostridium

species,

Peptococcus

species,

Peptostreptococcus

species, and

Fusobacterium

species.

BACTERIAL SEPTICEMIA caused by

Bacteroides

species including the

B. fragilis

group and

Clostridium

species.

BONE AND JOINT INFECTIONS, (as adjunctive therapy), caused by

Bacteroides

species including the

B. fragilis

group.

CENTRAL NERVOUS SYSTEM (CNS) INFECTIONS, including meningitis and brain abscess, caused by

Bacteroides

species including the

B. fragilis

group.

LOWER RESPIRATORY TRACT INFECTIONS, including pneumonia, empyema, and lung abscess, caused by

Bacteroides

species including the

B. fragilis

group.

ENDOCARDITIS caused by

Bacteroides

species including the

B. fragilis

group.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of metronidazole and other antibacterial drugs, metronidazole should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Trichomoniasis:

In the Female:

One-day treatment

– two grams of metronidazole, given either as a single dose or in two divided doses of one gram each, given in the same day.

Seven-day course of treatment

– 250 mg three times daily for seven consecutive days. There is some indication from controlled comparative studies that cure rates as determined by vaginal smears and signs and symptoms, may be higher after a seven-day course of treatment than after a one-day treatment regimen.

The dosage regimen should be individualized. Single-dose treatment can assure compliance, especially if administered under supervision, in those patients who cannot be relied on to continue the seven-day regimen.

A seven-day course of treatment may minimize reinfection by protecting the patient long enough for the sexual contacts to obtain appropriate treatment. Further, some patients may tolerate one treatment regimen better than the other.

Pregnant patients should not be treated during the first trimester (see

CONTRAINDICATIONS

). In pregnant patients for whom alternative treatment has been inadequate, the one-day course of therapy should not be used, as it results in higher serum levels which can reach the fetal circulation (see

PRECAUTIONS, Pregnancy

). When repeat courses of the drug are required, it is recommended that an interval of four to six weeks elapse between courses and that the presence of the trichomonad be reconfirmed by appropriate laboratory measures. Total and differential leukocyte counts should be made before and after re-treatment.

In the Male: Treatment should be individualized as it is for the female.

The following reactions have been reported during treatment with metronidazole:

Central Nervous System

The most serious adverse reactions reported in patients treated with metronidazole have been convulsive seizures, encephalopathy, aseptic meningitis, optic and peripheral neuropathy, the latter characterized mainly by numbness or paresthesia of an extremity. Since persistent peripheral neuropathy has been reported in some patients receiving prolonged administration of metronidazole, patients should be specifically warned about these reactions and should be told to stop the drug and report immediately to their physicians if any neurologic symptoms occur. In addition, patients have reported headache, syncope, dizziness, vertigo, incoordination, ataxia, confusion, dysarthria, irritability, de-pression, weakness, and insomnia (see

WARNINGS

Gastrointestinal

The most common adverse reactions reported have been referable to the gastrointestinal tract, particularly nausea, sometimes accompanied by headache, anorexia, and occasionally vomiting; diarrhea; epigastric distress; and abdominal cramping and constipation.

Mouth

A sharp, unpleasant metallic taste is not unusual. Furry tongue, glossitis, and stomatitis have occurred; these may be associated with a sudden overgrowth of

Candida

which may occur during therapy.

Dermatologic

Erythematous rash and pruritus.

Hematopoietic

Reversible neutropenia (leukopenia); rarely, reversible thrombocytopenia.

Cardiovascular

Flattening of the T-wave may be seen in electrocardiographic tracings.

Hypersensitivity

Urticaria, erythematous rash, Stevens-Johnson Syndrome, toxic epidermal necrolysis, flushing, nasal congestion, dryness of the mouth (or vagina or vulva), and fever.

Renal

Dysuria, cystitis, polyuria, incontinence, and a sense of pelvic pressure. Instances of darkened urine have been reported by approximately one patient in 100,000. Although the pigment which is probably responsible for this phenomenon has not been positively identified, it is almost certainly a metabolite of metronidazole and seems to have no clinical significance.

Other

Proliferation of

Candida

in the vagina, dyspareunia, decrease of libido, proctitis, and fleeting joint pains sometimes resembling “serum sickness.” Rare cases of pancreatitis, which generally abated on withdrawal of the drug, have been reported.

Patients with Crohn’s disease are known to have an increased incidence of gastrointestinal and certain extraintestinal cancers. There have been some reports in the medical literature of breast and colon cancer in Crohn’s disease patients who have been treated with metronidazole at high doses for extended periods of time. A cause and effect relationship has not been established. Crohn’s disease is not an approved indication for metronidazole tablets.

Metronidazole tablets, 250 mg or 500 mg is an oral formulation of the synthetic nitroimidazole antimicrobial, 2-methyl-5-nitro-1H-imidazole-1-ethanol, which has the following structural formula:

Referenced Image

Each tablet, for oral administration, contains 250 mg or 500 mg of metronidazole.

Inactive ingredients: colloidal silicon dioxide, crospovidone, magnesium stearate, microcrystalline cellulose, and stearic acid.

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