logo image

Metronidazole information from DrugsUpdate  

See Available Brands of Metronidazole in India

P - Contraindicated in pregnancy
L - Contraindicated in lactation
LI - Lab *

Metronidazole is a nitroimidazole anti-infective medication used mainly in the treatment of infections caused by susceptible organisms, particularly anaerobic bacteria and protozoa. It is marketed by Pfizer under the trade name Flagyl in the US, by Sanofi-Aventis globally under the same tradename, Flagyl, and by various generic manufacturers.

Metronidazole is also used as a gel preparation in the treatment of the dermatological conditions such as rosacea (Rozex and MetroGel by Galderma) and fungating tumours (Anabact, Cambridge Healthcare Supplies).

Pharmacodynamics

Pharmacokinetics

Metronidazole is converted to reduction products that interact with DNA to cause destruction of helical DNA structure and strand leading to a protein synthesis inhibition and cell death in susceptible organisms. It is effective against a wide range of organisms including E. histolytica, T. vaginalis, Giardia, anaerobes e.g. Bacterioides sp, Fusobacterium sp, Clostridium sp, Peptococcus sp and Peptostreptococcus sp, and moderately active against Gardnerella sp and Campylobacter sp.

Absorption
Readily absorbed from the GI tract (oral), poorly absorbed from the vagina (intravaginal); peak plasma concentrations after 1-2 hours (oral), 5-12 hours (rectal), 8 hours (intravaginal). May be delayed by the presence of food.

Distribution
Protein-binding: <20%. Widely distributed in body tissues and fluids e.g. bile, bone, breast milk, cerebral abscesses, CSF, liver and liver abscesses, saliva, semenal fluid, vaginal secretions (concentrations similar to those in plasma); crosses the placenta and rapidly enters fetal circulation.

Metabolism
Hepatic via side-chain oxidation and glucuronide formation.

Excretion

Mainly via urine (as metabolites); via faeces (small amounts). Elimination half-life: 8 hours; longer in neonates and severe hepatic impairment.

Metronidazole Indications / Metronidazole Uses

Information Not Available

Metronidazole Adverse Reactions / Metronidazole Side Effects

GI disturbances e.g. nausea, unpleasant metallic taste, vomiting, diarrhoea or constipation. Furred tongue, glossitis, and stomatitis due to overgrowth of Candida. Rarely, antibiotic-associated colitis. Weakness, dizziness, ataxia, headache, drowsiness, insomnia, changes in mood or mental state. Numbness or tingling in the extremities, epileptiform seizures (high doses or prolonged treatment). Transient leucopenia and thrombocytopenia. Hypersensitivity reactions. Urethral discomfort and darkening of urine. Raised liver enzyme values, cholestatic hepatitis, jaundice. Thrombophlebitis (IV).

Potentially Fatal: Anaphylaxis.

Precautions

Patients with severe hepatic disease metabolize Metronidazole slowly, with resultant accumulation of Metronidazole and its metabolites in the plasma. Accordingly, for such patients, doses below those usually recommended should be administered cautiously.

Known or previously unrecognized candidiasis may present more prominent symptoms during therapy with Metronidazole and requires treatment with a candidacidal agent.

Prescribing Metronidazole tablets in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

Overdosage
Symptoms: Nausea, vomiting, ataxia, seizures, peripheral neuropathy. Management: Symptomatic and supportive.

Special Precautions

Patients with CNS diseases; discontinue IV therapy if abnormal neurologic symptoms occur. History of seizure disorder. Evidence or a history of blood dyscrasias; perform total and differential leukocyte counts before and after treatment. Severe hepatic impairment; monitor plasma levels. Predisposition to oedema (inj contains sodium). Prolonged use may result in fungal or bacterial superinfection.

Other Drug Interactions

Acute psychoses or confusion with disulfiram. Additive/synergistic effect with other antimicrobials. Effects reduced with phenobarbital or phenytoin.

Potentially Fatal: Disulfiram-like reaction with alcohol. Increased risk of adverse effects of coumarin anticoagulants, phenytoin, lithium, ciclosporin, fluorouracil. Increased risk of neurological effects with cimetidine.

