What it's for (Indications)
- Metronidazole is indicated for the treatment of parasitic infections and bacterial infections, particularly anaerobic bacterial infections.
- It is also indicated in the treatment of inflammatory papules and pustules of rosacea, a chronic facial condition characterized by acne and redness.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | Use this medicine exactly as advised by your doctor; do not alter your dosage without a doctor’s approval. For the treatment of anaerobic bacterial infections in adults, the recommended dosage schedule involves a loading dose of 15 mg/kg infused over one hour (approximately 1 g for a 70-kg adult), followed by a maintenance dose of 7.5 mg/kg infused over one hour every six hours (approximately 500 mg for a 70-kg adult). The first maintenance dose should be instituted six hours following the initiation of the loading dose. Parenteral therapy may be changed to oral metronidazole therapy when conditions warrant, with the usual adult oral dosage being 7.5 mg/kg every six hours. A maximum of 4 grams should not be exceeded during a 24-hour period. The usual duration of therapy is 7 to 10 days; however, infections may require longer treatment. Do not exceed the recommended daily dose or use for longer than prescribed without a doctor’s approval. |
Safety & Warnings
Common Side Effects
- Serious adverse reactions include convulsive seizures, encephalopathy, aseptic meningitis, optic neuropathy, and peripheral neuropathy (characterized mainly by numbness, paresthesia, or tingling sensation of an extremity).
- Other reported side effects include agitation, blurred vision, confusion, dizziness, and headache.
- Gastrointestinal adverse effects include nausea, anorexia, vomiting, abdominal discomfort, diarrhea, an unpleasant or sharp metallic taste, epigastric distress, abdominal cramping, constipation, and pancreatitis.
- Oral manifestations like furry tongue, glossitis, and stomatitis have been reported.
- Local irritation and pruritus (localized or generalized itching) may also occur.
Serious Warnings
- Black Box Warning: WARNING Metronidazole has been shown to be carcinogenic in mice and rats. Its use, therefore, should be reserved for the conditions described in the indications for use.
- Patients taking this medication must be cautious and avoid contact with eyes.
- Caution is advised in cases of severe hepatic (liver) damage, dyshematopoiesis (abnormal formation of red blood cells), and CNS (Central nervous system) disorders.
- Inform your doctor about your complete medical history before using this medicine.
- Consult a doctor before using other antibiotics concurrently.
- Discontinue consumption of alcohol or products containing propylene glycol during and for at least three days after therapy with metronidazole, as it can cause a disulfiram-like reaction including abdominal cramps, nausea, vomiting, headaches, and flushing.
- Do not exceed the recommended daily dose.
- Do not use for longer than it is prescribed without a doctor’s approval.
- Do not alter your dosage without a doctor’s approval.
- If this medicine does not suit you, then stop using it immediately.
- Store at room temperature away from direct heat and sunlight.
- Keep it out of the reach of children and pets.
- Do not use after its expiry date or if the quality seal is broken or missing.
How it Works (Mechanism of Action)
Metronidazole, a nitroimidazole, exerts antibacterial effects in an anaerobic environment against most obligate anaerobes. Once metronidazole enters the organism by passive diffusion and is activated in the cytoplasm of susceptible anaerobic bacteria, it is reduced. This process includes intra-cellular electron transport donors such as ferredoxin and transfer of an electron to the nitro group of metronidazole, leading to the formation of a short-lived nitroso free radical. Because of this alteration of the metronidazole molecule, a concentration gradient is created and maintained which promotes the drug's intracellular transport. The reduced form of metronidazole and free radicals may interact with DNA leading to inhibition of DNA synthesis, DNA degradation, and death of bacteria. The precise mechanism of action of metronidazole is unclear.