1. What are 4 ways to regulate a receptor?
    • 1- Desensitization
    • 2- Internalization
    • 3- Upregulation
    • 4- Downregulation
  2. What is desensitization?
    Rapid and reversible process that desensitizes the tissue to any more agonist interaction
  3. True or false, desensitization is reversible
  4. What is Internalization?
    When receptors are recycled via endocytosis in response to an agonist

    Rapid cyling allows for dephosphorylation and increases the rate of restoration of receptors
  5. The binding of beta-arrestin in a beta-adrenergic receptors is an example of which type of receptor regulation?
  6. This process occurs when the receptor is continuously activated from hours to days
  7. What is down-regulation?
    A decrease in the number of receptor molecules in response to an agonist

    It is slow and not readily reversible
  8. This process occurs when the receptor is continuously activated from minutes to hours
  9. This process occurs when the receptor is continuously activated from seconds to minutes
  10. What is tolerance?
    A decrease in the effect (intensity) of the response to a given dose of a drug


    A depletion of substrates required for downstream effects
  11. This process occurs when the receptor is continuously activated for several days
  12. What is up-regulation?
    An increase in the number of receptors in response to pharmacologic antagonists or denervation
  13. Efficacy refers to the ability of the drug to.....
    ....accomplish a specified effect
  14. Potency reflects the amount of the drug.....
    .....required to cause an effect
  15. What two factors determine the approptriate dose of a drug?
    1- max therapeutic efficacy

    2- pharmacologic potency
  16. Image Upload 2
    Which line is the partial agonist?
  17. Image Upload 4
    Which drug is the most potent?
    B (the lowest EC50 value)
  18. Image Upload 6
    Which drug(s) have the highest efficacy?
    A, C, D (highest Emax)
  19. Image Upload 8
    Which drug(s) have the highest efficacy?
  20. Potency refers to the ____ and the ____ values on the graded-dose response curve
    EC50 (concentration)

    ED50 (dose)
  21. Potency of a drug depends on the _____ of the dug for binding to the receptor and the ______ of the occupancy response coupling process
    KD (affinity)

  22. What does the clinical effectiveness of a drug depends on what? (2)
    Emax (max efficacy)

    ability to reach the site of action
  23. When choosing between 2 drugs for administration one must chose based on _____ instead of _____

  24. ________ _________ determines the administered dose of a selected drug
    pharmacologic potency
  25. Drug efficacy in a patient will be determined by? (2)
    1- mode of interactions with the receptor

    2- characteristics of the receptor-effector system
  26. What is the purpose of a quantal dose-response curve?
    It shows the percentage of indiviuals who exhibit a drug effect (toxic, theraputic) vs. log drug dose
  27. _______ is the drug dose where 50% of individuals exhibit the specified quantal effect
    ED50 (median effective dose)
  28. What is TD50?
    Median toxic dose which is the dose required to produce a toxic effect in 50% of the individuals
  29. What is the LD50?
    Median lethal dose which is the dose required to kill 50% of the individuals
  30. What does the therapeutic index measure?
    The estimate of the safety of a drug

    It's the TD50/ED50 ratio
  31. What is the significance of a small therapeutic window?
    It means that the drug is toxic and the levels must be monitored in a patient frequently
  32. What does the therapeutic window (therapeutic range) measure?
    Dosage range between the minimum effective therapeutic dose and the minimum toxic dose
  33. What are the 4 mechanisims known to contribute to variation in drug responsiveness?
    • 1- alteration in concentration at the receptor site
    • 2- variation in concentration of an endogenous receptor ligand
    • 3- alterations in the number of receptors
    • 4- changes in componets of response distal to the receptor
  34. What are the 3 mechanisims for mediating the toxic and beneficial effects of drugs?
    • 1- mediated by the same receptor-effector mechanisim
    • 2- mediated by identical receptors in different tissues
    • 3-mediated by different types of receptors
  35. An unsatistfactory therapeutic response is attributed to the _______ ________ _______ that respond to and oppose the effects of a drug.
    physiologic compensatory mechanisms
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