2. Principle
Definition
Introduction
Biological fate of liposomes
Advantages and limitations
Advancements in liposomes
Stealth liposomes
Pegylation
Composition of liposomes
Mechanism of liposome formation
Classification of liposomes
Methods of preparation
Locus of drugs in liposomes
Characterisation of liposomes
Modes of liposome/cell interaction
Stability of liposomes
Storage of liposomes
Pharmacokinetics of liposomes
Uses of liposomes
Therapeutic applications
List of marketed products 1
Conclusion
3. Targeted Drug Delivery System( liposomes )
must supply drug directly (selectively) to the
site(s) of action in a manner that provides
maximum therapeutic activity through kinetics.
It prevents degradation or inactivation during
transmit to the target sites and protects the
body from adverse reaction because of
inappropriate disposition.
2
4. The name liposome is derived from two Greek
words: 'Lipos' meaning fat and 'Soma' meaning
body.
liposome's are concentric bilayered vesicles in
which an aqueous volume is entirely enclosed
by a membranous lipid bilayer mainly
composed of phospholipids.
3
5. Liposome was found by Alec Bangham of
Babraham Institute in Cambridge, England in
1965
In 1990, drugs with liposome and Amphotericin
B were approved by Ireland.
In 1995 U.S.F.D.A approved liposor doxorubicin .
Liposome is a lipid vesicle suspending in the
aqueous phase with a diameter around
0.0025~3.5um. The membrane of liposome is
made of phospholipids, which have phosphoric
acid sides to form the liposome bilayers .
4
6. Liposomes in Macrophages engulf
Taken by RES liposomes(endocytosis)
blood stream
Membrane of phago
lysosyme also contains
protonpumps which
Release of the drug decrease pH of the Phagosome+lysosome
into cytosol phagolysosyme n the =phagolysosyme
enzymes phospholipases
destruct the liposomal
membrane
5
8. Biocompatible, completely biodegradable, non-
toxic, flexible, nonimmunogenic .
Provides selective passive targetting to tumours.
Liposomes supply both a lipophilic environment and
aqueous in one system. Can protect encapsulated drug.
Increased efficacy and therapeutic index
Reduce exposure of sensitive tissues to toxic drugs.
Alter the pharmacokinetic and pharmacodynamic
property of drugs (reduced elimination, increased
circulation life time ).
Flexibility to couple with site-specific ligands to achieve
active targeting ( Anticancer and Antimicrobial drugs).
Liposomes can encapsulate both micro and
macromolecules such as haemoglobin , erythropoeitin
, interferon g etc .
Can be formulated into multiple dosage forms.
7
9. Production cost is high
Leakage and fusion of encapsulated drug /
molecules.
Sometimes phospholipid undergoes oxidation
and hydrolysis like reaction
Short half-life
Low solubility
Fast elimination from the blood and localisation
in reticuloendothelial system primarily kupffer
cells of liver.
8
10. Ethosomes : efficient at delivering to the
skin.composed of soya phosphotidylcholine + 30%
ethanol.
Immunoliposomes : modified with antibodies.
Niosomes : SUV’s made from nonionic surfactants.
Proliposomes : dry, free flowing particles that
immediately form a liposomal dispersion on contact
with water.
Stealth liposomes : coating of liposomes with
PEG(hydrophilic polymer) to improve Stability &
lengthens their half life in circulation.PEG coating
inhibits recognition by RES system.
9
11. hydrophilic
Coating liposomes with PEG reduces the rate of uptake by
macrophages(stealth effect) and leads to prolonged presence of
liposomes in the circulation and consequently provides ample
time for these liposomes to escape from the circulation through
leaky endothelium.
Liposomes can be composed of naturally derived phospholipids
with mixed lipid chains coated or stabilised by polymers of PEG.
Ex:doxorubicin loaded liposome in market as DOXIL or
CAELYX,treatment of solid tumours.
10
13. Process of construction of stealth liposomes
with PEG studding the outside membrane is
called as pegylation.
Increase in mole% of PEG on surface of
liposomes by 4 to 10% signifantly increased
circulation time invivo from 200-1000 minutes.
12
14. Conventional Long circulating
Immuno
Cationic
24
16. The most common natural phospholipid is the
phosphatidylcholine (PC ).
