Metrodyl 200 mg/5 ml Suspension

Antibiotic and antiprotozoal for infections caused by anaerobic bacteria and protozoa:

• Amoebic dysentery and amoebic liver abscess
• Giardiasis
• Trichomoniasis and bacterial vaginosis
• Dental and gum infections
• Abdominal and pelvic infections, infections after surgery (often with other antibiotics)
• C. difficile diarrhoea (mild cases), H. pylori eradication (with other drugs)
• Surgical prophylaxis

Adults:

• Amoebic dysentery: 400–800 mg three times daily for 5–10 days.
• Giardiasis: 400 mg three times daily for 5 days (or 2 g once daily for 3 days).
• Trichomoniasis / bacterial vaginosis: 2 g single dose, or 400–500 mg twice daily for 5–7 days.
• Anaerobic infections: 400–500 mg every 8 hours; IV 500 mg every 8 hours.

Children: amoebiasis 35–50 mg/kg/day in 3 divided doses; other infections 7.5 mg/kg every 8 hours, as prescribed.

• Take tablets with or after food. Suspension (benzoate) is taken 1 hour before food.
• Do not drink alcohol during treatment and for 48 hours after.

• Allergy to metronidazole or other nitroimidazoles (tinidazole, ornidazole)
• Taking disulfiram in the last 2 weeks
• Alcohol use during treatment

Common: metallic taste, nausea, loss of appetite, stomach upset, dark urine (harmless), headache.

Less common: vomiting, diarrhoea, furred tongue, dizziness, rash.

Rare but serious: nerve damage (tingling or numbness of hands/feet) with long courses, seizures, confusion, severe skin reactions, liver problems (especially in Cockayne syndrome), low white cells.

• Severe reaction (flushing, vomiting, fast heartbeat) if taken with alcohol.
• Courses longer than 10 days need monitoring (nerves, blood counts).
• Lower dose in severe liver disease.
• May cause dizziness — take care when driving.

Avoid high single doses in pregnancy; standard courses may be used in the 2nd–3rd trimester when needed (and sometimes the 1st) on medical advice. Passes into breast milk and may change its taste — a single 2 g dose: stop breastfeeding for 12–24 hours.

• Alcohol and disulfiram (severe reactions)
• Warfarin (bleeding risk — monitor INR)
• Lithium, busulfan, ciclosporin, phenytoin, fluorouracil (levels rise)
• Phenobarbital, rifampicin (reduce metronidazole effect)

Nausea, vomiting, unsteadiness; seizures and nerve symptoms at very high doses. Treat symptoms.

Store below 30°C, away from light. Do not refrigerate the infusion.