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Indications/Uses
For the treatment of asymptomatic and symptomatic trichomoniasis, infections due to susceptible anaerobic bacteria, intestinal and hepatic amoebiasis and giardiasis.
Dosage/Direction for Use
Trichomoniasis: Adult: Given orally either as a single 2 g dose, as a 2-day course of 800 mg in the morning and 1.2 g in the evening, as a 7-day course of 600 mg to 1 g daily in two or three divided doses.
Anaerobic bacterial infections: Given orally in an initial dose of 800 mg followed by 400 mg every 8 hours, usually for about 7 days.
Amoebiasis: Adult: Given in oral doses of 400 to 800 mg three times daily for 5 to 10 days. An alternative adult dose is 1.5 to 2.5 g as a single daily dose for 2 to 3 days.
Children: Aged 1 to 3 years may be given one-quarter, those aged 3 to 7 years one-third, and those aged 7 to 10 years one-half the total adult daily dose; alternatively 35 to 50 mg/kg in divided doses.
Giardiasis: Adult: Usual oral dose is 2 g once daily for 3 successive days, or 400 mg three times daily for 5 days, or 500 mg twice daily for 7 to 10 days.
Children: Alternative schedule for children is 15 mg/kg daily in divided doses.
Anaerobic bacterial infections: Given orally in an initial dose of 800 mg followed by 400 mg every 8 hours, usually for about 7 days.
Amoebiasis: Adult: Given in oral doses of 400 to 800 mg three times daily for 5 to 10 days. An alternative adult dose is 1.5 to 2.5 g as a single daily dose for 2 to 3 days.
Children: Aged 1 to 3 years may be given one-quarter, those aged 3 to 7 years one-third, and those aged 7 to 10 years one-half the total adult daily dose; alternatively 35 to 50 mg/kg in divided doses.
Giardiasis: Adult: Usual oral dose is 2 g once daily for 3 successive days, or 400 mg three times daily for 5 days, or 500 mg twice daily for 7 to 10 days.
Children: Alternative schedule for children is 15 mg/kg daily in divided doses.
Overdosage
Single oral doses of metronidazole, up to 12 g, have been reported in suicide attempts and accidental overdoses. Symptoms reported include nausea, vomiting, and ataxia. Oral metronidazole has been studied as a radiation sensitizer on the treatment of malignant tumors. Neurotoxic effects including seizures and peripheral neuropathy have been reported after 5 to 7 days of doses of 6 to 10.4 g every other day.
Treatment: There is no specific antidote for metronidazole overdose; therefore, management of the patient should consist of symptomatic and supportive therapy.
Treatment: There is no specific antidote for metronidazole overdose; therefore, management of the patient should consist of symptomatic and supportive therapy.
Administration
Should be taken with food.
Contraindications
Patients with a prior history of hypersensitivity to metronidazole or other nitroimidazole derivatives. Patients with history or evidence of blood dyscrasia. In patients with trichomoniasis, metronidazole is contraindicated during the first trimester of pregnancy.
Warnings
Metronidazole has been shown to be carcinogenic in mice and possibly carcinogenic in rats.
Unnecessary use of the drug should be avoided.
Unnecessary use of the drug should be avoided.
Special Precautions
Patients should be monitored for neurological sign, Candida overgrowth may occur; interacts with alcohol and warfarin.
As much as possible, its use should be avoided in pregnancy.
As much as possible, its use should be avoided in pregnancy.
Use In Pregnancy & Lactation
Use in Pregnancy: Metronidazole should not be given in the first trimester of pregnancy as it crosses the placenta and enters fetal circulation rapidly.
Use in Lactation: Metronidazole is secreted in breast milk. In view of its tumorigenic and mutagenic potential, breastfeeding is not recommended.
Use in Lactation: Metronidazole is secreted in breast milk. In view of its tumorigenic and mutagenic potential, breastfeeding is not recommended.
Adverse Reactions
The adverse effects of metronidazole are generally dose-related. The most common are gastrointestinal disturbances especially nausea and an unpleasant metallic taste. Vomiting and diarrhea or constipation may also occur. A furred tongue, glossitis, and stomatitis may be associated with an overgrowth of Candida. There have been rare reports of antibiotic-associated colitis associated with metronidazole, although it is also used in the treatment of this condition.
Weakness, dizziness, ataxia, headache, drowsiness, insomnia, and change in mood or mental state such as depression or confusion have also been reported. Peripheral neuropathy, usually presenting as numbness or tingling in the extremities, and epileptic seizures have been associated with high doses of metronidazole or prolonged treatment.
Temporary moderate leucopenia and thrombocytopenia may occur in some patients receiving metronidazole. Skin rashes, urticaria, and pruritus occur occasionally and erythema multiform, angioedema and anaphylaxis have been reported rarely. Other adverse effects include urethral discomfort and darkening of the urine. Raised liver enzyme values, cholestatic hepatitis, and jaundice have occasionally been reported.
