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.
Excreted in human milk; not recommended
Indication
Pneumonia, Giardiasis, Peptic ulcer disease, Peritonitis, H. pylori infection, Rosacea, Septicemia, Endometritis, Aspiration pneumonia, Lung abscess, Empyema, Bone and Joint Infections, Surgical Prophylaxis, Amoebiasis, Bacterial vaginosis, Balantidiasis, Blastocystis hominis infection, Trichomoniasis, Acute dental infections, Acute necrotising ulcerative gingivitis, Anaerobic bacterial infections, Antibiotic-associated colitis, Fungating tumours, Leg ulcers and pressure sores, Diverticulitis, Diabetic foot ulcer, Meningitis and brain abscesses, endocarditis
Contra Indication
History of hypersensitivity to metronidazole or other nitroimidazole derivatives. Pregnancy (1st trimester) and lactation.
Dose
N/A
Side Effect
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.
Pregnancy Category
Name :
A
Description
Adequate and well-controlled human studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters).
Mode of Action
Metronidazole is converted to reduction products that interact w/ DNA to cause destruction of helical DNA structure and strand leading to a protein synthesis inhibition and cell death in susceptible organisms. It is active against most anaerobic protozoa, some gm+ve, gm-ve and facultative anaerobes.
Interaction
Concurrent use w/ disulfiram may produce psychotic reactions. May potentiate the effect of oral anticoagulants. May increase risk of lithium toxicity. May reduce the renal clearance resulting to increased toxicity of 5-fluorouracil. May increase serum levels of ciclosporin. May increase plasma levels of busulfan resulting to severe busulfan toxicity. Enhanced metabolism w/ phenobarbital and phenytoin resulting to decreased serum concentrations.
Pregnancy Category Note
Pregnancy
There are no adequate and well-controlled studies of in pregnant women; there are published data from case-control studies, cohort studies, and 2 meta-analyses that include more than 5000 pregnant women who used metronidazole during pregnancy; many studies included first trimester exposures; one study showed increased risk of cleft lip, with or without cleft palate, in infants exposed to metronidazole in utero; however, these findings were not confirmed
Metronidazole crosses placental barrier and its effects on human fetal organogenesis are not known; reproduction studies have been performed in rats, rabbits and mice at doses similar to maximum recommended daily dose based on body surface area comparisons; there was no evidence of harm to fetus due to metronidazole; healthcare provider should carefully consider potential risks and benefits for each specific patient before prescribing therapy
Lactation
Metronidazole is present in human milk at concentrations similar to maternal serum levels, and infant serum levels can be close to or comparable to infant therapeutic levels
Because of potential for tumorigenicity shown for metronidazole in mouse and rat studies, a decision should be made whether to discontinue nursing or to discontinue drug, taking into account importance of drug to mother; alternatively, a nursing mother may choose to pump and discard human milk for duration of metronidazole therapy, and for 24 hours after therapy ends and feed her infant stored human milk or formula
Adult Dose
Oral
Child: PO 30?50 mg/kg/day q8h
Amoebiasis
Adult: 800 mg tid for 5 days (intestinal infection); 5-10 days (extra-intestinal infection). Max: 2.4 g/day.
Trichomoniasis
Adult: 2 g as a single dose, 200 mg tid for 7 days or 400 mg bid for 5-7 days. Sexual partners should also be treated. Repeat treatment 4-6 wk between courses as necessary.
Giardiasis
Adult: 2 g once daily for 3 days, 400 mg tid for 5 days or 500 mg bid for 7-10 days.
Bacterial vaginosis
Adult: 2 g as a single dose or 400 mg bid for 5-7 days.
Acute necrotising ulcerative gingivitis
Adult: 200 mg tid for 3 days.
Anaerobic bacterial infections
Adult: Initially, 800 mg followed by 400 mg 8 hrly. Alternatively, 7.5 mg/kg 6-8 hrly. Max: 4 g/day. Duration of treatment is usually for 7 days depending on the severity of infection.
Prophylaxis of postoperative anaerobic bacterial infections
Adult: 400 mg 8 hrly 24 hr prior to surgery followed by post-op IV or rectal admin until oral therapy is possible.
Eradication of H. pylori associated with peptic ulcer disease
Adult: 400 mg bid in combination w/ another antibacterial and a PPI or 400 mg tid, if given w/ omeprazole and amoxicillin. Initial treatment is given for 1 wk.
Leg ulcers and pressure sores
Adult: 400 mg tid for 7 days.
Acute dental infections
Adult: 200 mg tid for 3-7 days.
Intravenous
Children: IV 22.5?40 mg/kg/day q8h
Anaerobic bacterial infections
Adult: 500 mg infused as 100 mL of a 5 mg/mL soln at 5 mL/min 8 hrly. Alternatively, 15 mg/kg infused over 1 hr, followed by 7.5 mg/kg infused over 1 hr 6 hrly. Max: 4 g/day. Substitute oral therapy as soon as possible.
Prophylaxis of postoperative anaerobic bacterial infections
Adult: 500 mg shortly before operation and repeated 8 hrly. Alternatively, 15 mg/kg infused over 30-60 min and completed approx 1 hr before surgery, followed by 7.5 mg/kg infused over 30-60 min at 6 and 12 hr after the initial dose.
Hepatic impairment: Severe: 1/3 of usual dose once daily.
Child Dose
Oral
Amoebiasis
Child: 1-3 yr 100-200 mg tid;
>3-7 yr 100-200 mg 4 times daily;
>7-10 yr 200-400 mg tid. Doses are given for 5-10 days.
Trichomoniasis
Child: 1-10 yr 40 mg/kg as a single dose or 15-30 mg/kg daily in 2-3 divided doses for 7 days. Max: 2 g/dose.
Giardiasis
Child: 1-3 yr 500 mg once daily;
>3-7 yr 600-800 mg once daily;
>7-10 yr 1 g once daily. Doses are given for 3 days.
Acute necrotising ulcerative gingivitis
Child: 1-3 yr 50 mg tid;
>3-7 yr 100 mg bid;
>7-10 yr 100 mg tid. Doses are given for 3 days.
Anaerobic bacterial infections
Child: <8 wk 7.5 mg/kg 12 hrly or 15 mg/kg once daily.
8 wk to 12 yr 7.5 mg/kg 8 hrly or 20-30 mg/kg once daily. Duration of treatment is usually for 7 days depending on the severity of infection.
Prophylaxis of postoperative anaerobic bacterial infections
Child: <40 wk 10 mg/kg as a single dose before surgery;
<12 yr 20-30 mg/kg as a single dose 1-2 hr before surgery.
Intravenous
Anaerobic bacterial infections
Child: 7.5 mg/kg 8 hrly.
Renal Dose
N/A
Administration
Susp: Should be taken on an empty stomach. Take at least 1 hr before meals.
Tab: Should be taken with food.
Reconstitution: Add 4.4 mL of sterile or bacteriostatic water for inj, NaCl 0.9% inj, or bacteriostatic NaCl inj to a vial labeled as containing metronidazole 500 mg. The resultant soln contains approx 100 mg/mL and must be further diluted w/ NaCl 0.9% inj, dextrose 5% inj, or lactated Ringer's inj to a concentration of 8 mg/mL or less. The reconstituted and diluted soln must then be neutralised by adding approx 5 mEq of Na bicarbonate inj for each 500 mg.
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