Metronidazole - oral


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Anaerobic bacterial infections Initial: 800 mg followed by 400 mg 8 hourly usually for about 7 days. Max: 4,000 mg/day. Prophylaxis of postoperative anaerobic bacterial infections 400 mg 8 hourly in the 24 hours before surgery followed by IV or rectal dosage post-operatively until oral therapy is possible. Max: 4,000 mg/day. Amoebiasis 800 mg tid 5 days (intestinal infection); 400-800 mg for 5-10 days (extra-intestinal infection). Alternatively, 35-50 mg /kg daily in 3 divided doses for 5-10 days. Max: 2,400 mg/day Trichomoniasis 2,000 mg as a single dose or 200 mg tid for 7 days. Alternatively, 400 mg bid for 5-7 days. Sexual partners should also be treated. Bacterial vaginosis 400 mg bid for 5-7 days. Alternatively, 2,000 mg as single dose. Giardiasis 2,000 mg once daily for 3 days or 400 mg tid for 5 days or 500 mg bid for 7-10 days. Alternatively, 15-40 mg/kg/day in 2-3 divided doses. H. pylori eradication associated with peptic ulcer disease Combined with another antibacterial and PPI: 400 mg bid for 7-14 days. Combined with omeprazole and amoxicillin: 400 mg tid. Consult official guidelines before initiating therapy. Acute ulcerative gingivitis 200-400 mg tid for 3 days. Acute dental infections 200 mg tid for 3-7 days. Leg ulcers and pressure sores 400 mg tid for 7 days. IV Anaerobic bacterial infections 1,000-1,500 mg once daily as single dose. Alternatively, 500 mg 8 hourly via infusion at a rate of 5 mL/min over 20-60 minutes usually for about 7 days. Max: 4,000 mg/day. Substitute oral therapy as soon as possible Prophylaxis of post-op anaerobic bacterial infections 1,000-1,500 mg once daily for 30-60 minutes preoperatively. Alternatively, 500 mg immediately prior, during or after operation, then 500 mg 8 hourly for 24 hours. Rectal Anaerobic infections As supp: 1 g 8 hourly for 3 days, then reduce to 12 hourly if needs to continue for more than 3 days. Substitute oral therapy as soon as possible. Prophylaxis of post-op anaerobic bacterial infections As supp: 1 g 2 hours before surgery, repeated 8 hourly for 3 days, then 12 hourly until oral doses can be given to complete the 7-day treatment course. Intravaginal Bacterial vaginosis Each applicator delivers approx 5 gm gel containing 37.5 mg metronidazole: 1 applicator-full once daily at bedtime for 5 days. Topical/Cutaneous Rosacea As 0.75% gel/cream/lotion: Apply thinly to the affected area twice daily. Average treatment period: 3-4 months, may be continued for further 3-4 months may be necessary depending on the severity of the infection.
Dosage Details
Intravenous
Prophylaxis of postoperative anaerobic bacterial infections
Adult: 1,000-1,500 mg once daily for 30-60 minutes preoperatively. Alternatively, 500 mg immediately prior, during or after operation, then 500 mg 8 hourly for 24 hours.
Child: <12 years 20-30 mg/kg as single dose given 1-2 hours prior surgery.

Intravenous
Anaerobic bacterial infections
Adult: 1,000-1,500 mg once daily as single dose. Alternatively, 500 mg 8 hourly via infusion at a rate of 5 mL/min over 20-60 minutes usually for about 7 days. Max: 4,000 mg daily. Substitute oral therapy as soon as possible.
Child: 8 weeks 15 mg/kg once daily or divided into 7.5 mg/kg 12 hourly. >8 weeks to 12 years 20-30 mg/kg as a single dose or divided into 7.5 mg/kg 8 hourly. Treatment duration: Usually, 7 days. Daily dose may be increased to 40 mg/kg based on the severity of the infection.

Oral
Acute dental infections
Adult: 200 mg tid for 3-7 days.

