liposome and nanotechnology

SEMINAR ON

LIPOSOMES

SEMINAR ON ……..

List of contents

o Introduction:

o Advantages with use of liposomes as drug delivery

system.

o Classification

o Manufacturing of liposomes

o Liposome characterization and control

o Stability consideration for liposomal formulations

o Regulatory science of liposome drug products

o Drug release from liposomes

o Applications

o Recent innovations

o Approved liposome products

o References

INTRODUCTIONo The preparation of liposomes, with

entrapped solutes, was demonstrated for the first time in 1965 by Prof. A.D. Bangham of the United Kingdom.

Definitiono “Liposomes are microscopic spheres made from

fatty materials, predominantly phospholipids.

o “made up of one or more concentric lipid bilayers, and range in size from 50 nanometers to several micrometers in diameter”

Advantages with liposomes

o Suitable for delivery of hydrophobic, hydrophilic and amphipatic drugs and agents

o Chemically and physically well characterized entities

o Biocompatible

o Suitable for controlled release

o Suitable to give localized action in particular tissues.

o Suitable to administer via various routes

Classification

o Classification based on size of liposomes

o Classification based on method of preparation

o Classification based on composition and in vivo application

Classification based on sizeSmall unilamellar vesiclesMedium sized unilamellar vesiclesLarge unilamellar vesiclesGiant unilamellar vesiclesUnilamellar vesiclesOligolamellar vesiclesMultilamellar large vesiclesMultivesicular vesicles

Classification based on method of preparation

o Vesicles prepared by extrusion method.o Vesicles prepared by French press.o Vesicles prepared by fusion.o Vesicles prepared by reverse phase

evaporation.o Frozen and thawed MLV.o Dehydration and rehydration vesicles.o Stable plurilamellar vesicles.

Classification based on specific properties

o Conventional Liposomes

Long circulating liposomes (Stealth Technology)

o PEG coating o Low permeability liquid matrix and

internal aqueous buffer system

Targeted liposomeso Target specific ligands, such as

antibodies, immunoglobulins, lectins and oligosaccharides attached to the surface

Cationic Liposomeso Cationic lipid component interact with

negatively- charged DNAo Results into Lipid –DNA Complexes

Temperature sensitive liposome

PH sensitive Liposomes

MANUFACTURING OF

LIPOSOMES

Materials used in preparation of liposomes

o Phospholipidso Synthetic Phospholipidso Glycerolipids o Sphingolipidso Glycosphingolipidso Steroidso Polymeric materialo Charge-inducing lipids

Structure of phospholipids

Issues to consider when selecting lipids.

o Phase transition temperatureo Stabilityo Chargeo Lipid mixtureso Cholesterolo Source

Preparation of Liposomes

Mechanism of Vesicle Formation

o The budding theoryo The bilayer phospholipids theory

The budding theoryo Stress induced hydration of phospholipidso Organization in to lamellar arrayso Results in to budding of lipid bilayer leading to down

sizing

SUV OLV

The bilayer phospholipids theory

o Liposomes are formed when thin lipid films are hydrated

o The hydrated lipid sheets detach during agitation and self-close to form large, multilamellar vesicles (LMV)

Method of

Liposome Preparation

Conventional liposome preparation methods

PhospholipidsCholesterol Antioxidant

Lipid component compounding Lipid solvent

Pyrogen Ultrafilteryes

No

Filter

Solvent removal

Drug ,Salt Antioxidant Buffer WFI

Filter

HydrationSolvent recovery

Extrusion Down sizing

Free drug removal

Prefilter

Sterile filter

Vial filling

Free drug recovery

Aseptic processingLyophollization Seal / package

Method for preparation of (SUV)

o Sonicationo High shear fragmentationo Solvent injection method

o Injection of water immiscible solvent.o Ether infusion.o Fluorocarbon injection.

o Injection of water miscible solvent.o Ethanol injectiono Modified ethanol injection method

High shear fragmentation

Aqueous samples

Piston

Cell body

Rubber-O-ring

Closure plug

Pressure relief valve

OutletFig. French pressure cell

Solvent injection method.

Vacuumpump

Mix

Gasket

Ether/lipidsolution

Infusion pump

Aqueousphase

Mechanical drive

TemperatureControlledbath

Large and Intermediate sized unilamellar vesicles.

o Methods used to prepare LUV and IUVo Detergent dialysiso Water in oil emulsion techniqueo Freeze thaw cyclingo Slow swelling in non electrolyteso Dehydration followed by rehydrationo Dilution or dialysis of lipids in the presence

of chaotropic ions.

