METRONIDAZOLE
ANTI-AMOEBIC DRUGS
- Tissue Amoebiasis
- Both intestinal & extraintestinal
- Nitroimidazoles – Metronidazole, Tinidazole, Secnidazole, Ornidazole
- Alkaloids – Emetine, Dehydroemetine
- Extraintestinal amoebiasis only – Chloroquine
- Both intestinal & extraintestinal
- Luminal amoebiasis
- Amide –Diloxanide furoate
- 8-Hydroxy quinolones –Quinidochlor
- Antibiotics – Tetracycline, Paromomycin
METRONIDAZOLE:
- Best drug against anaerobic infection.
- Bactericidal against,
- Giardia lamblia,
- Anaerobic bacteria – Bacteroides fragilis, Fusobacterium, Clostridium perfringes/difficile, Helicobacter pylori & Anaerobic Streptococci.
- Does not affect aerobic bacteria..
- Radiosensitising substance.
MOA
- Enters microorganism by diffusion.
- Nitro group reduced to highly reactive nitro radical – DNA damaged cytotoxicity.
- High selective anaerobic action – interference with electron transportation from NADPH or other reduced substrates.
- Also inhibits cell-mediated immunity.
- Induce mutagenesis.
- Cause radio-sensitization.
PHARMACOKINETICS:
- Completely absorbed from intestine.
- Wide distribution in body.
- t ½ – 8hrs.
- Therapeutic concentrations in – Vaginal secretions ,Semen ,Saliva, CSF.
- Route of administration – oral & parenteral.
ACTION:
- Broad spectrum cidal action for protozoa
- Anti-amoebiasis: Kills E histolytic trophozoites but not cysts.
- Treatment of all tissue infections with E histolytic.
- No effect against luminal parasites and so must be used with a luminal amoebicide to ensure eradication of the infection.
- Anti-trichomoniasis
- Bacterial vaginosis (creamy white vaginal discharge having fishy odour)
- Gardnerella vaginitis in pregnancy
- Anti-anaerobic bacteria
- Anti-giardiasis
- Pseudomembranous colitis:
- Presents with lower gastrointestinal bleed.
- Sigmoidoscopy shows ulcer in the sigmoid.
- Biopsy from this area shows flask-shaped ulcers.
- Ulcerative gingivitis,
- H.pylori, Peptic ulcer disease,(Clostridium difficile)
- Guinea worm infestation
- Brain Abscess: cephalosporin & metronidazole
ADVERSE EFFECT:
- Frequent –
- Anorexia, nausea, METALLIC TASTE, abdominal cramps, disulfiram reaction.
- Less frequent –
- Headache, glossitis, dry mouth, dizziness, rashes, transient neutropenia.
- On prolonged administration –
- Peripheral neuropathy, CNS effects.
Exam Important
- Drug of choice in bacterial vaginosis is Metronidazole.
- Treatment for Trichomonas vaginalis is Metronidazole.
- Treatment of choice in Gardenella vaginitis in pregnancy Metronidazole.
- A lady presented with a creamy white vaginal discharge having fishy odour,
- The clinical scenario is of bacterial vaginosis that can be treated with Metronidazole.
- Patient presenting with abdominal pain, diarrhea taking clindamycin for 5 days.
- Treated with metronidazole symptoms subsided.
- Causative micro-organism will be Clostridium difficile.
- A patient presents with lower gastrointestinal bleed.
- Sigmoidoscopy shows ulcer in the sigmoid. Biopsy from this area shows flask-shaped ulcers.
- Treatment will be Metronidazole
- Metronidazole causes flushing, vomiting, dizziness and rashes after taking alcohol.
- Best drug for anaerobic infections is Metronidazole.
- Metronidazole used in the treatment of Clostridium difficile associated diarrhoea.
- IV Metronidazole is used in the treatment of Pseudomembranous enterocolitis, Anaerobic bacterial infection & Amoebiasis.
- Metronidazole is a Radiosensitising substance.
- An elderly male presented with a headache, fever and hemiparesis of right side.
- On further examination and investigation a diagnosis of brain abscess was made.
- Treatment of choice is combination of cephalosporin and metronidazole.
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