Thrombophlebitis may follow the intravenous administration of metronidazole.
Studies have shown metronidazole to be mutagenic in bacteria and carcinogenic in some animals.
Weakness, dizziness, ataxia, headache, drowsiness, insomnia, and change in mood or mental state such as depression or confusion have also been reported. Peripheral neuropathy, usually presenting as numbness or tingling in the extremities, and epileptic seizures have been associated with high doses of metronidazole or prolonged treatment.
Temporary moderate leucopenia and thrombocytopenia may occur in some patients receiving metronidazole. Skin rashes, urticaria, and pruritus occur occasionally and erythema multiform, angioedema and anaphylaxis have been reported rarely. Other adverse effects include urethral discomfort and darkening of the urine. Raised liver enzyme values, cholestatic hepatitis, and jaundice have occasionally been reported.
Thrombophlebitis may follow the intravenous administration of metronidazole.
Studies have shown metronidazole to be mutagenic in bacteria and carcinogenic in some animals.
Drug Interactions
When given with alcohol, metronidazole may provoke a disulfiram-like reaction in some patients. Acute psychosis or confusion have been associated with the use of metronidazole and disulfiram together.
Metronidazole is reported to impair the metabolism or excretion of several drugs including warfarin and phenytoin, lithium, ciclosporin, and fluorouracil, with the consequent potential for an increased incidence of adverse effects. Plasma concentrations of metronidazole are decreased by phenobarbital, with a consequent reduction in the effectiveness of metronidazole. Cimetidine has increased plasma concentration of metronidazole and might increase the risk of neurological adverse effects.
Metronidazole is reported to impair the metabolism or excretion of several drugs including warfarin and phenytoin, lithium, ciclosporin, and fluorouracil, with the consequent potential for an increased incidence of adverse effects. Plasma concentrations of metronidazole are decreased by phenobarbital, with a consequent reduction in the effectiveness of metronidazole. Cimetidine has increased plasma concentration of metronidazole and might increase the risk of neurological adverse effects.
Storage
Store at temperatures not exceeding 30°C.
Action
Pharmacology: Actions: Specific bactericidal activity against important obligate anaerobes.
Pharmacokinetics: Metronidazole is readily and most completely absorbed after oral doses. Peak plasma concentrations of about 6 and 12 micrograms/mL are achieved, usually within 1 to 2 hours, after single doses of 250 and 500 mg respectively. Some accumulation occurs and consequently there are higher concentrations when multiple doses are given. Absorption may be delayed but is not reduced overall by food. Metronidazole benzoate given by mouth is hydrolyzed in the gastrointestinal tract to release metronidazole which in turn is then absorbed.
Metronidazole is widely distributed. It appears in most body tissues and fluids including bile, bone, breast milk, cerebral abscesses, CSF, liver and liver abscesses, saliva, seminal fluids, and vaginal secretions, and achieves concentration similar to those in plasma. It also crosses the placenta and rapidly enters the fetal circulations. No more than 20% is bound to plasma proteins.
The elimination half-life of metronidazole is about 8 hours; that of the hydroxy metabolite is slightly longer. The half-life of metronidazole is reported to be longer in neonates and in patients with severe hepatic impairment; that of the hydroxy metabolite is prolonged in patients with substantial renal impairment. The majority of a dose of metronidazole is excreted in the urine, mainly as metabolites; a small amount appears in the feces.
Pharmacokinetics: Metronidazole is readily and most completely absorbed after oral doses. Peak plasma concentrations of about 6 and 12 micrograms/mL are achieved, usually within 1 to 2 hours, after single doses of 250 and 500 mg respectively. Some accumulation occurs and consequently there are higher concentrations when multiple doses are given. Absorption may be delayed but is not reduced overall by food. Metronidazole benzoate given by mouth is hydrolyzed in the gastrointestinal tract to release metronidazole which in turn is then absorbed.
Metronidazole is widely distributed. It appears in most body tissues and fluids including bile, bone, breast milk, cerebral abscesses, CSF, liver and liver abscesses, saliva, seminal fluids, and vaginal secretions, and achieves concentration similar to those in plasma. It also crosses the placenta and rapidly enters the fetal circulations. No more than 20% is bound to plasma proteins.
The elimination half-life of metronidazole is about 8 hours; that of the hydroxy metabolite is slightly longer. The half-life of metronidazole is reported to be longer in neonates and in patients with severe hepatic impairment; that of the hydroxy metabolite is prolonged in patients with substantial renal impairment. The majority of a dose of metronidazole is excreted in the urine, mainly as metabolites; a small amount appears in the feces.
MedsGo Class
Other Antibiotics
Features
Dosage
500 mg
Ingredients
- Metronidazole
Packaging
Tablet 100's
Generic Name
Metronidazole
Registration Number
DRP-2420-02
Classification
Prescription Drug (RX)
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