Reverse phase evaporation technique.

Lipid in solvent solution

Two-phase system Water in oil emulsion

Solvent removalGel formationREV liposomes

High pressure extrusion.

Methods for controlling liposome size

o Fractionationo Centrifugationo Size exclusion chromatography

o Homogenization

o Capillary pore membrane extrusion

o Ceramic extrusion

Liposome characterization and control

Liposomes

Size Number of lamellae

Charge Stability

Preparation Raw materials

Protection

Sizing method

Hydration methods

Degree of saturation

Head group

Presence of sterols

Protecting

agents

Characterized by

Determined by

Classified by

Physical characterization parameters

o Mean size and size distribution

o Number of lamellae

o Osmotic behavior and entrapped volume

o Internal distribution of drug

o Structural and motional behavior of lipids

o Electrical surface potential & Surface PH

o Stabilization aspect for physical instability of liposomes

o Chemical stability

o Biological stability of liposomes

Stability consideration

Regulatory aspectso Safety concerns: liposome

formulationo Lipid toxicity (RBC lysis)o Presence of protein and lipoprotein for

natural lipidso Residual solvento Overload of RES o Particle size

o (tail above 1 um) - Blockage of capillarieso Size affects RES uptake and tissue targeting

o Stability: shelf-live and in vivoo Dose dumping (via protein binding)o Sterility

Drug release from liposomes

o The lipid bilayer of the liposome can fuse with other bilayers (e.g. cell membrane) thus delivering the liposome contents.

Liposome Performance – In Vitro Release and Stability

o In vitro drug release from liposomal systems was determined using dialysis sacks.

o Release test for a targeted liposome would need to show that liposome is stable until uptake at the site.

Factors affecting release of drug

o Solventso pHo Temperatureo Agitationo Enzymeso Cell cultureo Sink conditionso Volumeo Sampling interval

Applications

o Liposomes as Protein Carriers in Immunology

o Oral Drug Delivery

o Site Specific Delivery

o Sustained or Controlled Delivery

o Gene Therapeutics

Applications

Innovations in vesicular drug delivery systems

o Provesicles in drug delivery systems

o Provesicles in drug delivery systems

o Proliposomes :-o Dry granular liposomeso Mixed micellar proliposomeso Protransferosomes

Characterization of provesicular system

o Morphology o Angle of reposeo Size and size distributiono Rate of hydration o Entrapment efficiencyo Degree of deformability and

permeability measuremento In vitro release rateo In vivo fate and pharmacokinetic

Lipopolyplexes

o A combination of DNA, polymers and liposomes

o This method has resulted in better gene transfer and lower toxicity as compare to cationic liposomes

Transferosomes

o Modified liposomes developed to increase the transdermal permeation of drug

o Deformability is achieved by using surface active agent in proper ratio

o Concentration of surfactant is very crucial

Ethosomes

o Composed of phospholipids & alcohol ( ethanol or IPA)

o Sometimes polyols or glycols in relatively high concentration & water

o Better membrane permeability

o Discomes

o Virosomes

o Emulsomes

Cochleateso Cochleates are cigar-like microstructures

o Consist of a series of lipid bilayers which are formed as a result of the condensation of small unilamellar negatively charged liposomes.

Depofoam technology

o Depofoam particles include hundred of bilayer enclosed aqueous compound.

o Formed by first emulsifying a mixture of an aq phase containing the compound to be encapsulated & an organic phase containing lipid.

Niosomes

o Nonionic surfactant vesicles(NSV)

o Niosomes are formed from the self assembly of non-ionic amphiphiles in aqueous media resulting in closed bilayer.

Preparation of Liposomes by dry film method

o Lipids and drug dissolved in CHCl3

and evaporated to form thin film

o Film is hydrated with buffer solution

o Sonicated to form large unilamellar vesicles

Preparation of Liposomes by dry film method

Lipid + drug + CHCl3

Rotary evaporation

Sonication

Thin film

LUV

Approved liposome products marketed in US

Doxil Daunorubicin Alza Corporation

Kopasi sarcoma

Daunoxome Daunorubicin Gilead sciences

,,

Ambisome Amphotericin B ,, Serious fungal infection

Approved lipid complex products

Ambelcet Amphotericin B Alza corporation Amphotec Amphotericin B Elan corporation