liposomes

1. LIPOSOMES
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Presented by
Dasara Thanmayi

2. ABSTRACT
Liposomes, sphere-shaped vesicles consisting of one or more
phospholipid bilayers, were first described in the mid-60s. Today,
they are a very useful reproduction, reagent, and tool in various
scientific disciplines, including mathematics and theoretical physics,
biophysics, chemistry, colloid science, biochemistry, and biology.
Since then, liposomes have made their way to the market. Among
several talented new drug delivery systems, liposomes characterize
an advanced technology to deliver active molecules to the site of
action, and at present, several formulations are in clinical use.
Research on liposome technology has progressed from conventional
vesicles to ‘second-generation liposomes’, in which long-circulating
liposomes are obtained by modulating the lipid composition, size,
and charge of the vesicle. Liposomes with modified surfaces have
also been developed using several molecules, such as glycolipids or
sialic acid. 2

3. Liposomes are concentric bilayered vesicles in which an aqueous
core is entirely enclosed by a membranous lipid bilayer mainly
composed of natural or synthetic phospholipids.
Liposomes have a size range of 25nm-500nm.
Liposomes are microscopic spheres made from fatty materials,
predominantly phospholipids.
The lipid molecules are usually phospholipids amphiphatic moieties
with a hydrophilic head group and two hydrophobic tails which give
the most thermodynamically stable confirmation.
INTRODUCTION
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4. STRUCTURE OF
LIPOSOME

5. IDEAL PROPERTIES OF LIPOSOMES
Drug loading and control of drug release rate.
Overcoming the rapid clearance of liposomes.
Intracellular delivery of drugs.
Receptor-mediated endocytosis of ligand targeted liposomes.
Triggered release.
Delivery of nucleic acid and DNA.
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6. ADVANTAGES
 Liposomes increases efficacy and therapeutic index of drug.
 Liposomes increased stability via encapsulation.
 They are suitable to give localized action in particular tissues.
 They are bio-degradable, non-immunogenic.
 Liposomes help in reduces the exposure of sensitive tissues to toxic drugs.
 They provide selective passive targeting to tumor tissues
 Liposomes are suitable for controlled release.
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7. DISADVANTAGES
 Production cost of liposomes are very high
 Leakage and fusion of encapsulated drug molecules
 Sometimes phospholipid undergoes oxidation and hydrolysis like reaction.
 Liposomes have short half life.
 Low solubility.
 Difficult in large scale manufacturing and sterilization.
 Possibility of dose dumping due to faulty administration.
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8. PREPARATION OF LIPOSOMES
Active loading technique passive loading technique
Mechanical dispersion solvent dispersion detergent removal technique
a) Lipid-film hydration a) ethanol injection a) detergent removal from
1. Hand shaking b) ether injection vesicles
2. Freeze drying c) double emulsion 1) dialysis
3. Non-hand shaking d)reverse phase 2)column chromatography
4. Pro-liposomes evaporation 3) dilution
b) Micro emulsification
c) Sonication 8

9. HAND SHAKING METHOD
lipids + solvent (choroform : methanol)
in 250ml RBF
Evaporate for 15 min above phase transistion temperature
Flush with nitrogen
Till residue dry
Add 5ml buffer containing material to be entrapped
Rotate flask at room temperature at 60 RPM for 30 min until lipid removes
from wall of RBF.
Milky white dispersion (stand for 2hrs to get MLV)
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10. HAND SHAKING
METHOD

11. NON-SHAKING VESICLES
Lipid + Solvent
Evaporate at room temperature by flow of nitrogen for drying
Add water saturated nitrogen until opacity disappears
Add bulk fluid(drug) & 10-20ml 0.2M sucrose solution to swell
Flush again with nitrogen
Stand for 2hrs at 370c do not disturb for 2 hours
Swirl to yield milky dispersion
Centrifuge at 1200RPM for 10 min at room temperature
MLV on surface is removed
To remaining fluid add iso-osmolar glucose solution and centifuge at 1200RPM
Large unilamellar vesicles are formed
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12. PRO LIPOSOMES
Sorbitol/nacl (increase surface area of lipid film)
+5ml lipid solution(fitted evaporator)
evaporation
again add lipid solution
dry the content using lyophilizer(freeze drayer)
stand over night at room temp
Fluushed with nitrogen for drying properly
MLV formed 12

