Metronidazole oral
- Drugs List
- Therapeutic Indications
- Dosage
- Contraindications
- Precautions and Warnings
- Pregnancy and Lactation
- Side Effects
- Monograph
Presentation
Oral formulations containing metronidazole.
Drugs List
Therapeutic Indications
Uses
Amoebiasis - intestinal,extra-intestinal, and for symptomless cyst passers
Dental infections - acute
Eradication of Helicobacter pylori (with other drugs)
Fistulating Crohn's disease
Giardiasis
Gingivitis - acute ulcerative
Leg ulcer - infected with anaerobes
Pelvic inflammatory disease
Post operative anaerobic bacterial infection - prophylaxis
Pressure sores - infected with anaerobes
Susceptible anaerobic infection(s)
Urogenital trichomoniasis
Vaginosis - bacterial
Metronidazole is active against a range of pathogenic micro-organisms notably species of Bacteroides, Fusobacteria, Clostridia, Entamoeba histolytica, Balantidium coli, Trichomonas, Giardia lamblia, Eubacteria, anaerobic cocci, Gardnerella vaginalis and Helicobacter pylori .
Dosage
Adults
Prophylaxis of postoperative infections
Various schedules are recommended including (but not limited to):
400mg every 8 hours starting 24 hours before surgery. Postoperatively, continue treatment intravenously or rectally until able to restart oral medication.
Alternatively an initial dose of 1g as a single dose 24 hours before surgery, followed by 200mg to 400mg every 8 hours. Postoperatively, continue treatment by intravenous or rectal administration until patient is able to take oral medication.
Alternative sources also recommend the following dose:
400mg to 500mg administered 2 hours before surgery, then 400mg to 500mg every 8 hours if required for up to 3 doses (in high risk procedures).
Treatment of established anaerobic infection
400mg every 8 hours. Some manufacturers suggest a loading dose of 800mg. Treatment is usually for 7 days.
Alternative sources also recommend the following dose:
500mg every 8 hours usually treated for 7 days. Treat for 10-14 days in Clostridium difficile infection.
Treatment of urogenital trichomoniasis
Either 200mg three times daily for 7 days or 400mg twice daily for 5 to 7 days or 2g as a single dose.
Sexual partners should receive similar concurrent treatment.
Bacterial vaginosis
Either 400mg twice daily for 5 to 7 days or 2g as a single dose.
Amoebiasis
Invasive intestinal disease in susceptible subjects:
800mg three times daily for 5 days.
Intestinal disease in less susceptible subjects and chronic amoebic hepatitis:
400mg three times daily for 5 to 10 days.
Amoebic liver abscess, also other forms of extra-intestinal amoebiasis:
400mg three times daily for 5 days.
Eradication of cysts in symptomless carriers:
400mg to 800mg three times daily for 5 to 10 days.
Giardiasis
2g once daily for 3 days or 400mg three times daily for 5 days or 500mg twice daily for 7 to 10 days.
Acute ulcerative gingivitis
200mg three times daily for 3 days.
Alternative sources also recommend the following dose:
400mg every 8 hours for 3 days.
Acute dental infections
200mg three times daily for 3 to 7 days.
Alternative sources also recommend the following dose:
400mg every 8 hours for 3-7 days.
Leg ulcers and pressure sores
400mg three times daily for 7 days.
Combination treatment for Helicobacter pylori eradication
Used as part of a combination therapy, dose and treatment is dependant on concomitant medication.
400mg three times a day or 400mg twice a day.
Alternative sources recommend the following doses for these additional indications:
Pelvic inflammatory disease
400mg twice daily for 14 days.
Fistulating Crohn's disease
10mg/kg to 20mg/kg daily in divided doses, usual dose 400mg to 500mg three times a day, usually given for 1 month but should not be used for longer than 3 months.
Children
Prophylaxis of postoperative infections
Children 12 to 18 years:(See Dosage; Adult)
Children under 12 years:20mg/kg to 30mg/kg (maximum 500 mg) as a single dose given 1 to 2 hours before surgery.
Treatment of established anaerobic infection
Children 12 to 18 years:(See Dosage; Adult)
Children 8 weeks to 12 years:20mg/kg to 30mg/kg once daily or 7.5mg/kg every 8 hours. The dose may be increased to 40mg/kg daily, depending on the severity of the infection. Treatment is usually for 7 days.
Children under 8 weeks: 15mg/kg once daily or 7.5mg/kg every 12 hours.
Treatment of urogenital trichomoniasis
Children 10 to 18 years: (See Dosage; Adult)
Children 1 to 10 years: 40mg/kg given as a single dose or 15mg/kg to 30mg/kg per day divided in 2 or 3 doses given for 7 days. Do not exceed 2g per dose.
Alternative sources also recommend the following dose:
Children 7 to 10 years:100mg three times a day for 7 days.
Children 3 to 7 years:100mg twice daily for 7 days.
Children 1 to 3 years: 50mg three times a day for 7 days.
