The drug metronidazole is a broad-spectrum antibiotic that is used in the treatment of a wide variety of bacterial and protozoal infections. The appropriate dose varies considerably according to the condition being treated and the age of the patient as well as his or her level of kidney and liver function. Since serious side effects may develop from the use of this medication, including encephalopathy, peripheral and optic neuropathy, convulsions, aseptic meningitis, brain lesions and cancer, the lowest possible metronidazole dose should be administered.
A wide variety of medical conditions are caused by amoebic infections, the majority of which may be treated by this medication. The standard adult metronidazole dose for amebiasis is between 500 and 750 mg administered orally, three times daily for a period lasting between five and ten days. Infants and young children should instead use 35 to 50 mg/kg in three divided oral doses each day.
Trichomoniasis may also be treated using metronizadole. In adults, a dose of 500 mg may be taken for a period of one week. Alternatively, a single dose of 2 g may be given. Children and adolescents should receive 15 to 30 mg/kg in three divided doses every eight hours for a period of one week. The patient's sexual partner should also be tested and treated to prevent reinfection.
When treating pseudomembranous colitis, a lower metronidazole dose of between 250 and 500 mg can be given. The medication should be taken between three to four times daily. Treatment should be continued for a period of 10 to 14 days. Pediatric patients should receive 20 mg/kg daily in four divided doses every six hours. No more than 2 g per day should be given to pediatric patients.
When treating either dracunculiasis or giardia, a metronidazole dose of 250 mg should be given orally every eight hours. In dracuncliasis, the course of treatment lasts ten days on average. Giardiasis may require as few as seven days of treatment, although the duration of treatment may be extended in serious cases if needed.
In ulcerative conditions caused by infections of Heliobacter pylori, metronizadole may be effective. An oral dose of 250 mg should be given every six hours. The average length of therapy for the effective treatment of this condition is 14 days.
Metronizadole is also occasionally used for surgical prophylaxis, as in contaminated intestinal surgery, in order to prevent post-operative infection or sepsis. Prior to surgery, a metronizadole dose of 15 mg/kg should be given intravenously over 30 to 60 minutes, no later than an hour before surgery. A post-operative dose of 7.5 mg/kg over the same time period should be given after six and again 12 hours.
Lower doses should be used in elderly patients or those with diminished liver function, necessitating close monitoring of the level of the drug in the bloodstream when initiating treatment. Patients with severe renal insufficiency, which means having CrCl levels of less than 10 ml/min, should use half the recommended metronidazole dose. Since the drug is removed by dialysis, patients receiving this treatment may not need a dosage reduction.