This document provides an overview of liposomes, including their structure, advantages, disadvantages, components, preparation methods, characterization, and applications. Liposomes are spherical vesicles composed of phospholipid bilayers that can encapsulate aqueous volume. They were first produced in 1961 and range in size from 20 nm to several micrometers. Liposomes provide benefits like selective targeting to tissues, increased efficacy, reduced toxicity, and improved pharmacokinetics. Common preparation techniques include lipid film hydration, microemulsification, sonication, and detergent removal. Liposomes are characterized based on their physical properties and are used to deliver drugs for diseases like cancer, fungal infections, and more.

1. Liposomes
Presented by,
Pratiksha C
M pharma 2nd SEM
Dept. of pharmaceutics
HSK COP Bagalkot
Facilitated to,
Dr. Anita Desai
HOD and professor
Dept. of pharmaceutics
HSK COP Bagalkot
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2. •Introduction
•Structure of liposomes
•Advantages& disadvantages
•Components of liposome
•Preparation methods of liposomes
•Characterization of liposomes
•Applications of liposomes
•References
2

3. Introduction:
Liposomes are concentric bilayered vesicles in which an aqueous
volume is entirely enclosed by a membraneous lipid bilayer
mainly composed of natural or syntheticphospholipids.
Liposomes were first produced in England in 1961 by Alec D.
Bangham. The size of a liposome ranges from some 20 nm up to
several micrometers
3

4. Hydrophillic head
Hydrophobic tail
The lipid moecules are usually phospholipids-amphipathic
moieties with a hydrophilic head group and two
hydrophobic tails.
Liposome =Phospholipid+
cholesterol
4

5. Advantages of liposomes
1. Provides selective passive targeting to tumor tissues.
(liposomal doxorubicin) .
2. Increased efficacy and therapeutic index.
3. Reduction in toxicity of the encapsulated agent.
4. Site avoidance effect (avoids non-target tissues).
5. Improved pharmacokinetic effects .
6. Flexibility to couple with site-specific ligands to achieve
active targeting.
5

6. Disadvantages of liposomes:
Production cost is high.
Leakage and fusion of encapsulated drug /
molecules.
Sometimes phospholipid undergoes oxidation
and hydrolysis like reaction.
Short half-life.
Low solubility.
6

7. H2O Layer
Polar Lipids
(Phospholipid)
Water Soluble
ingredients
(Drugs, Nutrients
Lipid Soluble
ingredients
(Drugs,Nutrients
& vitamins)
Cross-section of liposomes:
& vitamins)
7

8. components of liposomes:
The structural components of liposomes
include:
A. Phospholipids
B. cholesterol
8

9. Classification of liposome :
Classification
of liposome
Structural
parameters
Based on lamelle Composition and
application
9

10. Types of vesicles based on lamella
Lamella :
10

11. Based on structural parameters
MLV
Multilamellar Large
vesicles (>0.5 um)
OLV
oligolamellar vesicles
(>0.1-1.0 um)
UV
Unilamellar
Vesicles
MVV
Multivesicular vesicles
(> 1.0 UM)
MUV
GUV
>1um
SUV 20-
100nm
LUV
>100nm
11

12. Based on
composition &
application
convential
fusogenic
pH
sensitive
cationic
Long
circulatory
immuno
Based on
composition
and
application:
12

13. Passive
loading
technique
Active/remo
te loading
technique
Loading of the entrapped agents
before/ during the manufacture
procedure.
Certain types of compounds with
ionizable groups & those with both
lipid & water solubility can be
Introduced into liposomes after the
formation of intact vesicles.
MethodS of Liposome Preparation
13

14. Methods of liposome preparation
Passive loading techniques Active loading techniques
Mechanical dispersion
methods
❑ LIPID FILM HYDRATION
BY HAND SHAKING,FREEZE
DRYING OR NON HAND
SHAKING
❑ MICRO EMULSIFICATION
❑ SONICATION
❑ FRENCH PRESSURE CELL
❑ MEMBRANE EXTRUSON
❑ DRIED RECONSTITUTED VESICLES
Solvent dispersion
methods
❑ ETHANOL INJECTION
❑ ETHER INJECTION
❑ DOUBLE EMULSION
❑ REVERSE PHASE
VAPOURATION VESICLES
❑ STABLE PLURI LAMELLER VESICLES
Detergent removal
technique
14

