METRONIDAZOLE

Structure/Class
  1. A nitro-imidazole anti-protozoan drug
Pharmacodynamics
  1. Metronidazole is taken up by anaerobes and then it is reduced to ferredoxin. This reduction will produce a toxic metabolite that kills anaerobes and protozoa.
  2. Spectrum of activity is against anaerobic bacteria (e.g. clostridium and bacteroides) and sensitive protozoa (amebiasis).
    • Therefore, indications as follows:
      1. Mixed intra-abdominal infections (in combination with other antibiotics)
      2. C.difficile colitis
      3. Bacterial vaginitis (where trichomonas is suspected – a single 2g dose may be enough)
      4. Amebiasis
      5. Giardiasis
      6. Brain abscess
Absorption/administration
  1. Well absorbed PO, but may be given IV or PR if necessary.
    • Low protein binding (10-20%)
Distribution
  1. Widely distributed, and does penetrate the CSF
Metabolism
  1. Hepatic – may accumulate in hepatic failure and dose reduction is required.
Excretion  
Adverse events
  1. It is an inhibitor of CYP450 enzymes and may increase the activity of warfarin.
  2. It has a disulfiram like effect and inhibits aldehyde dehydrogenase. Avoid taking with alcohol.
  3. Other reactions include nausea, diarrhea, stomatitis and peripheral neuropathy
Dosing/administration  
Toxicology  
Withdrawal syndrome  
Special notes