Metronidazole is a drug effective against bacteria, amoeba and other protozoans like Trichomonas.
Mechanism of Action:
Metronidazole inhibits nucleic acid synthesis by disrupting DNA and causing strand breakage.
Metabolism:
The metabolism of Metronidazole is mainly in the liver. It is mainly excreted in the urine and a small proportion in the feces.
Indications for use and dosages:
- Anaerobic bacterial infections: In oral or dental infections, as a part of antibiotic regimen in sepsis, urogenital infections etc. Given intravenously 15mg/kg as loading dose and half of it as maintenance.
- In colorectal surgeries. Dosage is same as anaerobic infections.
- In hepatic encephalopathy suspected due to bacterial overgrowth, for gut sterilization.
- Bacterial vaginosis: Orally 500 mg twice daily for one week
- Amebiasis: 500-750 mg thrice daily for 5-10 days.
- Trichomonas: 250 mg thrice daily for one week
- Giardiasis: 500 mg twice a day for one week
- Pelvic Inflammatory Disease: 500 mg twice daily for 2 weeks with quinolones
- H.Pylori infection: 250-500 mg once daily for 2 weeks as a part of combination protocol.
- Inflammatory bowel disease: Crohns disease and ulcerative colitis.
Adverse Effects:
- Gastrointestinal: Nausea, vomiting, diarrhea, decreased appetite, metallic taste
- Neurological: headache, dizziness, ataxia, seizures, aseptic meningitis
- Allergy related: hypersensitivity, Steven Johnson syndrome, toxic epidermal necrolysis
- Hematological such as neutopenia
- Disulfiram like reaction to ethanol.
Interactions
Serious interactions are with drugs like Disulfiram, Cisapride, Erythromycin, Warfarin etc
Use in Pregnancy:
It is a category B drug in pregnancy, that is no significant teratogenicity found hence may be used if absolutely necessary
Use in Lactation:
It is secreted in milk hence not advisable during lactation.
Common brand names in India:
Flagyl, Metrogyl
