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Second lec& 3rd

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  • جزاك الله كل الخير على سلسلة محاضرات الكيمياء الطبية

    هنل هناك كتاب باللغة العربية للكيمياء الطبية ؟

    هل هذه الساليدات لجامعة سعودية ؟



    سبحان الله وبحمده سبحان الله العظيم
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Second lec& 3rd

  1. 2. <ul><li>Physicochemical Properties of Drugs </li></ul><ul><li>The Effect of pH and pKa on Drug Action </li></ul>
  2. 3. <ul><li>most drugs are small organic molecules that </li></ul><ul><li>behave in solution as either weak acids or weak bases. </li></ul><ul><li>Acid-Base properties of drugs greatly influences their biodistribution and partitioning characteristics. </li></ul><ul><li>What does it mean to say that a certain molecule is an acid or base? </li></ul><ul><li>Arrhenius definition. </li></ul>
  3. 11. and Base Strength ِ Acid ِ
  4. 17. Percentage Ionization
  5. 19. Example <ul><li>What is the ratio of ephidrine to ephedrine HCl (pKa 9.6) in the intestinal tract at pH 8.0? </li></ul>
  6. 21. <ul><li>What is the percentage ionization of: 1. ephedrine HCl (pKa 9.6) and 2. indomethacin (pKa 4.5) in an intestinal tract with pH 8? </li></ul>
  7. 22. <ul><li>pKa for the base is the pKa of its conjugate acid. </li></ul><ul><li>Ephedrine pKa =9.6 </li></ul><ul><li>Ammonia pKa=9.3 </li></ul>
  8. 23. <ul><li>What is the significance of Ka and pKa values? </li></ul>
  9. 26. <ul><li>How can the drug pKa value be used? </li></ul>
  10. 27. Rules Acid drugs – become more NON ionized in acidic pH Basic drugs – become more NON ionized in basic pH (alkaline pH) Acid Drug Basic Drug Acid pH Environment Basic pH Environment
  11. 28. Rules Acid drugs – become more NON ionized in acidic pH Basic drugs – become more NON ionized in basic pH (alkaline pH) Acid Drug Basic Drug Acid pH Environment Basic pH Environment NON-ionized NON-ionized
  12. 29. Rules Acid drugs – become more NON ionized in acidic pH Basic drugs – become more NON ionized in basic pH (alkaline pH) Acid Drug Basic Drug Acid pH Environment Basic pH Environment NON-ionized NON-ionized IONIZED
  13. 30. Rules Acid drugs – become more NON ionized in acidic pH Basic drugs – become more NON ionized in basic pH (alkaline pH) Acid Drug Basic Drug Acid pH Environment Basic pH Environment NON-ionized NON-ionized IONIZED IONIZED
  14. 31. Rules Hydrophilic = Ionized molecules (charged) Lipophilic = Non-ionized molecules (non charged) Lipophilic molecules penetrate membranes Hydrophilic molecules dissolve in water
  15. 32. Depending if a molecule is ionized or not determines if it can pass through a cell membrane C E L L M E M B R A N E Ionized Molecule Non-Ionized Molecule
  16. 33. Need three things to figure out whether drug is MAJORITY in lipophilic or hydrophilic form <ul><li>Whether the drug is an acid drug or a base drug. </li></ul><ul><li>The pKa of the drug (pH at which number of ionized = number of nonionized molecules) </li></ul><ul><li>pH into which the drug is going to be placed </li></ul>
  17. 34. Acid Drug = Non ionized molecules = Ionized molecules Acid drugs – become more NON ionized in acidic pH pH 2 N I pH 6 N I pH 9 I pH 8 I N
  18. 35. Basic Drug = Non ionized molecules = Ionized molecules Basic drugs – become more NON ionized in basic pH pH 9 N I pH 8 N I pH 2 I pH 6 I N
  19. 36. WHEN GIVEN: <ul><li>Acid / Base nature of the drug </li></ul><ul><li>Drug’s pKa </li></ul><ul><li>Environmental pH drug is put into </li></ul><ul><li>Be able to predict whether majority of drug is in the ionized form or non-ionized form </li></ul><ul><li>Be able to state whether majority of drug is in the hydrophilic form or lipophilic form </li></ul><ul><li>Be able to predict whether it can be absorbed across membrane or dissolved in water </li></ul>
  20. 37. <ul><li>Examples </li></ul>
  21. 38. Carboxylic Acids
  22. 40. Phenols
  23. 43. <ul><li>The End </li></ul>

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