Drug Groups

approved

Description

A nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections. It has also been proposed as a radiation sensitizer for hypoxic cells. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985, p133), this substance may reasonably be anticipated to be a carcinogen (Merck, 11th ed).

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.

Pharmacology

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.

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).

Affected Organisms

Biotransformation

Hepatic metabolism by hydroxylation, oxidation, and glucuronidation.

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.

Half Life

6-8 hours

Protein Binding

Less than 20% bound to plasma proteins.

References

External Links