liposomes-Target specific drug delivery S Panda.pptx

liposomes

1. by Dr. Satyajit Panda ( Asst.Prof .) INSTITUTE OF PHARMACY & TECHNOLOGY, SALIPUR Liposomes

2. Liposomes are microparticulate lipoidal vesicles which are under extensive investigation as a drug carrier for improving the delivery of therapeutic agents. Liposomes were first produced in England in 1961 by Alec D. Bhangham , who was studying phospholipids and blood clotting. It was found that phospholipids combined with water immediately, formed a sphere because one end of each molecule is water soluble, while the opposite end is water insoluble. Water soluble medications added to the water were trapped inside the aggregation of hydrophobic ends; fat-soluble medications were incorporated into the phospholipid layer. INTRODUCTION:

3. What is a liposome? Liposomes are concentric bilayered vesicles in which an aqueous volume is entirely enclosed by a membranous lipid bilayer mainly composed of natural or synthetic phospholipids.

4. Cell Membrane

5. LAMELLA Unilamellar vesicle Multilamellar vesicle Lamella is a flat plate like structure that appears during the formation of liposomes . The phospholipids bilayer first exists as a lamella before getting converted into spheres. Several lamella of phospholipids bilayers are stacked one on top of the other during formation of liposomes to form a multilamellar structure.

6. The main components of liposomes are :- 1. Phospholipids 2. Cholesterol Classification of phospholipids Natural : ( e.g. Phosphatidyl choline, Phosphatidyl ethanolamine, Phosphatidyl linositol etc ) Modified : (To reduce unsaturation, e.g. Hydrogenated phosphatidyl choline ) Semisynthetic : (e.g. Dipalmitoyl phosphatidyl glycerol) Synthetic : (e.g. Dioleoyl phosphatidyl choline, Dioleoyl phosphatidyl ethanolamine ) Phospholipids with non-natural(Head) groups : PEG chains attached to phosphatidyl ethanolamine STRUCTURAL COMPONENTS

7. Phospholipids

8. • Most common phospholipids used is phosphatidylcholine ( PC ). ( sources : such as egg yolk or soybeans, from which they are mechanically or chemically extracted using hexane) Phosphatidylcholine is an amphipathic molecule in which exists:- a hydrophilic polar head group, phosphocholine. a glycerol bridge. a pair of hydrophobic acyl hydrocarbon chains. 8 pHOSPHATIDYLCHOLINE

9. Fig Compositional Structure of Liposome

10. Cholesterol by itself does not form bilayer structure. Cholesterol is added to form bilayer structure by incorporating it into the phospholipid membrane in very high concentration up to 1:1 or 2:1 ( cholesterol:phopholipid ). It fills in empty spaces among the phospholipid molecules. It acts as fluidity buffer , i.e. decreases fluidity or microviscosity of bilayer . After intercalation with phospholipid molecules alter the freedom of motion of carbon molecules in the acyl chain. It reduces the permeability of the membrane to water soluble molecules. It stabilizes the membrane in the presence of biological fluids such as plasm a.( This effect used in formulation of i.v . liposomes ) Charge molecule : Sometimes liposomes induced with a charge to improve their absorption . Diacyl glycerol, stearyl amine and diacetyl phosphate have been incorporated in the liposomes so as to impart either a positive or negative charge to these structures.

11. CLASSIFICATION Liposomes are classified on the bases of- Structural parameter Method of preparation Composition and application Conventional liposome Specialty liposome

12. Types of liposomes Structure MLV (Multilamellar vesciles) (300-5000nm) OLV ( Oligo lamell ar vesciles) (0.1-1.0µm) Based on structural parameters :

13. ULV (Unilamellarvesciles) ( all size range) a. MUV (Medium unilamellar vesciles) b. SUV (Small unilamellar vesciles ) ( 20-100nm) c. GUV (Giant unilamellar vesciles ) (> 1.0µm)

14. d. LUV (Large unilamellar vesciles) ( 0.1-1µm ) MVV (Multivascular vesciles) (>1.0µm)

15. Based on method of preparation : Method of preparation Types of preparation Single or oligo lamellar vesicle made by reverse phase evaporation method REV Multi lamellar vesicle made by reverse phase evaporation method MLV-REV Stable pluri lamellar vesicle SPLV Frozen and thawed multi lamellar vesicle FATMLV Vesicle prepared by extrusion technique VET Dehydration- Rehydration method DRV

16. Based upon composition & application : Type of Liposome Abbreviation Composition Conventional liposome CL Neutral or negatively charge phospholipids and cholesterol Fusogenic liposome RSVE Reconstituted sendai virus envelops pH sensitive liposomes _ Phospholipid such as phosphatidyl ethanolamine or dioleyol phosphatidyl ethanolamine Cationic liposome _ Cationic lipid with DOPE ( dioleyol phosphatidyl ethanolamine) Long circulatory liposome LCL Neutral high temp, cholesterol, and 5- 10% PEG, DSP Immuno liposome IL CL (conventional) or LCL (long circulatory liposomes (Stealth) ) with attached monoclonal antibody or recognition sequences

