Third year lecture 8

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Third year lecture 8

  1. 1. Medicinal Chemistry Lecture 8
  2. 2. Exam Revision
  3. 3. <ul><li>Receptors and Receptor Site </li></ul>
  4. 4. Continue… <ul><li>Receptor down-regulation: </li></ul><ul><li>A phenomenon whereby an agonist, after binding to a receptor, actually induce a decrease in the number of these receptors available for binding </li></ul><ul><li>Receptor Up-regulation: </li></ul><ul><li>The opposite of the above, involves an agonist-induced increase in the number of receptors. </li></ul>
  5. 5. Continue… <ul><li>Affinity: </li></ul><ul><li>The ability of the drug to combine with a receptor. A ligand of low affinity requires a higher concentration to produce the same effect as a ligand of high affinity. Both agonists and antagonists have affinity for the receptor. </li></ul><ul><li>Efficacy: </li></ul><ul><li>Describe the relative intensity with which agonist vary in the response they produce when occupying the same number of receptors and with the same affinity </li></ul>
  6. 6. Continue… <ul><li>Potency: </li></ul><ul><li>Refers to the dose of a drug required to produce effect of given magnitude as compared to a standard reference. Potency is dependent on both affinity and efficacy. </li></ul><ul><li>Tolerance: </li></ul><ul><li>Decrease of the intensity of the response to a given dose over time </li></ul>
  7. 7. Stereochemistry of Drug Action
  8. 8. Structurally Rigid Groups
  9. 12. The influence of configuration on ADME <ul><li>Absorption: </li></ul>
  10. 13. <ul><li>Active Transport: </li></ul><ul><li>(-)Norgestrel is absorbed at twice the rate of (+)Norgestrel </li></ul><ul><li>L-Dopa is more rapidly absorbed in comparison to D-Dopa </li></ul><ul><li>Passive diffusion: </li></ul><ul><li>No difference in absorption between enantiomers </li></ul><ul><li>Racemates may be absorbed at a rate that is different to their pure individual enantiomers </li></ul>
  11. 14. Distribution <ul><li>Stereoselectivity appears to have little influence on the transport of stereoisomers through the circulatory system. </li></ul><ul><li>Some enantiomers prefer to bind to a specific plasma protein (R-Propanalol prefers to bind to human albumin while S-Propanalol prefers alpha-acid glycoproteins) </li></ul>
  12. 15. Metabolism
  13. 16. <ul><li>S-Indacrinone plasma half-life is 2-5 hours </li></ul><ul><li>R-Indacrinone plasma half-life is 10-12 hours </li></ul>
  14. 17. Extraction <ul><li>Modest stereoselectivity has been reported in the renal excretion of these drugs </li></ul>
  15. 18. Next Lecture <ul><li>Drug Metabolism </li></ul>
  16. 19. <ul><li>THE END </li></ul>

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