Metronidazole
Mechanism :
Metronidazole is a nitroimidazole anti-infective drug used mainly in the treatment of infections caused by susceptible organisms, particularly anaerobic bacteria and protozoa. The nitro group of metronidazole is chemically reduced by ferredoxin and the products are responsible for disrupting the DNA helical structure, thus inhibiting nucleic acid synthesis.
Indication :
- Amoebiasis
- Giardiasis
- Trichomoniasis
- Balantidium coli infection
- Helicobacter pylori infections
- Duodenal ulcer
- Propionic acidemia
- Methylmalonic acidemia
Contraindications :
Contraindicated in patients with a prior history of hypersensitivity to metronidazole or other nitroimidazole derivatives and during the first trimester of pregnancy. Use with caution and reduce dose in severe hepatic impairment.
Dosing :
Newborn:
<1.2 kg: 7.5 mg/kg IV/PO every 2 days.
<7 days, 1.2-2 kg: 7.5 mg/kg IV/PO every day.
<7 days, >2 kg or >7 days, 1.2-2 kg: 15 mg/kg/day IV/PO in 2 divided doses.
>7 days, >2 kg: 30 mg/kg/day IV/PO in 2 divided doses.
Infants and children:
30 mg/kg/day IV/PO in 4 divided doses. Max: 4 g/day.
Clostridium difficile colitis:
30 mg/kg/day IV/PO in 4 divided doses for 7-10 days.
Amoebiasis:
35-50 mg/kg PO in 3 divided doses for 10 days.
Giardiasis:
15 mg/kg/day IV/PO in 3 divided doses for 5 days.
Trichomoniasis:
15 mg/kg/day IV/PO in 3 divided doses for 7 days. Max: 2 g/day.
Helicobacter pylori
associated peptic ulcer disease with
amoxicillin and bismuth subsalicylate: 15-20 mg/kg/day orally, in 2 divided doses for 2 weeks.
Adverse Effect :
Nausea, vomiting, unpleasant taste, diarrhea, loss of appetite, darkening of urine, drowsiness, dizziness, headache and ataxia, skin rashes, xerostomia, furry tongue, pancreatitis, urticaria, myalgia and arthralgia. During intensive or prolonged therapy, seizures or peripheral neuropathy have occurred. Mild leukopenia, thrombocytopenia, aseptic meningitis, Stevens-Johnson syndrome, toxic epidermal necrolysis, optic neuropathy may occur rarely.
Interaction :
Warfarin: Potentiates anticoagulant effects.
Lithium: Increased levels of lithium may lead to lithium toxicity.
Phenytoin: Increased levels may occur, and levels should be monitored.
Cimetidine: Reduces hepatic metabolism of metronidazole leading to increased serum levels and potentially increased incidence of side-effects.
Phenobarbital: May significantly decrease serum levels.
Alcohol: Disulfiram reaction may occur with alcohol and the alcohol content of concurrently administered medication should be considered.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in normal renal function |
| HD | Dialysed. Dose as in normal renal function |
| HDF/High flux | Dialysed. Dose as in normal renal function |
| CAV/VVHD | Unknown dialysability. Dose as in normal renal function |
Hepatic Dose :
Topical Application: No dose adjustment is recommended.
Systemic use: Reduce the dose by 50% in patients with severe hepatic impairment