Oral
Eradication of H. pylori associated with peptic ulcer disease
Adult: In combination with another antibacterial and PPI: 400 mg bid for 7-14 days. In combination with omeprazole and amoxicillin: 400 mg tid. Consult official guidelines before initiating therapy.
Child: In combination with another antibacterial and PPI: 20 mg/kg daily in divided doses for 7-14 days. Max 500 mg bid.

Oral
Trichomoniasis
Adult: 2,000 mg as a single dose or 200 mg tid for 7 days. Alternatively, 400 mg bid for 5-7 days. Sexual partners should also be treated.
Child: 40 mg/kg as single dose or 15-30 mg/kg daily in 2-3 divided doses. Max: 2,000 mg/dose.

Oral
Prophylaxis of postoperative anaerobic bacterial infections
Adult: 400 mg 8 hourly in the 24 hours before surgery followed by IV or rectal dosage post-operatively until oral therapy is possible. Max: 4,000 mg daily.
Child: Newborn <40 weeks 10 mg/kg as single dose before surgery. <12 years 20-30 mg/kg as a single dose given 1-2 hours before surgery.

Oral
Leg ulcers and pressure sores
Adult: 400 mg tid for 7 days.

Oral
Giardiasis
Adult: 2,000 mg once daily for 3 days or 400 mg tid for 5 days or 500 mg bid for 7-10 days. Alternatively, 15-40 mg/kg daily in 2-3 divided doses.
Child: 1-3 years 50 mg once daily for 3 days. >3-7 years 600-800 mg once daily for 3 days; >7-10 years 1,000 mg once daily for 3 days. >10 years Same as adult dose. Alternatively, 15-40 mg/kg daily in 2-3 divided doses.

Oral
Amoebiasis
Adult: 800 mg tid 5 days (intestinal infection); 400-800 mg for 5-10 days (extra-intestinal infection). Alternatively, 35-50 mg /kg daily in 3 divided doses for 5-10 days. Max: 2,400 mg daily.
Child: 1-3 years 200 mg tid for 5 days (intestinal); 100-200 mg tid for 5-10 days. 3-7 years 200 mg 4 times daily for 5 days (extra-intestinal); 100-200 mg 4 times daily for 5-10 days. 7-10 years 400 mg tid for 5 days (extra-intestinal); 400-800 tid for 5-10 days. Alternatively, 35-50 mg/kg daily in 3 divided doses for 5-10 days. Max: 2,400 mg daily.

Oral
Acute ulcerative gingivitis
Adult: 200 mg tid for 3 days.
Child: 1-3 years 50 mg tid for 3 days. >3-7 years 100 mg bid for 3 days; >7-10 years 100 mg tid for 3 days. >10 years Same as adult dose.

Oral
Anaerobic bacterial infections
Adult: Initially, 800 mg followed by 400 mg 8 hourly usually for about 7 days.
Child: <8 weeks 15 mg/kg once daily or divided into 7.5 mg/kg 12 hourly. >8 weeks to 12 years 20-30 mg/kg as a single dose or divided into 7.5 mg/kg 8 hourly for 7 days. The daily dose may be increased to 40 mg/kg based on the severity of the infection.

Oral
Bacterial vaginosis
Adult: 400 mg bid for 5-7 days. Alternatively, 2,000 mg as single dose.

Rectal
Anaerobic infections
Adult: As supp: 1 g 8 hourly for 3 days, then reduce to 12 hourly if needs to continue for more than 3 days. Substitute oral therapy as soon as possible.
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 until oral medication is possible. >10 years Same as adult dose.

Rectal
Prophylaxis of postoperative anaerobic bacterial infections
Adult: As supp: 1 g 2 hours before surgery, repeated 8 hourly until oral doses can be given to complete the 7-day treatment course.
Child: 5-10 years 500 mg supp 2 hours before surgery, repeated 8 hourly for 3 days, then 12 hourly until oral medication becomes possible. >10 years Same as adult dose.