Bacterial vaginosis
Children 10 to 18 years:(See Dosage; Adult)
Amoebiasis
Invasive intestinal disease in susceptible subjects:
Children 10 to 18 years: (See Dosage; Adult)
Children 7 to 10 years: 400mg three times daily for 5 days.
Children 3 to 7 years: 200mg four times daily for 5 days.
Children 1 to 3 years: 200mg three times daily for 5 days.
Intestinal disease in less susceptible subjects and chronic amoebic hepatitis:
Children 10 to 18 years: (See Dosage; Adult)
Children 7 to 10 years:200mg three times daily for 5 to 10 days.
Children 3 to 7 years:100mg four times daily for 5 to 10 days.
Children 1 to 3 years:100mg three times daily for 5 to 10 days.
Amoebic liver abscess, also other forms of extra-intestinal amoebiasis:
Children 10 to 18 years:(See Dosage; Adult)
Children 7 to 10 years:200mg three times daily for 5 days.
Children 3 to 7 years:100mg four times daily for 5 days.
Children 1 to 3 years:100mg three times daily for 5 days.
Eradication of cysts in symptomless carriers:
Children 10 to 18 years:(See Dosage; Adult)
Children 7 to 10 years:200mg to 400mg three times daily for 5 to 10 days.
Children 3 to 7 years:100mg to 200mg four times daily for 5 to 10 days.
Children 1 to 3 years:100mg to 200mg three times daily for 5 to 10 days.
Giardiasis
Children 10 to 18 years: (See Dosage; Adult)
Children 7 to 10 years: 1g once daily for 3 days.
Children 3 to 7 years:600mg to 800mg once daily for 3 days.
Children 1 to 3 years:500mg once daily for 3 days.
Acute ulcerative gingivitis
Children 10 to 18 years:(See Dosage; Adult)
Children 7 to 10 years:100mg three times daily for 3 days.
Children 3 to 7 years:100mg twice daily for 3 days.
Children 1 to 3 years: 50mg three times daily for 3 days.
Acute dental infections
Children 10 to 18 years:(See Dosage; Adult)
Alternative sources also recommend the following dose:
Children 10 to 18 years: 200mg-250mg every 8 hours for 3-7 days.
Children 7 to 10 years: 100mg every 8 hours for 3-7 days.
Children 3 to 7 years: 100mg every 12 hours for 3-7 days.
Children 1 to 3 years: 50mg every 8 hours for 3-7 days.
Leg ulcers and pressure sores
Children 10 to 18 years:(See Dosage; Adult)
Combination treatment for Helicobacter pylori eradication
Used as part of a combination therapy, dose and treatment is dependant on concomitant medication.
20mg/kg per day (maximum 500mg twice daily), for 7 to 14 days.
Alternative sources also recommend the following dose:
Children 12 to 18 years: 400mg three times a day or 400mg twice a day.
Children 6 to 12 years: 200mg three times a day or 200mg twice a day.
Children 1 to 6 years: 100mg three times a day or 100mg twice a day.
Alternative sources recommend the following doses for these additional indications:
Pelvic inflammatory disease
Children 12 to 18 years: 400mg twice daily for 14 days.
Fistulating Crohn's disease
Under 18 years: 7.5mg/kg three times a day, usually given for 1 month but should not be used for longer than 3 months.
Neonates
Treatment of established anaerobic infection
15mg/kg once daily or 7.5mg/kg every 12 hours.
The manufacturers advise monitoring serum metronidazole levels in newborns with a gestational age less than 40 weeks.
Prophylaxis of postoperative infections
Neonates with a gestational age of 40 weeks or more: 20mg/kg to 30mg/kg as a single dose given 1 to 2 hours before surgery.
Neonates with a gestational age less than 40 weeks: 10mg/kg as a single dose before operation.
Patients with Renal Impairment
Metronidazole should be re-administered immediately after haemodialysis since metronidazole and its metabolites are efficiently removed during an eight hour period of dialysis.
In patients undergoing intermittent peritoneal dialysis or continuous ambulatory peritoneal dialysis (CAPD) no routine dosage adjustment is required.
Patients with Hepatic Impairment
The dosage of metronidazole should be reduced to one third of the recommended daily dose, administered once daily in patients with hepatic encephalopathy.