15. General Method Of Liposome
Preparation:
2315

16. Liposome
Post Hydration vortexing, sonication, freeze thawing &
high pressure extrusion
Lipid dissolve in organic solvent/co-solvent
Remove organic solvent under vacuum
Film deposition
Solid lipid mixture is hydrated by using aqueous buffer
Lipid spontaneously swell & Hydrate
1. Mechanical dispersion method:
2416

17. There are four basic methods of physical/mechanical
dispersion :
Hand shaken method.
Non shaking method.
Pro – liposomes .
Freeze drying .
17

18. Lipids form stacks of film
from organic solution
(FE/HS)
Then film is treated with
aqueous medium
Upon hydration lipids
swell and peel out from
RB flask
vesiculate to form Multi
lamellar vesicles(MLVs)
18

19. Pro-liposomes:
✓ To increase the surface area of dried lipid film &
to facilitate instantaneous hydration.
lipid Dried
over
lipid
Finely divided
particulate support
like powdered NACL/
sorbital
Pro - liposomes
Pro-
liposomes
water
Dispersion of MLV’S
✓This Method overcome the stability problem. 2719

20. Membrane extrusion Liposomes
Dried reconstituted vesicles(DRVs)
Freeze thaw sonification (FTS)
pH induced vesiculation
Cochleate method.
Processing of the lipids hydrated by physical means or the
mechanical treatments of MLVs :
Micro Emulsification liposomes (MEL)
Sonicated unilamellar vesicles (SUVs)
French Pressure Cell Liposomes .
2820

21. Sonicated unilamellar vesicles:
The exposure of MLVs to ultrasonic
irradation for producing small vesicles.
Bath sonicator
large volume
of dilute lipids
Probe sonicator
Used for dispersions
require high
energy in
small volumes
Sonication
MLVs hazy transparent
5-10 min solution
centrifugation 30 min
clear SUV
Dispersion.
2921

22. Micro emulsification liposomes:
Micro fluidizer 3022

23. French pressure cell liposomes:
Extrusion of preformed large liposomes in french press under very
high pressure .
uni or oligo lamellar liposomes of intermediate size (30-80nm ) .
Advantages
Less leakage and more stable liposomes
are formed compared to
sonicated forms 3123

24. Vesicles prepared by extrusion technique :
The size of liposomes is
reduced by gently passing them
through polycarbonate
membrane filter of defined
pore size at lower pressure
Used for preparation of LUVs
and MLVs
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25. Dried reconstituted vesicles& freeze thaw sonication method
25

26. pH induced vesiculation:
Preformed
MLV’S
(2.5-3.0)
~ (addition of 1M
NaoH)
~Period of
exposure < 2min
Reduced the pH
to 7.5
Exposed to high pH * Addition of
0.1M Hcl
The transient change in pH brings about
an increase in surface charge of the lipid
bilayer which induces spontaneous
vesiculation .
MLVs
LUVs
26

27. SUVs made
from
phosphatidylse
rine(PS)
Addition of
Ca++ ions
Cylindrical
rolls(cochleate
cylinders)
Removal
of Ca++by
EDTA
Cochleate method:
Cochleates
27

28. Lipid dissolve in organic solvent
Excess addition of aqueous phase
Lipids allign at interface of aqueous and organic layer
Formation of monolayer and bilayer of phospholipids
Liposome
Note:- Organic solvent miscible with aqueous phase
Solvent dispersion methods:
28

29. Solvent dispersion methods:
ETHANOL INJECTION/ETHERINJECTION:
29

30. De-Emulsification method:
Generally the liposome is made up in 2 steps:
1 st the inner leaflet of the bilayer .
Then the outer half.
~Reverse phase evaporation vesicles
~Sonication methods
Aqueous medium
containing material
to be entrapped
Add to immiscible
organic solution of
lipid
Mechanical agitation
Microscopic water
droplets
Methods to prepare the droplets:
~Double emulsion vesicles
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31. Reverse phase evapouration method:
31