17. 1- Stabilize natural lecithin (PC) mixtures 2- Synthetic identical, chain phospholipids 3- Glycolipids containing liposome Based Upon Specialty Liposome 1- Bipolar fatty acid 2- Antibody directed liposome. 3- Methyl/ Methylene x- linked liposome. 4- Lipoprotein coated liposome. 5- Carbohydrate coated liposome. 6- Multiple encapsulated liposome. Based Upon Conventional Liposome

18. Provide controlled drug delivery Biodegradable, biocompatible, flexible Non ionic Can carry both water and lipid soluble drugs Drugs can be stabilized from oxidation Improve protein stabilization Provide sustained release Targeted drug delivery or site specific drug delivery (Flexibility to couple with site specific ligands to achieve active targetting ) Stabilization of entrapped drug from hostile environment Alter pharmacokinetics and pharmacodynamics of drugs (reduced elimination increased circulation life times) Can be administered through various routes Can incorporate micro and macro molecules Act as reservoir of drugs Therapeutic index of drugs is increased Site avoidance effect ( avoids non- target tissues). Can modulate the distribution of drug Reduction in toxicity of the encapsulated agent. ADVANTAGES

19. Less stability Short half life High production cost Quick uptake by cells of R.E.S Allergic reactions may occur to liposomal constituents Very high production cost Drug leakage/ entrapment/ drug fusion Sterilization Short biological activity / t ½ Oxidation of bilayer phospholipids and low solubility Rate of release and altered bio distribution Extensive clinical and laboratory research to a certain long circulating liposomes Repeated i.v . administration problems DISADVANTAGES

20. Liposome Preparation Lipid in organic solvent solution Evaporation Lipid film Hydrate Freeze/thaw cycles Extrusion (or sonication ) Liposomes Gel filtration Purified liposomes

21. Liposome Preparation contd.

22. Liposome Preparation contd.

23. Liposome Preparation contd.

24. FRENCH PRESSURE CELL It is capable of disrupting  cell  walls while leaving the  cell  nucleus undisturbed. The  French press  was invented by Charles Stacy French  of the Carnegie Institution of Washington. The  press  uses an external hydraulic pump to drive a piston within a larger cylinder that contains the liquid sample.

25. SONICATION METHOD Bath sonication  A cylinder with liposome dispersion placed into the bath sonicator .  Easy to control the temperature as compare to the using probe Probe sonication The tip is directly engrossed into the liposome dispersion.  Energy input in this method is very high.  The coupling of energy at the tip result in local hotness therefore the vessel must be engrossed into the cold water or N2.

26. MEMBRANE EXTRUSION METHOD

27. FREEZE THAW LIPOSOMES & DRIED RECONSTITUTED VESICLES

28. ETHANOL & ETHER INJECTION METHOD

29. REVERSE PHASE EVAPORATION VESICLES

30. Liposome characterization Physical characterization

31. Chemical characterization

32. Biological characterization

33. Uses of Liposomes . • Liposomes as drug or protein delivery vehicles. • Liposome in antimicrobial, antifungal(lung therapeutics) and antiviral (anti HIV) therapy. • In tumor therapy. • In gene therapy. • In immunology. • Liposomes as artificial blood surrogates. • Liposomes as radiopharmaceutical and radio diagnostic carriers. • Liposomes in cosmetics and dermatology.

34. Why Use Liposomes in Drug Delivery? Inactive: Unmodified liposomes gather in specific tissue reticuloendothelial system Active: alter liposome surface with ligand (antibodies, enzymes , protein , sugars) Directly to site Physical: temperature or pH sensitive liposomes Drug Targeting

35. Protection Decrease harmful side effects Pharmokinetics - efficacy and toxicity Changes the absorbance and biodistribution Change where drug accumulates in the body Deliver drug in desired form Why Use Liposomes in Drug Delivery?

36. Release Affect the time in which the drug is released Prolong time -increase duration of action and decrease administration Dependent on drug and liposome properties Liposome composition, pH and osmotic gradient, and environment Why Use Liposomes in Drug Delivery?

37. Modes of Liposome/Cell Interaction Adsorption Endocytosis Fusion Lipid transfer

38. Current liposomal drug preparations Type of Agents Examples Anticancer Drugs Anti bacterial Antiviral DNA material Enzymes Radionuclide Fungicides Vaccines *Currently in Clinical Trials or Approved for Clinical Use Malaria merozoite , Malaria sporozoite Hepatitis B antigen, Rabies virus glycoprotein Amphotericin B * In-111 * , Tc-99m Hexosaminidase A Glucocerebrosidase , Peroxidase Duanorubicin , Doxorubicin * , Epirubicin , Methotrexate , Cisplatin * , Cytarabin Triclosan , Clindamycin hydrochloride, Ampicillin, peperacillin , rifamicin AZT cDNA - CFTR *

39. THANK YOU