Metronidazole
An antimicrobial taken by mouth for trichomoniasis and for anaerobic infections, and the treatment that the label says should also be given to the sexual partner.
- Class
- Nitroimidazole antimicrobial
- Sold as
- Sold as: Flagyl
- Prescription only
Boxed warning
- WARNING Metronidazole has been shown to be carcinogenic in mice and rats (see PRECAUTIONS). Unnecessary use of the drug should be avoided. Its use should be reserved for the conditions described in the INDICATIONS AND USAGE section below.
From the approved label
Metronidazole
- Approved uses
- Symptomatic Trichomoniasis Metronidazole tablets are 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 tablets are 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.
- Forms and strengths
- Metronidazole tablets, USP are available as follows: 250 mg - White, round, convex tablets debossed " PLIVA 333 " on one side and unscored on the other side.
- Must not be used when
- Hypersensitivity Metronidazole tablets are contraindicated in patients with a prior history of hypersensitivity to metronidazole or other nitroimidazole derivatives.
- In patients with trichomoniasis, metronidazole tablets are contraindicated during the first trimester of pregnancy (see PRECAUTIONS).
- Psychotic Reaction with Disulfiram Use of oral metronidazole is associated with psychotic reactions in alcoholic patients who were using disulfiram concurrently.
- Do not administer metronidazole to patients who have taken disulfiram within the last two weeks (see PRECAUTIONS, Drug Interactions).
- Warnings and precautions
- Hypersensitivity Reactions Hypersensitivity reactions including severe cutaneous adverse reactions (SCARs) can be serious and potentially life threatening (see ADVERSE REACTIONS).
- Severe Cutaneous Adverse Reactions Severe cutaneous adverse reactions (SCARs) including toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) have been reported with the use of metronidazole.
- Symptoms can be serious and potentially life threatening.
- If symptoms or signs of SCARs develop, discontinue metronidazole immediately and institute appropriate therapy.
- Common side effects
- 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.
- How it acts
- Microbiology Mechanism of Action Metronidazole, a nitroimidazole, exerts antibacterial effects in an anaerobic environment against most obligate anaerobes. Once metronidazole enters the organism by passive diffusion and activated in the cytoplasm of susceptible anaerobic bacteria, it is reduced; this process includes intracellular electron transport proteins such as ferredoxin, transfer of an electron to the nitro group of the metronidazole, and formation of a short-lived nitroso free radical.
- Label holder:
- Teva Pharmaceuticals USA, Inc.
- Label version:
This section reports the approved product information. The wording is condensed from the regulator's own summary, and the full document is linked under Sources.
Written by us
How it works
Metronidazole is taken up by organisms that survive without oxygen and damages their genetic material, which is why it works against trichomonas and anaerobic bacteria and not against the aerobic bacteria behind many other infections. That narrowness is the point: it is the reason the label names specific organisms rather than infection in general.
Original and generic
Off patent and inexpensive as a generic. Flagyl is the original brand; in Europe the generic is what is normally dispensed.
What it costs
Among the cheapest courses in this catalogue. In most European countries the medicine costs a fraction of the consultation that leads to it.
How to get it legally
Prescription only in Europe and the United States. The label makes one point that an online consultation has to handle honestly: for trichomoniasis it states that the sexual partner should be treated at the same time, which means the conversation cannot be only about the person filling in the form.
Questions
- What does the boxed warning say?
- The boxed warning records that metronidazole has been shown to be carcinogenic in mice and rats, and states that unnecessary use of the drug should be avoided. It is a warning about using it without an indication, not a statement about people who take a prescribed course.
- Why does the label mention treating the partner?
- Because trichomoniasis is sexually transmitted, and the label states plainly that the sexual partner should be treated as well. Treating only one of two people is how the infection returns.
- What about alcohol?
- The label addresses alcohol during treatment and for a period afterwards. The exact wording and the interval are in the label section on this page, and it is worth reading before rather than after the first drink.
Sources
- Metronidazole: prescribing informationDailyMed, US National Library of Medicine. Label version 16 July 2024
- Drugs@FDA: ANDA070027US Food and Drug Administration
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