Liposome

FULL DETAIL ABOUT LIPOSOMES

1. BY BUDDHIPRAKASH M.PHARM(PHARMACEUTICS ) LIPOSOMES

2. Introduction. Mechanism. Composition of liposomes. Classification. Method of liposome preparation. Mechanical dispersion method. S olvent dispersion method. Detergent removal method. Application. Advantage. Disadvantage. Content

3. A  liposome  is a spherical  vesicle  having at least one  lipid bilayer . Liposomes are small artificial vesicles of spherical shape that can be created from cholesterol and natural non-toxic phospholipids.  The word  liposome  derives from two Greek words:  lipo  ("fat") and  soma  ("body") . Liposomes were first described by British haematologist   Alec D Bangham  in 1961  . Liposomes

4. PICTURE OF LIPOSOME

5. Liposomes (lipid vesicles) are formed when thin lipid films or lipid cakes are hydrated and stacks of liquid crystalline bilayers become fluid and swell. The hydrated lipid sheets detach during agitation and self-close to form large, multilamillar vesicles (LMV) which prevents interaction of water with the hydrocarbon core of the bilayer at the edges.  Mechanism

6. Phospholipids - Phospholipids are the main component of the liposome's membrane. The phospholipids used in liposomes are further categorized into natural and synthetic phospholipids. The most common phospholipid used is known as lecithin (also known as phosphatidylocholine) and is amphipathic . Cholestorol - Cholesterol molecules in the membrane increases separation between choline head groups which reduces the normal hydrogen bonding and electrostatic interaction. Composition of Liposomes

7. Small Unilamellar Vesicles (SUV) - 20 nm - 100 nm , single lamellae . Large Unilamellar Vesicles (LUV) - 100 nm – 400 nm , s ingle Lamellae . Giant Unilamellar Vesicles (GUV) - 1 µm and Larger , s ingle Lamellae . Large Multilamellar Vesicles (MLV) - 200 nm – 3 µm , m ultiple lamellae. Classification of Liposomes

8. General method of preparation All the methods of preparing the liposomes involve four basic stages: 1. Drying down lipids from organic solvent. 2. Dispersing the lipid in aqueous media. 3. Purifying the resultant liposome. 4. Analyzing the final product. Methods of liposome preparation

9. FLOW CHART

10. The following methods are used for the preparation of liposome: 1. Passive loading techniques 2. Active loading technique. Passive loading techniques include three different methods: 1. Mechanical dispersion method. 2. Solvent dispersion method. 3. Detergent removal method (removal of non-encapsulated material) Method of liposome preparation and drug loading

11. The following are types of mechanical dispersion methods: 1 . Sonication. 2. French pressure cell: extrusion. 3. Freeze-thawed liposomes. 4. Lipid film hydration by hand shaking, non-hand shaking. 5. Micro-emulsification. 6. Membrane extrusion . Mechanical dispersion method

12. Ether injection (solvent vaporization)  Ethanol injection . Reverse phase evaporation method . Solvent dispersion method

13. Dialysis . Detergent (cholate , alkyl glycoside, Triton X-100) removal of mixed micelles (absorption) Gel-permeation chromatography  . Dilution . Detergent removal method (removal of non-encapsulated material)

14. Drug delivery vehicles . Tumor therapy. Vaccine carriers. Gene delivery. Cosmetics . Applications

15. Liposomes are biocompatible, completely biodegradable, non-toxic, flexible, and non immunogenic . Liposomes are also flexible in their size, and as such they can enclose a wide size range of molecules. Liposomes have both a lipophilic and aqueous environment making it useful for delivering hydrophobic, amphipathic, and hydrophilic medicines. Liposomes can aide with active targeting as it has flexibility in coupling with site-specific ligands. Advantages

16. Liposomes encapsulated drugs require a high production cost. Liposomes may have leakage and fusion of encapsulated drugs. The liposome phospholipid may undergo oxidation and hydrolysis. Liposomes have a shorter half-life. Liposomes have lower solubility . Disadvantages

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