32. Phospholipid brought into intimate contact with
aqueous phase
By addition optimized concentration of detergent
Formation of micelles (Liposome)
shape depend on chemical
nature of
detergent, concentration and
other lipid involved
Below CMC, detergent molecules exist in free soln. As the
concentration is increased, micelles areformed.
Note:- Liposome size and
DETERGENT SOLUBILISATIOIN METHODS
Methods to remove detergents:
Dialysis
Column chromatography.
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33. Active/remote loading technique:
The lipid bilayer membrane is impermeable to ions & hydrophilic
molecules. But, Permeation of hydrophobic molecules can be controlled
by concentration gradients.
Some weak acids or bases can be transported due to various
transmembrane gradients
Electrical gradients.
Ionic(pH) gradients.
Chemical potential gradients.
Weak amphipathic bases accumulate in aq phase of lipid vesicles
in response to difference in pH b/w Inside & outsideof
liposomes 33

34. pH gradient is created by preparingliposomes
with low internal pH.
Addtn of base to extraliposomal medium.
[Basic compds ( lipophilic (non ionic) athigh
pH & hydrophilic(ionic) at lowpH)]
Lipophilic (UNPROTONATED) drug diffuse through
thebilayer
At low pH side, the moleculesare
predominantly protonated .
Exchange of external medium by gelextrusion
chromatorapghy with neutralsolution.
Weak bases like doxorubicine,
adriamycin and vincristine are
encapsulated.
Solute bearing no
charge at neutral pH
Liposomes with low
internal pH
Neutral solute passes
easily through bilayer
membrane by diffusion
Charge aquired by solute
inside liposomes makes
them unable to exit
34

35. Characterization of liposomes:
PHYSICAL CHARACTERISATION
→ Vesicles size/shape/morphology
→ Surface -charge/electrical potential
→ Phase behaviour/ lamellarity
→ Drug release
→ % capture /free drug
CHEMICA L CHARACTERISATION
→ Phospholipids /lipid concentration
→ Drug concentration
→ PH / Osmomolality
→Antioxidant degradation
→ Phospholipids / cholesterols –
peroxidation/oxidation/hydrolysis
BIOLOGICAL CHARACTERISATION
→ Sterility
→ Pyrogenisity
→ Animal toxicity
→Plasma Stability:
35

36. Characterization parameters Analytical method/Instrument
1. Vesicle shape and surface morphology Transmission electron microscopy,Freeze-
fracture electron microscopy
2.Mean vesicle size and size distribution
(submicron and micronrange)
Photon correlation spectroscopy, laserlight
scattering, gel permeation and gelexclusion
3. Surface charge Free-flow electrophoresis
4. Electrical surface potential and surfacepH Zetapotential measurements
5. Lamellarity Small angle X-ray scattering, 31 P-NMR,Freeze-
fracture electron microscopy
6. Phase behavior Freeze-fracture electron microscopy, Differentialscanning
calorimetery
7. Percent of free drug/ percentcapture Minicolumn centrifugation, ion-exchange
chromatography, radiolabelling
8. Drug release Diffusion cell/ dialysis
36

37. Characterization parameters Analytical method/Instrument
1. Phospholipid concentration Barlett assay, stewart assay, HPLC
2. Cholesterol concentration Cholesterol oxidase assay and HPLC
3. Phopholipid peroxidation UV absorbance
4. Phospholipid hydrolysis,
Cholesterol auto-oxidation.
HPLC and TLC
5. Osmolarity Osmometer
37

