50. Therapeutic drug monitoring (TDM)

= measurement of drug concentration or activity in plasma

• Methods
  • High performance liquid chromatography
  • Immunoassay
• Indications
  • Non-linear kinetics of drug
  • When there is poor compliance
  • If the therapeutic effect can’t be assessed clinically
  • If the therapeutic index is low
    • Warfarin
    • Aminoglycosides
    • Antipsychotics
    • Digoxin
    • Lithium
  • When there are signs of overdose
  • To determine pharmacokinetic interactions