Topical/Cutaneous
Rosacea
Adult: As 0.75% gel/cream/lotion: Apply thinly to the affected area twice daily. Average treatment period: 3-4 months, may be continued for further 3-4 months may be necessary depending on the severity of the infection.

Vaginal
Bacterial vaginosis
Adult: Each applicator delivers approx 5 gm gel containing 37.5 mg metronidazole: 1 applicator-full once daily at bedtime for 5 days.
Hepatic Impairment
Oral
Anaerobic bacterial infections; Prophylaxis of postoperative anaerobic bacterial infections; Bacterial vaginosis, Giardiasis;  H. pylori eradication associated with peptic ulcer disease; Acute ulcerative gingivitis; Acute dental infections; Leg ulcers and pressure sores:
Severe: Reduce dose by 50%.

Amoebiasis, Trichomoniasis:
Severe: 375 mg 8 hourly (cap); reduce dose by 50% (tab).

IV
Anaerobic bacterial infections; Prophylaxis of postoperative anaerobic bacterial infections:
Severe: Reduce dose by 50%.
Administration
Tab: Should be taken with food.
Susp: Should be taken on an empty stomach. Take at least 1 hr before meals.
Contraindications
Hypersensitivity to metronidazole and other nitroimidazoles. Concomitant use with disulfiram within the last 14 days. Coadministration with alcohol or propylene glycol containing products during or 3 days after therapy discontinuation. Pregnancy during the 1st trimester in the treatment of trichomoniasis.
Special Precautions
Patient with or history seizure disorder, blood dyscrasias (e.g. agranulocytosis, leukopenia, neutropenia); Cockayne syndrome. Hepatic impairment and severe renal impairment or ESRD. Pregnancy and lactation.
Adverse Reactions
Significant: Severe neurological disturbances, encephalopathy, convulsive seizures, aseptic meningitis, peripheral and optic neuropathy, paraesthesia; superinfection (e.g. fungal or bacterial superinfection, C. difficile-associated diarrhoea. Blood and lymphatic system disorders: Leucopenia, neutropenia.
Cardiac disorders: Chest pain, tachycardia.
Ear and labyrinth disorders: Tinnitus.
Eye disorders: Light sensitivity, nystagmus.
Gastrointestinal disorders: Nausea, dry mouth, vomiting, constipation, abdominal pain, diarrhoea, sharp unpleasant metallic taste.
Investigations: Flattening of T wave on ECG.
Metabolism and nutrition disorders: Anorexia.
Musculoskeletal and connective tissue disorders: Myalgia.
Nervous system disorders: Insomnia, headache, ataxia, vertigo, incoordination, dizziness.
Psychiatric disorders: Confusion, hallucination.
Reproductive system and breast disorders: Genital pruritus.
Respiratory, thoracic and mediastinal disorders: Pharyngitis, sinusitis.
Skin and subcutaneous tissue disorders: Erythematous rash, urticaria, dry skin.
Vascular disorders: Syncope.
Potentially Fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis; severe hepatotoxicity/acute hepatic failure in patients with Cockayne syndrome.
IV/Parenteral/PO/Topical/Vag: B
Patient Counseling Information
This drug may cause drowsiness, if affected do not drive or operate machinery.
MonitoringParameters
Monitor CBC with differential at baseline, during, and after repeated or prolonged treatment. Monitor LFT in patients with Cockayne syndrome. Monitor neurologic symptoms.
Overdosage
Symptoms: Nausea, vomiting, ataxia and slight disorientation. Management: Symptomatic and supportive treatment.
Drug Interactions
Confusional state or acute psychosis with disulfiram. May potentiate anticoagulant effect of warfarin. May retain lithium serum levels increasing the risk to renal damage. Decreased serum concentration with phenobarbital or phenytoin. May increase serum concentrations of ciclosporin and busulfan. May reduce the renal clearance of 5-fluorouracil.
Food Interaction
Disulfiram-like reaction characterized by confusion with alcoholic beverages. Food delays absorption (conventional tab/cap); increases the rate of absorption (extended-release tab).
Lab Interference
May interfere with AST, ALT, triglycerides, glucose hexokinase, and LDH testing.
Action
Description: Metronidazole interacts with the microbial DNA to break its strand and helical structure leading to inhibition of protein synthesis, degradation, and cell death.
Pharmacokinetics:
Absorption: Rapidly and almost completely absorbed from the gastrointestinal tract. Food delays absorption. Time to peak plasma concentration: 1-2 hours (oral); 20 minutes (IV); 5-12 hours (rectal); 8 hours (intravaginal gel). Bioavailability: 60-80% (rectal); 20-25% (vag pessaries); 56% (intravaginal gel).
Distribution: Widely distributed into most body tissues and fluids. Crosses blood-brain barrier. Readily crosses the placenta and enters breast milk in concentrations equal to the concurrent serum concentrations. Plasma protein binding: <20%.
Metabolism: Mainly metabolised in the liver via hydroxylation, side-oxidation, and glucuronidation to active hydroxyl metabolite and several metabolites.
Excretion: Via urine (60-80% as unchanged drug and metabolites; approx 20% of total as unchanged drug); faeces (6-15%). Elimination half-life: Approx 8 hours.
Chemical Structure