Naturally occurring phospholipids used in
liposomes are:
Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine
Synthetic phospholipids used in the liposomes
are:
Dioleoyl phosphatidylcholine
Disteroyl phosphatidylcholine
Dioleoyl phosphatidylethanolamine
Distearoyl phosphatidylethanolamine 14
17. Phosphatidylcholine is an amphipathic
molecule in which exists
– a hydrophilic polar head group, phosphocholine .
– a glycerol bridge
– a pair of hydrophobic acyl hydrocarbon chains
Molecules of PC are not soluble in water.
In aq media they align themselves in planar bilayer
sheets inorder to minimize the Unfavorable action b/w
the bulk aq phase & long hydrocarbon fatty chain.
PC molecules contrast with other amphipathic
molecules such as detergents, In that they form
-Bilayer sheets
- not micellar structures
15
18. Cholesterol: Stabilizes the Membrane
Steroid lipid
Interdigitates between phospholipids
i.e. below Tc , it makes membrane less ordered & above
Tc more ordered.
Being an amphipathic molecule, cholesterol inserts into
the membrane with its hydroxyl group of cholesterol
oriented towards the aqueous surface and aliphatic
chain aligned parallel to the acyl chains in the center of
the bilayer
Role of cholesterol in bilayer formation: Restricts the
transformations of trans to gauche Conformations.
Incorporated into phospholipid membrane upto 1:1 or
2:1 of cholesterol to PC.
16
19. TYPES
STRUCTURAL COMPOSITION
METHOD OF
AND
PARAMETERS PREPARATION
APPLICATION
18
21. 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 convered into spheres.
20
31. The procedure differs from hand shaken method in
that it uses a stream of nitrogen to provide agitation
rather than the rotationary movements.
Here the lipid film is exposed to water - saturated
nitrogen(15 – 20min).
After Hydration, lipid is swelled by addition of bulk
fluid. 10-20ml of 0.2M sucrose in distilled
water(degassed) is introduced.
The flask is flushed with nitrogen, sealed and allowed
to stand for 2 hrs at 37 degrees celsius . After
swelling, the vesicles are harvested by swirling the
contents of the flask gently, to yield a
milky‐suspension Centrifugation
LUV 30
32. To increase the surface area of dried lipid film &
to facilitate instantaneous hydration.
Dried over Finely divided particulate
LIPID support like powdered PROLIPOSOMES
NaCl/sorbitol/polysacchari
des
PROLIPOSOMES WATER Dispersion of MLV’s
31
33. Another method of dispersing the lipid in a
finely divided form, prior to addition of aq.
Medium is to freeze dry the lipid dissolved in a
suitable organic solvent.
Tertiary butanol us considered to be the most
ideal solvent.
After obtaining the dry lipid which is a
expanded foam like structure, water or saline
can be added with rapid mixing above the
phase tranisition temperature to give MLVs.
32
40. The transient change in pH brings about an
increase in surface charge of the lipid bilayer
which induces spontaneous vesiculation .
COCHLEATE METHOD :
LUV’s
Removal of
calcium by
Cylindrical EDTA
rolls(cochleate
cylinders)
Addition of
Ca++ ions
SUV made
from
phosphatidyl 39
choline
41. • In this method lipids are first dissolved in an organic
solution, which is then brought into contact with the aqueous
phase containing materials to be entrapped within the
liposome.
• At the interface between the organic and aqueous media ,the
phospholipids align themselves into a monolayer which form
the basis for half of the bilayer of the liposome.
40
43. Generally the liposome is made up in 2 steps:
1 st the inner leaflet of the bilayer .
Then the outer half.
Aq medium contng
matrl to be entrapped
Methods to prepare the droplets:
1)Double emulsion vesicles Add to immiscible org
sol of lipid
2) Reverse phase evaporation vesicles
3)Sonication methods
Mechanical agitation
42 Microscopic water
droplets
44. In this method, the outer portion of liposome
membrane is created at a second Interface b/w
two phases by emulsification of an organic soln
in water.
w/o Excess aq w/o/w Removal of Unilamellar
emulsion medium emulsion solvent vesicles
43
46. The phospholipids are brought into contact with aq phase via the
detergent,which associate with phospholipid molecules.The
structures formed as a result of this association are MICELLES.
