FULL DETAIL ABOUT LIPOSOMES

1. BY BUDDHIPRAKASH
M.PHARM(PHARMACEUTICS)

2.  Introduction.
 Mechanism.
 Composition of liposomes.
 Classification.
 Method of liposome preparation.
 Mechanical dispersion method.
 Solvent dispersion method.
 Detergent removal method.
 Application.
 Advantage.
 Disadvantage.

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 .

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.

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.

7.  Small Unilamellar Vesicles (SUV)- 20 nm - 100 nm, single
lamellae.
 Large Unilamellar Vesicles (LUV)- 100 nm – 400 nm, single
Lamellae.
 Giant Unilamellar Vesicles (GUV)-1 µm and Larger, single
Lamellae.
 Large Multilamellar Vesicles (MLV)-200 nm – 3 µm, multiple
lamellae.

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.

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)

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.

12. 1. Ether injection (solvent vaporization)
2. Ethanol injection.
3. Reverse phase evaporation method.

13. 1. Dialysis.
2. Detergent (cholate , alkyl glycoside, Triton X-100)
removal of mixed micelles (absorption)
3. Gel-permeation chromatography .
4. Dilution.

14. 1. Drug delivery vehicles.
2. Tumor therapy.
3. Vaccine carriers.
4. Gene delivery.
5. Cosmetics.

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

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

17. YOU