•  Tissue Amoebiasis
  • Both intestinal & extra intestinal
  • Nitroimidazoles – Metronidazole , Tinidazole , Secnidazole , Ornidazole Alkaloids - Emetine , Hydroemetine
  • Extra intestinal amoebiasis only - Chloroquine
  • Luminal amoebiasis
  1. Amide –Diloxanide furoate
  2. 8-Hydroxy quinolones –Quinidochlor
  3. Antibiotics – Tetracycline,Paromomycin
  • Bactericidal against Giardia lamblia, anaerobic bacteria - Bacteroides fragilis, Fusobacterium, Clostridium perfringes/difficile, Helicobacter pylori, Anaerobic Streptococci. Does not affect aerobic bacteria.
  • Best drug against anaerobic infection
  • Metronidazole is a Radiosensitising substance
  • Not clearly understood
  1. Enters microorganism by diffusion - Nitro group reduced to a highly reactive nitro radical - DNA damaged Cytotoxicity.
  2. High selective anaerobic action – interference with electron transportation from NADPH or other reduced substrates
  • Also inhibits cell mediated immunity
  1. Induce mutagenesis
  2. Cause radio-sensitization
  • Completely absorbed from intestine
  •  Wide distribution in body.t ½ - 8hrs.
  • Therapeutic concentrations in -Vaginal secretions ,Semen ,Saliva, CSF 
  • Route of administration – oral & parenteral
  •  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
  1. Bacterial vaginosis(creamy white vaginal discharge having fishy odour)
  2. Gardenella vaginitis in pregnancy
  • Anti-anaerobic bacteria
  • Anti-giardiasis
  • Pseudomembranous colitis:
  1. Presents with lower gastrointestinal bleed.
  2. 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 and metronidazole
  • 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 Question
  • 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, diziness 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 elederly male presented with headache, fever and hemiparasis of right side. On further examination and investigation a diagnosis of brain abscess was made. Treatment of choice is combination of cephalosporin and metronidazole
Don't Forget to Solve all the previous Year Question asked on Metronidazole