Liposomes: Improving drug delivery

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Liposomes: Improving drug delivery

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Liposomes: Improving drug delivery

  1. 1. Liposomes: Improving drug delivery<br />
  2. 2. What is a liposome?<br />Liposomes are closed vehicles having both lipophilic and hydrophilic portions.<br />Size range is from 25nm to as much as 10mm.<br />Made from naturally occuring phospholipids such as phosphatidylcholine , cholesterol.<br />Also obtained from synthetic phospholipids like phosphatidylinositol.<br />
  3. 3. Structure of liposome<br />Hydrophilic<br />Hydrophobic<br />Spherical vesicles with a phospholipidbilayer<br />
  4. 4. Cell Membrane<br />
  5. 5. Advantages of Liposomes<br />They can incorporate both hydrophobic and hydrophilic drugs in them.<br />Their surfce can be modified to alter their biodistribution and pharmakokinetics.<br />Alter drug distribution according to their size.<br />Liposomes can be made to release the entrapped drugs at increased temperatures.<br />
  6. 6. Advantages of Liposomes<br />A number of anticancer and anti-microbiologic agents such as Cytosine, Arabinoside, Methotrexate, Doxorubicin, Dactinomycin and AmphotericinB are entrapped.<br />These can be grafted with hydrophilic polymers such as PEG to reduce their uptake by macrophages.<br />
  7. 7. Why Use Liposomes in Drug Delivery?<br />Pharmokinetics - efficacy and toxicity<br /><ul><li>Changes the absorbance and biodistribution
  8. 8. Deliver drug in desired form
  9. 9. Multidrug resistance</li></ul>Protection<br /><ul><li>Decrease harmful side effects
  10. 10. Change where drug accumulates in the body
  11. 11. Protects drug</li></li></ul><li>Why Use Liposomes in Drug Delivery?<br />Release<br /><ul><li>Affect the time in which the drug is released
  12. 12. Prolong time -increase duration of action and decrease administration</li></ul>Dependent on drug and liposome properties:<br /><ul><li>Liposome composition, pH and osmotic gradient, and environment</li></li></ul><li>Targeted Liposome delivery system<br />
  13. 13. Preparation of targeted Liposomes<br />
  14. 14. Modes of Liposome/Cell Interaction <br />Adsorption<br />Endocytosis<br />Fusion<br />Lipid <br />
  15. 15. Medical Applications of Liposomes<br />Chelation therapy for treatment of heavy metal poisoning<br />Enzyme replacement<br />Diagnostic imaging of tumors<br />Cosmetics<br />Study of membranes<br />Localised delivery of drug is possible.<br />
  16. 16. Medical Applications of Liposomes<br />Used for tumor imaging.<br />Ligand mediated targeted drug delivery by long circulating liposomes.<br />Antibodies can be conjugated to PEG chains on PEG stabilized liposomes.<br />To treat artherosclerosis or neointimal hyperplasia.<br />For targeted gene delivery to specific cells.<br />

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