Anti protozoal and antimicrobial drug, a derivative of 5nitroimidazole. The mechanism of action is to restore the biochemical 5 – nitrogroup intracellular transport proteins anaerobic bacteria and protozoa.


Each 100 ml contains: metronidazole USP – 500 mg

Indications for use

  • Protozoal infections
  • Extraintestinal amebiasis, including amebic liver abscess
  • Intestinal amebiasis (amebic dysentery)
  • Trichomoniasi, trichomonas vaginitis, trichomonas urethritis
  • Infections, caused by Bacteroides spp. (including Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides vulgatus)
  • Bone and joint infections
  • Infections of the CNS, including meningitis
  • Brain abscess
  • Bacterial endocarditis
  • Pneumonia, lung abscess
  • Empyema
  • Sepsis
  • Infections, caused by species of Clostridium spp., Peptococcus niger and Peptostreptococcus spp.
  • Infections, of the abdomen (peritonitis, abscess of the liver)
  • Pelvic infections (endometritis, abscess of the fallopian tubes and ovaries, infection of vaginal vault)
  • Pseudomembranous colitis (associated with the use of antibiotics)
  • Gastritis or duodenal ulcer associated with Helicobacter pylori
  • Prophylaxis of postoperative complications (especially intervention colon, adrectal area, appendectomy, gynecological surgery)
  • Radiation therapy of patients with tumors – as a radio sensitizing drug in cases where resistance is due to tumor hypoxia in tumor cells.

Mode of administration

Metral infusion should be infused intravenously at an approximate rate of 5 ml/min. Oral medication should be substituted as soon as feasible.

Prophylaxis against anaerobic infection: Chiefly in the context of abdominal (especially colorectal) and gynaecological surgery. Adults: 500mg shortly before operation, repeated 8 hourly. Oral doses of 200 mg or 400 mg 8 hourly to be started as soon as feasible.

Children: Children < 12 years: 20-30mg/kg as a single dose given 1-2 hours before surgery. Newborns with a gestation age < 40 weeks: 10mg/kg body weight as a single dose before operation.

Anaerobic Infections: Treatment for seven days should be satisfactory for most patients but, depending upon clinical and bacteriological assessments, the physician might decide to prolong treatment e.g. for the eradication of infection from sites which cannot be drained or are liable to endogenous recontamination by anaerobic pathogens from the gut, oropharynx or genital tract. Treatment of established anaerobic infections: Intravenous route is to be used initially if patient’s symptoms preclude oral therapy.

Adults: 500 mg 8 hourly. Children: Children > 8 weeks to 12 years of age: The usual daily dose is 20-30mg/kg/day as a single dose or divided into 7.5mg/kg every 8 hours. The daily dose may be increased to 40mg/kg, depending on the severity of the infection. Duration of treatment is usually 7 days.

Children < 8 weeks of age: 15mg/kg as a single dose daily or divided into 7.5mg/kg every 12 hours. In newborns with a gestation age < 40 weeks, accumulation of metronidazole can occur during the first week of life, therefore the concentrations of metronidazole in serum should preferable be monitored after a few days therapy.

Bacterial vaginosis: Adolescents: 400mg twice daily for 5-7 days or 2000mg as a single dose. Urogenital trichomoniasis: Adults and adolescents: 2000mg as a single dose or 200mg 3 times daily for 7 days or 400mg twice daily for 5-7 days Children < 10 years: 40mg/kg orally as a single dose or 1530 mg/kg/day divided in 2-3 doses for 7 days; not to exceed 2000mg/dose Giardiasis: > 10 years: 2000mg once daily for 3 days, or 400mg three times daily for 5 days, or 500mg twice daily for 7 to 10 days.

Children 7 to 10 years: 1000mg once daily for 3 days. Children 3 to 7 years: 600 to 800mg once daily for 3 days. Children 1 to 3 years: 500mg once daily for 3 days. Alternatively, as expressed in mg per kg of body weight: 1540mg/kg/day divided in 2-3 doses.

Amoebiasis: > 10 years: 400 to 800mg 3 times daily for 5-10 days.

Children 7 to 10 years: 200 to 400mg 3 times daily for 5-10 days. Children 3 to 7 years: 100 to 200mg 4 times daily for 5-10 days.

Children 1 to 3 years: 100 to 200mg 3 times daily for 5-10 days. Alternatively, doses may be expressed by body weight: 35 to 50mg/kg daily in 3 divided doses for 5 to 10 days, not to exceed 2400mg/day Eradication of Helicobacter pylori in paediatric patients: As a part of a combination therapy, 20mg/kg/day not to exceed 500mg twice daily for 7-14 days.

Official guidelines should be consulted before initiating therapy.

Elderly: Caution is advised in the elderly. Particularly at high doses although there is limited information available on modification of dosage.