Adults: For tablets and suspension, the dosing depends on the condition being treated. For trichomoniasis in adults and children over 10 years, the usual dose is 200 mg three times a day, or 400 mg twice a day, for 7 days; alternatively, 800 mg in the morning with 1 to 2 g at night for 2 days, or 2 g as a single dose for 1 day. For trichomoniasis in children, those aged 7 to 10 years take 100 mg three times a day, those aged 3 to 7 years take 100 mg twice a day, and those aged 1 to 3 years take 50 mg three times a day. For intestinal amoebiasis in adults and children over 10 years, the dose is 800 mg three times a day for 5 days. For intestinal amoebiasis in children, those aged 7 to 10 years take 400 mg three times a day, those aged 3 to 7 years take 200 mg four times a day, and those aged 1 to 3 years take 200 mg three times a day. For extra intestinal and asymptomatic amoebiasis in adults and children over 10 years, the dose is 400 to 800 mg three times a day for 5 to 10 days. For extra intestinal and asymptomatic amoebiasis in children, those aged 7 to 10 years take 200 to 400 mg three times a day, those aged 3 to 7 years take 100 to 200 mg four times a day, and those aged 1 to 3 years take 100 to 200 mg three times a day. For giardiasis in adults and children over 10 years, the dose is 2 g once daily for 3 days. For giardiasis in children, those aged 7 to 10 years take 1 g once daily, those aged 3 to 7 years take 600 to 800 mg once daily, and those aged 1 to 3 years take 500 mg once daily. For acute ulcerative gingivitis in adults and children over 10 years, the dose is 200 mg three times a day for 3 days. For acute ulcerative gingivitis in children, those aged 7 to 10 years take 100 mg three times a day, those aged 3 to 7 years take 100 mg twice a day, and those aged 1 to 3 years take 50 mg three times a day. For acute dental infections in adults and children over 10 years, the dose is 200 mg three times a day for 3 to 7 days. For bacterial vaginosis in adults and children over 10 years, the dose is 400 mg twice a day for 7 days, or 2 g as a single dose for 1 day. For leg ulcers and pressure sores in adults and children over 10 years, the dose is 400 mg three times a day for 7 days. For anaerobic infections in adults and children over 10 years, the dose is 800 mg initially, then 400 mg three times a day for 7 days. For anaerobic infections in children aged 1 to 10 years, the dose is 7.5 mg per kg three times a day. For surgical prophylaxis in adults and children over 10 years, the dose is 400 mg three times a day, started 24 hours before surgery, for 1 day. For surgical prophylaxis in children aged 1 to 10 years, the dose is 7.5 mg per kg three times a day.
For the vaginal gel, the recommended dose is one applicator full of Metronidazole gel, approximately 5 grams containing approximately 37.5 mg of Metronidazole, given intravaginally once or twice a day for 5 days. When used once a day, the gel should be applied at bedtime.
For suppositories used in anaerobic infections, adults take 1 g every 8 hours for 3 days, then 1 g every 12 hours. Children aged 5 to 10 years take 500 mg every 8 hours for 3 days, then every 12 hours; children over 10 years follow the adult dose. For surgical prophylaxis with suppositories, adults take 1 g 2 hours before surgery, with up to 3 further doses of 1 g given every 8 hours for high risk procedures. Children aged 5 to 10 years take 500 mg 2 hours before surgery, with up to 3 further doses of 500 mg given every 8 hours for high risk procedures.
For IV infusion, Metronidazole intravenous infusion requires no dilution and should not be mixed with any other drugs before administration. Adults and children over 12 years are infused with 500 mg every 8 hours at a rate of 5 ml per minute, and a maximum of 4 g should not be exceeded during a 24 hour period. Treatment for 7 days is sufficient for most patients, but treatment can be extended, especially where reinfection is likely. For surgical prophylaxis, a dose given shortly before surgery should be followed by doses every 8 hours for the next 24 hours. Children under 12 years are given 7.5 mg per kg of body weight per day, in doses every 8 hours, at a rate of 5 ml per minute.