Other Interactions

Information Not Available

Dosage

Oral
Amoebiasis
Adult: 400-800 mg tid for 5-10 days or 1.5-2.5 g as a single daily dose for 2-3 days. Alternatively, 1.5-2.5 g as a single dose for 2-3 days.
Child: 1-3 years: ¼ adult dose; 3-7 years: 1/3 adult dose; 7-10 years: ½ adult dose. Alternatively, 35-50 mg/kg daily in divided doses.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Balantidiasis
Adult: 400-800 mg tid for 5-10 days or 1.5-2.5 g as a single daily dose for 2-3 days. Alternatively, 1.5-2.5 g as a single dose for 2-3 days.
Child: 1-3 years: ¼ adult dose; 3-7 years: 1/3 adult dose; 7-10 years: ½ adult dose. Alternatively, 35-50 mg/kg daily in divided doses.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Blastocystis hominis infection
Adult: 400-800 mg tid for 5-10 days or 1.5-2.5 g as a single daily dose for 2-3 days. Alternatively, 1.5-2.5 g as a single dose for 2-3 days.
Child: 1-3 years: ¼ adult dose; 3-7 years: 1/3 adult dose; 7-10 years: ½ adult dose. Alternatively, 35-50 mg/kg daily in divided doses.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral
Trichomoniasis
Adult: 2 g as a single dose, or 800 mg in the morning and 1.2 g in the evening for 2 days, or 0.6-1 g daily in 2-3 divided doses for 7 days. There should be an interval of 4-6 weeks if treatment needs to be repeated.
Child: 1-3 years: 50 mg tid; 3-7 years: 100 mg bid; 7-10 years: 100 mg tid. All doses to be taken for 7 days. Alternatively, 15 mg/kg daily in divided doses for 7 days.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral
Giardiasis
Adult: 2 g once daily for 3 consecutive days, or 400 mg tid for 5 days, or 500 mg bid for 7-10 days.
Child: 1-3 years: ¼ adult dose; 3-7 years: 1/3 adult dose; 7-10 years: ½ adult dose. Alternatively, 15 mg/kg daily in divided doses.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Bacterial vaginosis
Adult: 2 g as a single dose, or 400-500 mg bid for 5-7 days.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)             Dosage Recommendation
<10                           Consider reducing dose during long-term therapy.
Hepatic impairment:    Severe: 1/3 of usual dose given once daily.

Oral
Acute necrotising ulcerative gingivitis
Adult: 200 mg tid for 3 days.
Elderly: Dose reductions may be required.


CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral
Acute dental infections
Adult: 200 mg tid for 3 days.
Elderly: Dose reductions may be required.


CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral
Anaerobic bacterial infections
Adult: Initially, 800 mg followed by 400 mg 8 houly for about 7 days. Other recommended doses: 500 mg 8 hourly or 7.5 mg/kg 6 hourly (max: 4 g in 24 hours).
Child: 7.5 mg/kg 8 hourly.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.


CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Prophylaxis of postoperative anaerobic bacterial infections
Adult: 400 mg by mouth 8 hourly in the 24 hour prior to surgery followed postoperatively by IV or rectal admin until oral therapy is possible. Other sources recommend that oral doses be initiated only 2 hours prior to surgery and that number of doses for all admin routes be limited to a total of 4.
Elderly: Dose reduction may be necessary.

CrCl (ml/min)               Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Eradication of H. pylori associated with peptic ulcer disease
Adult: In combination with another antibacterial (e.g. clarithromycin) plus either a proton pump inhibitor (e.g. lansoprazole) or ranitidine bismuth citrate: 400 mg bid. In combination with omeprazole and amoxicillin: 400 mg tid. Continue treatment for 1 week.
Elderly: Dose reduction may be necessary.

CrCl (ml/min)               Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Leg ulcers and pressure sores
Adult: 400 mg tid for 7 days.
Elderly: Dose reduction may be necessary.


CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Oral

Antibiotic-associated colitis
Adult: 250-500 mg bid-tid for 10-14 days. Transfer to oral vancomycin is recommended if there is no clear clinical response after 2 days of treatment.
Child: 20 mg/kg/day 6 hourly. Max dose: 2 g/day. Transfer to oral vancomycin is recommended if there is no clear clinical response after 2 days of treatment.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Intravenous
Anaerobic bacterial infections
Adult: 500 mg infused as 100 ml of a 5 mg/ml solution at 5 ml/min 8 hourly. Alternatively, 15 mg/kg infusion followed by 7.5 mg/kg 6 hourly; infuse over 1 hour (max: 4 g in 24 hours). Substitute oral therapy as soon as possible.
Child: 7.5 mg/kg 8 hourly.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)              Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Intravenous
Prophylaxis of postoperative anaerobic bacterial infections
Adult: 500 mg by IV infusion shortly before operation and repeated 8 hourly; oral doses of 200 or 400 mg 8 hourly being substituted as soon as possible. Patient undergoing colorectal surgery: 15 mg/kg infused over 30-60 minutes, completed about 1 hour prior to surgery, followed by 2 further IV doses of 7.5 mg/kg infused at 6 and 12 hours after the initial dose.
Elderly: Use lower end of adult dose recommendations. Do not admin as a single dose.

CrCl (ml/min)               Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Rectal
Anaerobic infections
Adult: As a 1-g suppository 8 hourly for 3 days, then 12 hourly. Substitute oral therapy as soon as possible. May be unsuitable for initiating therapy in severe infections.
Child: <1 year: 125 mg; 1-5 years: 250 mg; 5-10 years: 500 mg. All doses to be given 8 hourly for 3 days, then 12 hourly thereafter. May be unsuitable for initiating therapy in severe infections.
Elderly: Dose reduction may be necessary.

CrCl (ml/min)               Dosage Recommendation
<10                            Consider reducing dose during long-term therapy.
Hepatic impairment:     Severe: 1/3 of usual dose given once daily.

Rectal

Prophylaxis of postoperative anaerobic bacterial infections
Adult: 1 g 8 hourly starting 2 hours before surgery.
Elderly: Dose reduction may be necessary.

CrCl (ml/min)    Dosage Recommendation
<10                  Consider reducing dose during long-term therapy.

Topical/Cutaneous
Bacterial vaginosis
Adult: Apply 5 g of a 0.75% gel once or bid for 5 days.

Topical/Cutaneous
Fungating tumours
Adult: Apply as a 0.75 or 0.8% gel to the affected area.

Topical/Cutaneous
Rosacea
Adult: Apply and rub a thin film once daily (1% formulation) or bid (0.75% formulation) to entire affected areas after washing. Significant response should be noticed within 3 weeks. Clinical studies have demonstrated continuing improvement through 9 wk of therapy.

Reconstitution

Reconstitute powder for injection by adding 4.4 ml of sterile or bacteriostatic water for injection, 0.9% sodium chloride injection or bacteriostatic sodium chloride injection to a vial labeled as containing 500 mg metronidazole. Reconstituted solution contains approx 100 mg/ml metronidazole and must be further diluted with 0.9% sodium chloride inj, 5% dextrose inj or lactated Ringer's injection to a concentration of ≤ 8 mg/ml metronidazole. Neutralise reconstituted and diluted metronidazole hydrochloride solution by adding approx 5 mEq of sodium bicarbonate injection for each 500 mg metronidazole.

Incompatibility

Incompatible with aztreonam, dopamine, meropenem.

Food(before/after)

Tab: Should be taken with food.
Susp: Should be taken on an empty stomach. (Take at least 1 hr before meals.)

List of Contraindications

Metronidazole and Pregnancy

Contraindicated in pregnancy

Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Metronidazole and Lactation

Contraindicated in lactation

Metronidazole and Children

Safety and efficacy not established, except for amebiasis

Metronidazole and Geriatic

Monitoring serum levels may be necessary for proper dosing

Metronidazole and Other Contraindications

History of hypersensitivity to metronidazole or other nitroimidazole derivatives. Pregnancy (1st trimester) and lactation.

Storage

Intravenous
Store at 15-30°C and protect from light

Lab interference

Intravenous
Store at 15-30°C and protect from light

© 2011-2023 DrugsUpdate.com. Disclaimer | Site Map

Feedback
  • Companies that own platforms will own the market
  • Trusted and recognized by all Doctors
  • Access to Millions of Visitors instantly.
  • Companies that own platforms will own the market
  • Trusted and recognized by all Doctors
  • Access to Millions of Visitors instantly.