Metronidazole is a 5-nitroimidazole derivative with activity against protozoa and anaerobic bacteria. In amoebiasis, metronidazole acts as an amoebicide at all sites of infection with Entamoeba histolytica. Because of its rapid absorption it is probably less effective against parasites in the bowel lumen and is therefore used in conjunction with a luminal amoebicide such as diloxanide furoate or di-iodohydroxyquinoline in the treatment of amoebic dysentery and in extra-interstinal amoebiasis, including hepatic amoebiasis.

Tinidazole has the antimicrobial actions of metronidazole and usually administered as a single dose by mouth with or without food.

Metronidazole

Tablet, 250mg
Syrup 4% w/v, 250mg/5ml
Suspension (oral), 125mg/5ml
Intravenous infusion, 5mg/ml in 100ml

Indications: invasive amoebiasis and giardiasis, trichomoniasis, tissue nematode infections, bacterial infections (section 7.1.2); Helicobacter pylori eradication.

Cautions, Drug interactions, Contraindications, Side effects -see section 7.1.2 under metronidazole.

Dose and Administration

Invasive amoebiasis, by mouth, Adult and Child 30mg/kg daily in 3 divided doses for 8 - 10 days; subsequent course of luminal amoebicide.

Invasive amoebiasis; (if oral administration not possible), by intravenous infusion, Adult and patient able to complete course with oral drugs), subsequent course of luminal amoebicide.

Giardiasis, by mouth, Adult 2g once daily for 3 days, child 15mg/kg daily in divided doses for 5 - 10 days.

Storage - at room temperature, in a well closed, light resistant container.

Tinidazole

Tablet, 150mg, 500mg

Indications: - in the treatment of susceptible protozoal infections and in the treatment and prophylaxis of anaerobic bacterial infections.

Cautions: - see under metronidazole; avoid porphyria

Drug interactions: - alcohol

Side effects: - see under metronidazole

Dose and Administration: Oral

Intestinal amoebiasis, 2gm daily for 2 - 3 days; CHILD 50 - 60 mg/kg daily for 3 days

Amoebic involvement of liver, 1.5 - 2gm daily for 3 - 6 days, CHILD 50 - 60mg/kg daily for 5 days.

Giardiasis, single 2gm dose; CHILD single dose of 50 - 75 mg/kg (repeated once if necessary)

Diloxanide Furoate

Tablet, 500mg

Indications: - chronic amoebiasis, intestinal amoebiasis. It is a drug of choice for asymptomatic patients with E.histolytica cysts in the faces.

Side effects - flatulence, vomiting, urticaria, pruritus

Dose and Administration: -

Adult - oral, 500mg 3 times daily for 10 days
Child - oral, 20mg daily in 3 divided doses