13. 13

14. FREEZE DRYING
Lipid + solvent (tertiary butanol)
Freeze drying
Add aqueous phase/saline containing drug
Rapid mixing above phase transition temperature
MLV’s
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15. MICRO EMULSIFICATION LIPOSOME
(MEL)
MEL is prepared by the “microfluidizer” which pumps fluid at very
high pressure (10,000 Psi) through a 5µm orifice.
Then it is forced along defined micro channels with direct tow
streams of fluid to colloid together at right angles at very high
velocity.
After a single pass size reduced to a size of 0.1 & 0.2 µm diameter.
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16. SONICATION
Probe sonication:
 the tip of a sonicator is directly engrossed into the liposome dispersion.
 The energy input into lipid dispersion is very high
 the coupling of energy at the tip results in local hotness therefore, the
vessel must be engrossed into a water/ice bath.
Bath sonication:
 the liposomes dispersion is a cylinder is placed into a bath sonicator
 Controlling the temperature of the lipid dispersion is usually easier in
this method, in contrast to sonication by dispersal directly using the tip.
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17. SONICATION

18. SOLVENT DISPERSION
ETHANOL INJECTION
lipid + ethanol solution in syringe
Inject rapidly
In the buffer containing materials to be
entrapped (on heated water bath at
600c)
Small unilamellar vesicles
ETHER INJECTION
lipid + ether solution in syringe
Inject slowly
In the buffer containing materials to be
entrapped (on heated water bath at
34.60c)
Large unilamellar vesicles
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19. Ethanol injection Ether injection
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20. REVERSE PHASE EVAPORATION
Lipid +organic solvent +aqueous solution
Formation of W/O Emulsion
Evaporation under reduced pressure to remove the organic solvent
Lipids form a phospholipid bilayer
Semisolid gel
Shake to get LUV’s
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21. REVERSE PHASE
EVAPORATION

22. DETERGENT REMOVAL METHOD
The micellar dispersion is then subjected to on of the
following methods to remove the detergent:
DIALYSIS: detergents with high CMC (10-20mm) are used that
their removal is facilitated e.g. bile salts-sodium cholate and sodium
deoxycholate , or synthetic detergents like octileglucoside.
COLUMN CHROMATOGRAPHY: by passing dispersion over a
swphadex G-25 column
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23. CHARACTERISATION OF LIPOSOMES
liposomal formulations after their formulation and processing for a
specified purpose are characterized to ensure their predictable in
vitro and in vivo performances
Liposomes produced by different techniques may have different
physicochemical characteristics eg. Sterilization and shelf life
The characterization parameters for the purpose of evaluation could
be classified into 3 broad categories which include physical,
chemical and biological parameters
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24. Size :
various techniques are used to determine the size and size distribution of
liposomes.
 Light scattering technique : it is based on a dynamic laser light scattering . It is
generally based for mono disperse phase. The method relies on algorithms to
determine particles size.
 Optic microscopy : this method is used for the determination of gross size
distribution of large vesicles preparation such as MLV’s . Various methods include
are bright field microscopy phase constant and fluorescent microscopy.
 Electron microscopy: electron microscopy is used to determine size of vesicles , but
this method is especially useful for observing the morphological structure for
liposomes.
 Negative stain electron microscopy : It can provide Important information whether
the liposomes produced are multi (or) unilamellar
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25. Encapsulation efficiency: Protamine aggregation method:
1. Liposome + Protamine = Precipitation
2. Centrifuge (2000 rpm), remove supernatant
3. Liposome pellet + Trion x-100 (surface breaker)
4. The encapsulation efficiency can be determined
(Analytically)
Mini column centrifugation
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26. Applications
Cancer chemotherapy: Liposomes are successfully used to entrap anticancer drugs
This increases circulation life time, protects from metabolic degradation.
Liposomes as carrier of drug in oral treatment : Steroids used for arthritis can be
incorporated into large MLVs. Alteration in blood glucose levels in diabetic was
obtained by oral administration of Iiposome encapsulated insulin.
Drug targeting: the approach for drug targeting via liposomes involves the use of
ligands eg. Antibodies , sugar residues apoprotiens or hormones) which are targeted
on the lipid vesicles. The ligand recognises specific receptor sites and thus causes the
lipid vesicles to concentrate at such target sites.
Topical drug delivery: the application of liposomes on the skin surface has been
proven to be effective in drug delivery into the skin. Liposomes increase the
permeability of skin for various entrapped drugs and at the same time diminish the
side effect of these drugs
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27. Liposome utility Current applications
Solubilisation Amphotericin B , minoxidil.
Size-avoidance Amphotericin B –reduced
nephrotoxicity
Sustained release Anti neoplastic drugs,
corticosteroids.
Drug protection Cytosine arabinose
RES targeting Immunomodulators ,vaccines ,anti
malarials
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28. REFERENCES
Controlled and Novel drug delivery edited by N.K.Jain reprint 2007
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3599573/
https://www.sciencedirect.com/topics/medicine-and-
dentistry/liposome
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