Chemical Structure Image
Metronidazole

Source: National Center for Biotechnology Information. PubChem Database. Metronidazole, CID=4173, https://pubchem.ncbi.nlm.nih.gov/compound/Metronidazole (accessed on Jan. 22, 2020)

Storage
Tab/topical cream/gel/lotion: Store between 15-25°C. Protect from light. IV: Store between 20-25°C. Protect from light. Do not refrigerate. Vaginal gel: Store between 15-30°C. Do not freeze. Protect from heat. Rectal supp: Store below 20°C. Protect from light.
ATC Classification
D06BX01 - metronidazole ; Belongs to the class of other topical chemotherapeutics used in the treatment of dermatological diseases.
G01AF01 - metronidazole ; Belongs to the class of imidazole derivative antiinfectives. Used in the treatment of gynecological infections.
P01AB01 - metronidazole ; Belongs to the class of nitroimidazole derivatives antiprotozoals. Used in the treatment amoebiasis and other protozoal diseases.
J01XD01 - metronidazole ; Belongs to the class of imidazole derivative antibacterials. Used in the systemic treatment of infections.
A01AB17 - metronidazole ; Belongs to the class of local antiinfective and antiseptic preparations. Used in the treatment of diseases of the mouth.
References
Anon. Metronidazole (Systemic). Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 11/02/2019.

Anon. Metronidazole (Sytemic). AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 11/02/2019.

Anon. Metronidazole (Topical). AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 12/02/2019.

Anon. Metronidazole (Topical). Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 08/07/2014.

Buckingham R (ed). Metronidazole. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/07/2014.

Flagyl 500 mg IV Inj RTU (in Plastic Container). U.S. FDA. https://www.fda.gov/. Accessed 08/07/2014.

Joint Formulary Committee. Metronidazole. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 11/02/2019.

McEvoy GK, Snow EK, Miller J et al (eds). Metronidazole, Metronidazole Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 08/07/2014.

MetroGel-Vaginal (Medicis Pharmaceutical Corp). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 12/02/2019.

Metrolyl 1 g Suppository (Sandoz Limited). MHRA. https://products.mhra.gov.uk/. Accessed 12/02/2019.

Metronidazole Capsule (Alembic Pharmaceuticals Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 11/02/2019.

Metronidazole Injection, Solution (Claris Lifesciences Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 08/07/2014.

Metronidazole Injection, Solution (Hospira Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 19/02/2019.

Metronidazole Lotion 0.75% (Prasco Laboratories). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 12/02/2019.

Metrosa 0.75% Gel (Dr. August Wolff GmbH & Co. KG Arzneimittel). MHRA. https://products.mhra.gov.uk/. Accessed 12/02/2019.

Vandazole (Upsher-Smith Laboratories, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 12/02/2019.

Disclaimer: This information is independently developed by MIMS based on Metronidazole from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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