Biotransformation reactions

Biotransformation reactions can lead to any one of the following:

• Inactivation – most drugs are rendered pharmacologically inactive
  • Example: Many drugs - morphine, chloramphenicol, procaine etc.
• Formation of active metabolite – the metabolite formed possesses biological activity
  • Ciprofloxacin from enrofloxacin
  • Oxyphenbutazone from Phenylbutazone
  • Salicylic acid from aspirin
• Inactive drug to active drug (Prodrug) An inactive drug gets converted into an active metabolite once it undergoes biotransfomation inside the body
  • Example:
    • Hetacillin to ampicillin 
    • Prontosil to sulfanilamide
• Less active or inactive drug is converted into a more toxic drug (Lethal synthesis)
  • Example:
    • Parathion to paraoxon
    • Fluoroacetic acid to fluorocitrate