Metronidazole is a nitroimidazole antibiotic and antiprotozoal agent, primarily used to treat anaerobic bacterial and protozoal infections. The 200mg/5ml oral suspension formulation is particularly suited for pediatric and geriatric patients, or those with difficulty swallowing tablets. It is bactericidal and amebicidal, with excellent tissue penetration.
Adult: Amoebiasis: 400-800 mg TDS for 5-10 days. Anaerobic infections: 400 mg TDS for 7-10 days. Trichomoniasis/Giardiasis: 2g single dose or 400 mg TDS for 7 days. *H. pylori*: 400-500 mg BD/TDS as part of regimen.
Note: Shake the bottle well before use. Use the measuring cup/spoon provided. Can be taken with or after food to minimize GI upset. Complete the full prescribed course.
Metronidazole is a prodrug. Its nitro group is reduced by low-redox-potential electron transport proteins (ferredoxin or flavodoxin) found in anaerobic bacteria and protozoa. This reduction forms short-lived, cytotoxic nitro radical anions that damage microbial DNA, leading to strand breaks and inhibition of nucleic acid synthesis.
Pregnancy: Category B (US FDA). Contraindicated in first trimester for trichomoniasis. Use in second/third trimester only if potential benefit justifies risk. Crosses placenta.
Driving: May cause dizziness, vertigo, ataxia, or confusion. Patients should be cautioned about operating machinery or driving until their response is known.
| Alcohol/Beverages/Medicines containing alcohol | Disulfiram-like reaction (flushing, headache, nausea, vomiting, tachycardia) | Major |
| Warfarin and other coumarin anticoagulants | Increased anticoagulant effect, elevated INR, risk of bleeding | Major |
| Lithium | Increased lithium levels and risk of toxicity | Major |
| Phenytoin, Phenobarbital | Increased metabolism of metronidazole, reducing its efficacy | Moderate |
| Cimetidine | Increased metronidazole levels (inhibits metabolism) | Moderate |
| 5-Fluorouracil | Potential increased toxicity of 5-FU | Moderate |