liposome and nanotechnology
TRANSCRIPT
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
