Pharmacology Exam 2

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Pharmacology Exam 2
2010-10-02 00:48:40
Drug Receptor Concept

Drug Receptor Concept I
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  1. Orphan Receptors
    ligands are unknown
  2. Regulatory proteins
    best characterized drug receptors
  3. Other classes of proteins that have been identified as drug receptors
    • enzymes
    • transport proteins
    • structural proteins
  4. Functions of receptors (3)
    • determination of relation between concentration and pharmacologic response
    • regulatory and signaling proteins are significant targets
    • receptors are key determinants of toxicity and efficacy levels of drugs
  5. Increasing a dose will
    eventually plateu
  6. Relationship between drug concentration and its effect (equation)
    E=(Emax X C)/(C+EC50)
  7. EC50
    concentration of drug that produces 50% of the maximal effect
  8. Binding of a drug to a receptor (equation)
    B=(Bmax X C)/(C+Kd)
  9. Kd
    concentration of drug at which half maximal binding occurs
  10. If Kd is low
    binding affinity is high
  11. transduction process that links drug occupancy of receptors and pharmacologic response
  12. Spare receptors
    • more receptors available than needed for a pharmacological response
    • myocardial cells contain a large portion of spare B adrenoreceptors
  13. Sensitivity of a cell or tissue to a particular concentration of agonist depends on
    • Affinity of the receptor for the agonist
    • degree of spareness
  14. Use of the spare receptor concept
    allows one to see the effect of the drug dosage without considering biochemical details of the signaling response
  15. using spare receptor concept to calculate drug concentrations needed (equation)
    (B/Bmax) = (C/[C+Kd])
  16. reduce receptor activity below that observed when there is no ligand present
    inverse agonists
  17. Competitive antagonist
    • occupies some receptors
    • may need more agonist to see effects
  18. Schild equation (concentration of agonist needed in the presence of a competitive antagonist)
    C'/C = 1 + ([I]/Ki)

    • I = fixed concentration of a competitive antagonist
    • Ki = dissociation constant of the antagonist
  19. Schild equation use
    to determine Ki for a competitive antagonist
  20. degree of inhibition produced by a competitive antagonist depends on the concentration of
    the competitive antagonist
  21. clinical response to a competitive antagonist depends on
    the concentration of agonist that is competing for binding receptors
  22. irreversible alpha adrenoceptor antagonist
  23. allosteric modulators
    • bind a separate site on the receptor protein and alter receptor function without inactivating the receptor
    • benzodiazepines
  24. Protamine that is positively charged at physiologic pH can counteract the effects of heparin (negative charge) by binding the drug and making it unavailable. This is an example of:
    Chemical antagonist
  25. Physiologic antagonism
    between endogenous regulatory pathways mediated by different receptors