Below CMC,detergent molecules exist in free soln.
As the concentration is increased,micelles are formed.
At three stage model of interaction for detergents with lipid bilayers :
At low concn,detergent equilibrates b/w vesicular lipid and water
phase.
After reaching CMC, membrane tends to be unstable & transforms
into micelles
At stage three, all lipid exists in mixed micelle form.
In all the methods,the basic feature is to remove the detergent from
preformed Mixed vesicles contng phopholipid,whereupon
unilamellar vesicles form spontaneously.
Methods to remove detergents :
Dialysis
Column chromatography
Use of bio-beads
45
47. 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 & outside of liposomes . 46
48. Liposomes with low internal
pH
Solute bearing no charge at
neutral pH
Neutral solute passes easily
through bilayer membrane by
diffusion
Charge aquired by solute
inside liposomes makes 47
them unable to exit
49. pH gradient is created by preparing liposomes with low internal
pH.
Addtn of base to extraliposomal medium.
[Basic compds ( lipophilic (non ionic) at high pH &
hydrophilic(ionic) at low pH)]
Lipophilic (UNPROTONATED) drug diffuse through the bilayer .
At low pH side, the molecules are predominantly protonated .
48
50. The following have beem successfully
encapsulated:
Weak bases such as
Doxorubicin
Adriamycin
Vincristine
Short modified peptides and insulin
49
51. HYDROPHILIC (DOXORUBICIN)
Low entrapment
Leakage
Hydrolytic degradation
LIPOPHILIC (CYCLOSPORINE)
High entrapment
Low leakage
Chemical stability
AMPIPHILIC (VINBLASTIN)
High entrapment
Rapid leakage
BIPHASIC INSOLUBLE
(ALLOPURINOL, 6-
MERCAPTOPURINE)
Poor loading and entrapment
50
52. CHARACTERISATION OF LIPOSOMES
CHARACTERISATION PARAMETERS ANALYTICAL METHOD/INSTRUMENT
1. Vesicle shape and surface morphology Transmission electron microscopy,
Freeze-fracture electron microscopy
2. Mean vesicle size and size distribution Photon correlation spectroscopy, laser
(submicron and micron range) light scattering, gel permeation and gel
exclusion
3. Surface charge Free-flow electrophoresis
4. Electrical surface potential and surface Zetapotential measurements
pH
5. Lamellarity Small angle X-ray scattering, 31 P-NMR,
Freeze-fracture electron microscopy
6. Phase behavior Freeze-fracture electron microscopy,
Differential scanning calorimetery
7. Percent of free drug/ percent capture Minicolumn centrifugation, ion-exchange
chromatography, radiolabelling
8. Drug release Diffusion cell/ dialysis
51
54. CHARACTERISATION PARAMETER ANALYTICAL METHOD/INSTRUMENT
1. Sterility Aerobic or anaerobic cultures
2. Pyrogenicity Limulus Amebocyte Lysate (LAL) test
3. Animal toxicity Monitoring survival rates, histology and
pathology
53
55. Adsorption Endocytosis
Fusion Lipid transfer
54
56. Stability invitro .
Lipid oxidation
Lipid peroxidation
Lipid hydrolysis
Long term & accelerated stability
Stability invivo
Stability after systemic administration.
Stability after oral administration.
55
57. STORAGE CONDITIONS
Liposomes are packed in 1-2 ml sterile vials and stored
at 4 C and room temperature.
The samples stored at 4 C exhibited activity in
transfection showed no aggregation or precipitation.
The samples stored at RT still showed some transfection
activity.
Liposome dispersions are potentially prone to
hydrolytic degradation and leakage.
Hence, it is desirable to freeze dry the suspension to a
powder and store in this dried form.
The powder can be reconstituted to an aqueous
suspension immediately before use.
By doing so SUVs may be converted to MLVs
dispersion upon rehydration.
Addition of a carbohydrate (trehalose) during freeze
drying prevents fusion and leakage of the vesicles.
56
58. Stability of liposomes mainly depend on
structure of lipids and its amount.
Examples:
1)DOXIL: stable for more than 18 months in
liquid state without lyophilisation due to
pegylated nature.
2)AMBISOME: liposomal preparation of
Amphotericine available as lyophilised
cake.After reconstitution not stable for more
than a day.
