What is the use of Metronidazole (Flagyl)?

From the Guidelines

Metronidazole is the primary treatment for trichomoniasis, with a recommended dose of 2 g orally in a single dose or 500 mg orally twice daily for 7 days, as evidenced by the most recent guideline 1.

Overview of Metronidazole

Metronidazole is an antibiotic medication used to treat infections caused by anaerobic bacteria and certain parasites. It is effective against conditions like bacterial vaginosis, trichomoniasis, giardiasis, amoebiasis, and anaerobic bacterial infections including Clostridium difficile colitis.

Dosage and Administration

The dosage of metronidazole varies depending on the specific infection being treated. For trichomoniasis, the recommended dose is 2 g orally in a single dose or 500 mg orally twice daily for 7 days, as stated in the guideline 1. For bacterial vaginosis, the recommended dose is 500 mg orally twice daily for 7 days or metronidazole gel 0.75% intravaginally once daily for 5 days 1.

Mechanism of Action and Side Effects

Metronidazole works by disrupting DNA synthesis in susceptible organisms. Common side effects include metallic taste, nausea, and darkened urine. Patients should avoid alcohol completely during treatment and for at least 48 hours afterward to prevent a disulfiram-like reaction that can cause severe nausea, vomiting, flushing, and headache.

Importance of Completing the Full Course

The full course of metronidazole should always be completed even if symptoms improve before finishing treatment to prevent antibiotic resistance and ensure complete eradication of the infection. This is crucial in ensuring the effectiveness of the treatment and preventing the development of resistant strains of bacteria.

Treatment of Sex Partners

Treatment of sex partners is also important in preventing the transmission of trichomoniasis, as stated in the guidelines 1 and 1. Ensuring treatment of sex partners can increase the cure rate and prevent reinfection.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain the effectiveness of metronidazole tablets and other antibacterial drugs, metronidazole tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. Prescribing metronidazole tablets in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of development of drug-resistant bacteria.

Metronidazole should be used to treat bacterial infections that are proven or strongly suspected to be caused by bacteria. The medication should not be prescribed without a proven or strongly suspected bacterial infection, as this may increase the risk of developing drug-resistant bacteria. Key points to consider when using metronidazole include:

• Use only for proven or strongly suspected bacterial infections
• Avoid use in patients without a bacterial infection or prophylactic indication
• Risk of developing drug-resistant bacteria if used unnecessarily 2 2

From the Research

Metronidazole Overview

• Metronidazole is an antibiotic used to treat various infections, including protozoal and anaerobic infections 3, 4, 5.
• It is effective against Trichomonas infection, amebiasis, giardiasis, and anaerobic infections 3, 4, 5.
• Metronidazole is well tolerated, but adverse reactions can occur, including reversible neutropenia, peripheral neuropathy, and disulfiram-like reaction when taken with alcohol 4, 5.

Pharmacokinetics and Pharmacodynamics

• Metronidazole is absorbed almost completely after oral administration and has a limited plasma protein binding 4.
• It has a half-life of 6 to 10 hours and is extensively metabolized by the liver to form 5 oxidative metabolites 4.
• Metronidazole diffuses well into all tissues and penetrates the central nervous system well 5.

Clinical Applications and Dose Regimens

• Metronidazole is currently approved for use against Trichomonas infection and amebiasis 5.
• It is also effective against giardiasis, "nonspecific vaginitis," and anaerobic infections 5.
• The recommended dose is 500 mg three times per day, and an adaptation is necessary in renal insufficiency 4.
• Metronidazole should only be used for approved indications, except in the research setting, and should not be used prophylactically 5.

Comparison with Tinidazole

• Tinidazole is a structural analogue of metronidazole and has been shown to be equivalent and often superior to metronidazole in the treatment of trichomoniasis and giardiasis 3, 6.
• Tinidazole has a longer plasma half-life than metronidazole and is minimally bound to plasma protein 3, 6.
• Tinidazole is effective against a wide range of clinically significant anaerobic bacteria and has been shown to be effective in the treatment of amebiasis and amebic liver abscess 6.