38. Characterization parameters Analytical method/Instrument
1. Sterility Aerobic or anaerobic cultures
2. Pyrogenicity Limulus Amebocyte Lysate (LAL) test
3. Animal toxicity Monitoring survival rates, histologyand
pathology
STABILITY OF LIPOSOMES:
❖Stability invitro .
~ Lipid oxidation
~ Lipid peroxidation
~ Long term & accelerated stability
❖Stability after systemic administration.
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39. In gene delivery.
As drug delivery carriers.
Enzyme replacement therapy.
Chelation therapy for treatment of heavy metal poisoning.
Liposomes in antiviral/anti microbial therapy.
In multi drug resistance.
In tumour therapy.
In immunology.
In cosmetology
39

40. DRUG ROUTE OF
ADMINISTRATION
APPLICATION TARGETED DISEASES
Amphotericin B Oral delivery Ergosterol membrane Mycotic infection
Insulin Oral,ocular,pulmonary
And transdermal
Decrease glucoselevel Diabetic mellitus
Ketoprofen Ocular delivary Cyclooxygenase enzymeinhibitor Pain muscle condition
Pentoxyfyllin Pulmonary delivery phosphodiesterase Asthama
Tobramycin Pulmonary delivery Protein synthesisinhibitor Pseudomonas
infection,aeroginosa
Salbutamol Pulmonary delivery ß2-adrenoceptor antagonist Asthama
Cytarabin Pulmonary delivery DNA-polymeraseinhibition Acute leukameias
Benzocaine Transdermal Inhibition of nerve impulsefrom
sensory nerves
Ulcer on mucoussurface
with pain
Ketaconazole Transdermal Inhibit ergosterolmembrane Candida albicans
Levanogesterol Transdermal Rhamnosereceptor skin disorder
hydroxyzine Transdermal H1-receptorantagonist Urtecaria,allergic skin
disease
Ibuprofen Oral delivery Chaemoceptor,freeending Rheumatoidarthritis
triamcilonone Ocular delivery,Transdermal Inhibition of prostaglandin Anti-inflammatory
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41. NAME TRADE NAME COMPANY INDICATION
Liposomal
amphotericinB
Abelcet Enzon Fungal infections
Liposomal
amphotericinB
Ambisome Gilead Sciences Fungal and protozoalinfections
Liposomal cytarabine Depocyt Pacira(formerly
SkyePharma)
Malignant lymphomatousmeningitis
Liposomal
daunorubicin
DaunoXome Gilead Sciences HIV-related Kaposi’s sarcoma
Liposomal doxorubicin Myocet Zeneus Combination therapy with cyclophosphamide in
metastatic breastcancer
Liposomal IRIV vaccine Epaxal Berna Biotech Hepatitis A
Liposomal IRIV vaccine Inflexal V Berna Biotech Influenza
Liposomal morphine DepoDur SkyePharma, Endo Postsurgical analgesia
Liposomal verteporfin Visudyne QLT,Novartis Age-related macular degeneration,pathologic
myopia, ocular
histoplasmosis
Liposome-PEG
doxorubicin
Doxil/Caelyx Ortho Biotech,
Schering-Plough
HIV-related Kaposi’s sarcoma, metastaticbreast
cancer, metastatic
ovarian cancer
Micellular estradiol Estrasorb Novavax Menopausal therapy 41

42. 1. S.P. Vyas And R.K. Khar,targeted & Controlled Drug
Delivery,liposomes,173-279.
2. Mohammad Riaz, Liposomes :Preparation Methods, Pakistan
Journal Of Pharmaceutical Sciences, January 1996,Vol.19(1),65-
77.
3. Sharma Vijay K1*, Liposomes: Present Prospective and Future
Challenges,International Journal Of Current Pharmaceutical
ReviewAnd Research, oct 2010,vol1, issue 2,6-16
4. Himanshu Anwekar*, Liposome- as drug carriers,
International Journal Of Pharmacy & LifeSciences,Vol.2,
Issue 7: July: 2011, 945-951.
5. Jain NK. Introduction to novel drug delivery systems.1st
edition. Vallabh Prakashan publishers;2010.
6. Dr. Baviskar DT, Dr. Jain DK. Novel drug delivery systems.
2nd edition. Nirali Prakashan publishers;2015.
7. Images are from google.
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