| Indication | For the treatment of anaerobic infections and mixed infections, surgical prophylaxis requiring anaerobic coverage, Clostridium difficile-associated diarrhea and colitis, Helicobacter pylori infection and duodenal ulcer disease, bacterial vaginosis, Giardia lamblia gastro-enteritis, amebiasis caused by Entamoeba histolytica, acne rosacea (topical treatment), and Trichomonas infections. |
| Pharmacodynamics | Metronidazole, a synthetic antibacterial and antiprotozoal agent of the nitroimidazole class, is used against protozoa such as Trichomonas vaginalis, amebiasis, and giardiasis. Metronidazole is extremely effective against anaerobic bacterial infections and is also used to treat Crohn's disease, antibiotic-associated diarrhea, and rosacea. |
| Mechanism of action | Metronidazole is a prodrug. Unionized metronidazole is selective for anaerobic bacteria due to their ability to intracellularly reduce metronidazole to its active form. This reduced metronidazole then covalently binds to DNA, disrupt its helical structure, inhibiting bacterial nucleic acid synthesis and resulting in bacterial cell death. |
| Absorption | Well absorbed (at least 80%) with peak plasma concentrations achieved in 1-3 hours following oral administration of therapeutic doses of immediate release formulation. |
| Volume of distribution | Not Available |
| Protein binding | Less than 20% bound to plasma proteins. |
| Metabolism | Hepatic metabolism by hydroxylation, oxidation, and glucuronidation. |
| Route of elimination | Not Available |
| Half life | 6-8 hours |
| Clearance | Not Available |
| Toxicity | LD50=500 mg/kg/day (orally in rat). Adverse effects include reversible peripheral neuropathy with prolonged therapy, CNS toxicity, disulfiram effect with alcohol, dark red-brown urine, metallic taste, nausea, epigastric distress, dizziness, vertigo and paresthesias associated with high doses, and neutropenia (reversible and mild). |