57
59. Pharmacokinetics of liposomes mainly deals with time
course of absorption, distribution and degradation of
liposomal carriers invivo.
Pharmacokinetic information can be used to interpret
the differences in pharmacological effect of the
liposome entrapped drug and free drug and
subsequently can be exploited for dose regimen.
Liposomes can alter both tissue distribution and rate of
clearance of the drug as they are affected by
pharmacokinetic parameters of the carrier.
Bioavailabilty in case of liposomal carriers can be
defined as the amount of free drug that is able to
escape the carriers and thus available for redistribution
to neighbouring tissue. 58
60. Protection of drug from metabolism and
inactivation in plasma.
Reduced volume of distribution and hence
decrease in non specific localisation.
Higher therapeutic index.
Decrease in amount and type of non specific
toxicity.
Increase in concentration of drug at target site.
59
61. 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 gene delivery.
In immunology.
In cosmetology
60
63. NAME TRADE NAME COMPANY INDICATION
Liposomal Abelcet Enzon Fungal infections
amphotericin B
Liposomal Ambisome Gilead Sciences Fungal and protozoal infections
amphotericin B
Liposomal cytarabine Depocyt Pacira (formerly Malignant lymphomatous meningitis
SkyePharma)
Liposomal DaunoXome Gilead Sciences HIV-related Kaposi’s sarcoma
daunorubicin
Liposomal doxorubicin Myocet Zeneus Combination therapy with cyclophosphamide
in metastatic breast cancer
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 Doxil/Caelyx Ortho Biotech, HIV-related Kaposi’s sarcoma, metastatic
doxorubicin Schering-Plough breast cancer, metastatic
ovarian cancer
Micellular estradiol Estrasorb Novavax Menopausal therapy
62
64. MARKETED DRUG USED TARGET DISEASE COMPANY
PRODUCT
Doxil Doxorubicin Kaposis sarcoma SEQUUS,USA
Amphotec Amphotericin B Fungal infections SEQUUS,USA
leishmaniasis
Fungizone Amphotericin B Fungal infections Bristol squibb
Leishmaniasis netherland
Ventus Prostaglandin –E1 Systemic inflammatory The liposome
disease company USA
Topex Br Terbutaline sulphate asthma Ozone ,USA
Depocyt cytarabine Cancer therapy Skye pharm,USA
Novasome Small pox vaccine Small pox Novavax,USA
Avian retrovirus Killed avian retro virus Chicken pox Vineland lab,USA
vaccine
Vincasome vincristine Solid tumours Nextar, USA
63
65. Several methods of preparing liposomes were
identified, which could influence the particle
structure, degree of drug entrapment and leakage of the
liposomes.
It was also identified that there are improved pharmacokinetic
properties with liposomal drugs compared to the free drugs.
Furthermore, liposomes are tools for drug targeting in certain
biomedical situations (e.g., cancer) and for reducing the
incidence of dose related drug toxicity.
Instability of the preparations is a problem, which is yet to
be overcome before full commercialisation of the process
can be realised.
64
66. Target and Controlled Drug delivery – Novel Carrier Systems by
S.P. Vyas and R.K. Khar
Controlled and Novel Drug Delivery Systems by Sanjay K. Jain
and N.K.Jain .
www.pharmaxchange.info
http://www.pharmainfo.net/reviews/liposome-versatile-
platform-targeted-delivery-drugs
“Liposomes preparation methods” a review by Mohammad riaz
in Pakistan journal of pharmaceutical sciences
“A review on liposomes” by venkateshwarlu in Research
Journal of Pharmaceutical, Biological and Chemical Sciences
“Stealth liposomes” a review by Kataria Sahil in IJRAP
Lamella: A Lamella is a flat plate like structure that appears during the formation of liposomes. The Phospholipidbilayer first exists as a lamella before getting convered into spheres.
French pressure cell liposomes: Extrusion of preformed large liposomes in a french press under high pressure--- Uni or oligolammellarliposomes Advantages: More stable & less leakage of contents compared to sonicatedliposomes .
BIPHASIC INSOLUBLE Poor loading and entrapment
PRESENTED BY:PRIYANKA ODELADepartment of pharmaceuticsM –PHARM 1st yrRoll.no.5GPRCP.