Liposomes are spherical vesicles made of phospholipid bilayers that can encapsulate aqueous solutions. They range in size from 20nm to several microns. Liposomes can be used to deliver drugs as they protect drugs from degradation and can target delivery to specific tissues. There are several types of liposomes classified by their structure, size, number of bilayers, and method of preparation. The main components used to form liposome bilayers are phospholipids like phosphatidylcholine and cholesterol. Liposomes offer advantages for drug delivery such as passive targeting to tumors, reduced toxicity, and improved pharmacokinetics.

1. Dr. Subhash V. Deshmane
Associate Professor
Rajarshi Shahu College of Pharmacy
Buldana. M.S. India
www.rscp.ac.in
Email: subdeshmane@yahoo.co.in

2. WHATARE LIPOSOMES?
 Liposomes are simple microscopic
vesicle
in which an aqueous volume is entirely
enclosed by a membrane composed of a
lipid molecule.
 Structurally, liposomes are concentric bil
ayered vesicles in which an aqueous
volume is entirely
enclosed by a membraneous
lipid bilayer mainly composed of natural
or synthetic phospholipids.
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Hydrophilic
Hydrophobic

3. LETS TAKE A LOOK AT A LIPOSOME
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Hydrophobic
Hydrophilic
cavity

4. Why Use Liposomes in Drug Delivery?
 DrugTargeting
 Inactive: Unmodified liposomes gather in
specific tissue reticuloendothelial system
 Active: alter liposome surface with
ligand (antibodies, enzymes, protein A,
sugars).
 Physical: temperature or pH sensitive
liposomes
 Directly to site
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5.  Pharmacokinetics - efficacy and toxicity
 Changes the absorption and
biodistribution
 Deliver drug in desired form
 Protection
 Decrease harmful side effects
 Protects drug
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6. ADVANTAGESOFLIPOSOMES
 Provides selective passive targeting to tumor tissues
(liposomal doxorubicin) (in short tissue targetting).
 Increased efficacy and therapeutic index
 Reduction in toxicity of the encapsulated agent
 Site avoidance effect (avoids non-target tissues)
 Improved pharmacokinetic effects (reduced
elimination increased circulation life times)
 Flexibility to couple with site-specific ligands to achieve
active targeting.
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7. STRUCTURAL COMPONENTS OF LIPOSOMES
 THE MAIN COMPONENTS OF LIPOSOMESARE:-
 PHOSPHOLIPIDS
 CHOLESTEROL
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8. PHOSPHOLIPIDS
Phospholipids are the major structural components of
biological membranes such as the cell membrane.
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TWO TYPES OF
PHOSPHOLIPIDS (ALONG
WITH THEIR
HYDROLYSIS PRODUCTS)
PHOSPHOGLYCERIDES
SPHINGOLIPIDS

9. Phosphatidylcholine
 Most common phospholipid used is
phosphatidylcholine (PC).
• Phosphatidylcholine is an amphipathic
molecule in which exists
– a hydrophilic polar head group,
phosphocholine.
– a glycerol bridge
– a pair of hydrophobic acyl hydrocarbon
chains
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10. Generally phospholipids are represented as
follows:
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11.  Molecules of PC are not soluble in water.
 In aqueous media they align themselves closely in
planar bilayer sheets in order to minimize the
unfavorable action between the bulk aqueous
phase and the long hydrocarbon fatty chain.
• Such unfavorable interactions are completely
eliminated when the sheets fold on themselves to
form closed sealed vesicles
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12. In short this is what happens
07/12/2009SNIOP COLLEGE OF PHARMACY, PUSAD PRESENTED BY- S.R. SHIMBRE 12

13. SOME OTHER COMMONLY USED
PHOSPHOLIPIDS
 Naturally occurring phospholipids:
-PC : Phosphatidylcholine
– PE : Phosphatidylethanolamine
– PS : Phosphatidylserine
 Synthetic phospholipids:
-DOPC : Dioleoylphosphatidylcholine
 – DSPC : Distearoylphosphatidylcholine
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14. CHOLESTEROL
 Incorporation of sterols in liposome bilayer brings
about major changes in the preparation of these
membranes.
 Cholesterol by it self does not form a bilayer structure.
However, cholesterol acts as a fluidity buffer, i.e. below
the phase transition temperature, it makes the
membrane less ordered and slightly more permeable;
while above the phase transition temperature it makes
the membrane more ordered and stable.
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15. Cholesterol inserts into the membrane with its
hydroxyl groups oriented towards the aqueous
surface
and aliphatic chain aligned parallel to
the acyl chains in the center of the bilayer.
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16. TYPES OF LIPOSOMES
 Liposomes are classified on the basis of
– Structural parameters
– Method of preparation
– Composition and applications
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17. What is a lamella?
– A Lamella is a flat plate like structure that appears during
the formation of liposomes.The phospholipid bilayer first
exists as a lamella before getting converted into spheres.
– Several lamella of phospholipid bilayers are stacked one on
top of the other during formation of liposomes to form a multila
mellar structure.
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18. 18
Multilamellar vesiclesUnilamellar vesicles

19. Based on structural parameters
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Based on structural
Based on structural
parameters
MLV
Multilamellar
Large
vesicles
(>0.5 um)
OLV
oligolamellar
vesicles
(>0.1-1.0 um)
UV Unilamellar
Vesicles (all siz
e ranges)
MVV
Multivesicular
vesicles
(> 1.0 UM)
MUV
GUV
>1um
SUV
20-
100nm
LUV
>100nm

20. Based on
method of
preparation
REV, SUV made by
reverse phase
evaporation
method
SPLV
Stable
plurilamenar
vesicles
FATMLV
Frozen
&thawed MLV
VET
Vesicles
prepared by
extrusion
tech.
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21. Methods of liposome preparation
 Passive loading techniques
 Active loading techniques
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22. Passive loading techniques
 Mechanical dispersion methods
 Solvent dispersion methods
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23. mechanical dispersion method
 Hand-shaken multilamellar vesicles
 Non-shaking vesicles
 Pro- liposomes
 Freeze drying
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24. Hand shaken method in
general
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25.  Non-shaking vesicles
 Pro- liposomes
 Freeze drying
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26. Solvent dispersion methods
 Ethanol injection method.
 Ether injection method.
 Reverse phase evaporation vesicles method.
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27. Ethanol/Ether injection method
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28. Reverse phase evaporation vesicles
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At this stage-
the monolayers come
close to each other
In rotar y evaporator close to each other
partial bilayer

29. REFERENCES:-
 Target & Controlled Drug Delivery Novel
Carrier Systems by S. P.Vyas & R. K. Khar
 Liposomes as drug carriers by Sanjay K Jain
and N K Jain
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30. 07/12/2009SNIOP COLLEGE OF PHARMACY, PUSAD PRESENTED BY- S.R. SHIMBRE 30