Principles of pharmacology-the conc response curve

• How is the concentration-response relationship described?


  By studying the relationship between drug concentration (or dose) and the response produced by the drug
• What are the three main types of pharmacological experiments?


  • In vitro
  • In vivo
  • Ex vivo
• What does "in vitro" refer to in pharmacological experiments?


  Drug effects studied on a piece of tissue dissected from an animal and kept alive outside the body
• What is measured in in vivo experiments?


  Drug effects studied in the living animal or human
• What does "ex vivo" refer to in pharmacological experiments?


  A tissue or organ removed from an animal treated with a drug, tested in vitro
• How are concentrations expressed in in vitro experiments?


  In Moles per litre, i.e., Molar (M)
• What does a 1 Molar solution contain?


  1 Mole of a drug dissolved in 1 litre of solvent
• What is the significance of a 1 Molar solution of different drugs?


  A 1 Molar solution of drug “X” will contain the same number of drug molecules as a 1 Molar solution of drug “Y”
• What is the typical concentration range for most clinically useful drugs?


  1 x 10^{-6} M to 1 x 10^{-12} M
• What prefixes are often used by pharmacologists for concentrations?


  Milli (m), micro (μ), and nano (n)
• How is a drug dose expressed in in vivo experiments?


  As weight of drug per weight of animal, e.g., 1 mg per kg (1 mgkg^{-1})
• What does Emax indicate in a concentration-response curve?


  The maximum response the drug can produce
• What is EC50 defined as?


  The Molar concentration of a drug that produces 50% of the maximum response for that drug
• How can relative potency be quantified?


  Using the EC50 values of two drugs with the same action
• What does a potency ratio (M) indicate?


  The comparison of the EC50 of a test drug to a standard drug
• What is the therapeutic index?


  The ratio between the toxic dose of a drug and the dose producing the desired therapeutic effect
• How is the therapeutic index calculated?

  Therapeutic index = LD50 / ED50
• Why is the therapeutic index difficult to quantify?


  Because there is a wide person-to-person variation in both toxic and beneficial effects of drugs
• What are the key learning outcomes of the lecture?

  • Draw concentration vs response and log concentration vs response curves
  • List common responses to drugs and explain measurement
  • Distinguish between in vitro, in vivo, and ex vivo measurements
  • Explain EC50 and its measurement
  • Distinguish between potency, potency ratio, and relative potency
  • Explain the Therapeutic Index and its measurement