Contraindications
None known
Precautions and Warnings
Elderly
Breastfeeding
Cockayne syndrome
Epileptic disorder
Galactosaemia
Glucose-galactose malabsorption syndrome
Haematological disorder
Haemodialysis
Hepatic encephalopathy
Hepatic impairment
Hereditary fructose intolerance
History of haematological disorder
History of seizures
Lactose intolerance
Pregnancy
Severe neurological disorder
High doses may mask syphilis
Advise ability to drive/operate machinery may be affected by side effects
Not all presentations are licensed for all indications
Presentations with sorbitol unsuitable in hereditary fructose intolerance
Some formulations contain glucose
Some formulations contain lactose
Some formulations contain sucrose
Consider AGEP if feverish generalised erythema occurs
If rash develops, consider possibility of Stevens-Johnson Syndrome
Monitor for signs of bone marrow depression
Monitor for symptoms of peripheral neuropathy
Regular clinical and lab. tests recommended for treatment of > 10 days
Discontinue treatment if Stevens-Johnson Syndrome suspected
Discontinue treatment if toxic epidermal necrolysis is suspected
Discontinue permanently if AGEP is diagnosed
Avoid prolonged use
Advise patient not to take alcohol during and for 48 hours after therapy
Advise patient that alcohol ingestion may cause a disulfiram-like reaction
In patients with Cockayne syndrome monitor liver function tests before initiating therapy, throughout treatment and at the end of treatment until results are within normal ranges or return to baseline. Treatment should be discontinued if liver function tests become elevated. Advise patients to report any symptoms of potential liver disorder or liver injury.
If metronidazole is administered for more than 10 days, regular clinical and laboratory monitoring is advised. Patients should also be monitored for adverse reactions such as peripheral and central neuropathy.
There is a possibility that after Trichomonas vaginalis has been eliminated a gonococcal infection might persist.
Caution is advised in patients with active or chronic severe neurological disorders as treatment may aggravate the condition.
Pregnancy and Lactation
Pregnancy
Use metronidazole with caution in pregnancy.
The risk of possible sequelae for the foetus, including carcinogenic risk later in life, is not yet clarified. However, there is no proven evidence of damage to the embryo or foetus being caused by metronidazole. The manufacturers advise avoiding treatment unless considered essential.
Short high dose regimens are not recommended.
When used to treat trichomoniasis or bacterial vaginosis, metronidazole is contraindicated in the first trimester and caution is advised in the second and third trimester.
The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).
Lactation
Use metronidazole with caution in breastfeeding.
Metronidazole is found in breast milk but levels of metronidazole and metabolite are lower than those used to treat infections in infants. Short high-dose regimens are not recommended. Some sources advise to stop breastfeeding until 12-24 hours after metronidazole therapy has been discontinued. Manufacturers advise avoiding treatment unless it is considered essential.
Candidal infections and diarrhoea have been reported in exposed infants. Milk may take on a bitter taste.
Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1
Side Effects
Acute generalised exanthematous pustulosis
Agranulocytosis
Anaphylaxis
Angioedema
Anorexia
Aplastic anaemia
Arthralgia
Aseptic meningitis
Ataxia
Bone marrow depression
Cholestatic hepatitis
Confusion
Convulsions
Darkening of urine
Depression
Diarrhoea
Diplopia
Disulfiram-alcohol reactions on ingestion of alcohol
Dizziness
Drowsiness
Dysarthria
Elevation of liver enzymes
Encephalopathy
Epigastric pain
Epileptiform seizures
Erythema multiforme
Fever
Fixed drug eruption
Flushing
Furred tongue
Gait abnormality
Gastro-intestinal disturbances
Hallucinations
Headache
Hearing disturbances
Hearing loss
Hepatotoxicity
Hypersensitivity reactions
Jaundice
Leucopenia
Mucositis
Myalgia
Myopia
Nausea
Neutropenia
Nystagmus
Optic neuritis
Optic neuropathy
Pancreatitis
Pancytopenia
Paraesthesia
Paralysis
Peripheral neuropathy
Pruritus
Psychotic reactions
Pustular rash
Rash
Stevens-Johnson syndrome
Subacute cerebellar syndrome
Thrombocytopenia
Tinnitus
Toxic epidermal necrolysis
Tremor
Unpleasant taste
Urticaria
Visual disturbances
Vomiting
Overdosage
It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.
The following number will direct the caller to the relevant local centre (0844) 892 0111
Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).
Further Information
Last Full Review Date: May 2018
Reference Sources
Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.
Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.
Summary of Product Characteristics: Flagyl 200mg tablets. Zenvita. Revised January 2017.
Summary of Product Characteristics: Flagyl 400mg tablets. Zenvita. Revised January 2017.
Summary of Product Characteristics: Flagyl 200mg tablets. Sanofi. Revised September 2018.
Summary of Product Characteristics: Flagyl 400mg tablets. Sanofi. Revised September 2018.
Summary of Product Characteristics: Metronidazole tablets 200mg. Actavis UK Ltd. Revised March 2012.
Summary of Product Characteristics: Metronidazole tablets 400mg. Actavis UK Ltd. Revised March 2012.
Summary of Product Characteristics: Metronidazole tablets 500mg. Actavis UK Ltd. Revised July 2017.
Summary of Product Characteristics: Metronidazole 200mg/5ml Oral Suspension. Rosemont Pharmaceuticals Limited. Revised May 2017.
Summary of Product Characteristics: Metronidazole tablets 200mg. Sandoz Ltd. Revised January 2017.
Summary of Product Characteristics: Metronidazole tablets 400mg. Sandoz Ltd. Revised January 2017.
US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
Available at: https://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT
Metronidazole. Last revised: February 04, 2016
Last accessed: February 02, 2018
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