Targeting methods introduction preparation and evaluation: NanoParticles & Liposomes: Types, preparation and evaluation

(M.PHARM. Pharmaceutics) 2nd Semester
MOLECULARPHARMACEUTICS –MPH201T

1. (M.PHARM. Pharmaceutics)2
nd
Semester
MOLECULAR PHARMACEUTICS –MPH201T
Targeting Methods:
Introduction preparation and evaluation,
NanoParticles & Liposomes:
Types, preparation and evaluation
By
SURYAKANT VERMA
Assistant Professor,
Department ofPharmaceutics,

2. CONTENTS
1. Targetingmethods
•Introduction
2. Nanoparticles
•Types
•Preparation
•Evaluation
3. Liposomes
•Preparation
•Evaluation
•Applications

3. TARGETINGMETHODS:-
Aspecialformofdrugdeliverysystemwherethepharmacologically
activeagentormedicamentisselectivelytargetedordeliveredonly
toitssiteofactionorabsorptionandnottothenon-targetorgansor
tissuesorcells.
Targeteddrugdeliveryimpliesforselectiveandeffective
localizationofpharmacologicallyactivemoietyatpreidentified
(preselected)targetintherapeuticconcentration,whilerestricting
itsaccesstonon-targetnormalcellularlinings,thusminimizing
toxiceffectsandmaximizingtherapeuticindex.
INTRODUCTION

4. •Targetingofdrugsalsohelpustobypassfirstpassmetabolismsoa
drugcanbeadministeredinaformsuchthatitreachesthereceptor
sitesinsufficientconcentrationwithoutdisturbinginextraneous
tissuecells.
•Targeteddrugdeliverysystemshouldbe-biochemicallyinert(non-
toxic),non-immunogenic.
•Bothphysicallyandchemicallystableinvivoandinvitro.
•Restrictdrugdistributiontotargetcellsortissuesororgansand
shouldhaveuniformcapillarydistribution.
•Controllableandpredictablerateofdrugrelease.
•Shouldhavetherapeuticamountofdrugrelease.
•Shouldhaveminimaldrugleakageduringtransit.
•Carriersusedshouldbebio-degradableorreadilyeliminatedfrom
thebodywithoutanyproblem.
•Thepreparationofthedeliverysystemshouldbeeasyorreasonably
simple,reproductiveandcosteffective.
CHARACTERISTICS

5. ADVANTAGES
DISADVANTAGES
•Rapidclearanceoftargetedsystems.
•Immunereactionsagainstintravenousadministeredcarrier
systems.
•Insufficientlocalizationoftargetedsystemsintotumourcells.
•Diffusionandredistributionofreleaseddrugs.
•Drugadministrationprotocolsmaybesimplified.
•Drugquantitymaybegreatlyreducedaswellasthecostof
therapy.
•Drugconcentrationintherequiredsitescanbesharply
increasedwithoutnegativeeffectsonnon-targetcompartments.

6. 1)Passive Targeting
2)Active Targeting
3)Inverse Targeting
4)LigandMediated Targeting
5)Physical Targeting
6)Dual Targeting
7)Double Targeting
STRATEGIES OF DRUG TARGETING

7. 1)PassiveTargeting:-
•Drugdeliverysystemswhicharetargetedtosystemiccirculationare
characterizedasPassivedeliverysystems.
•Inthistechniquedrugtargetingoccursbecauseofthebody’snaturalresponse
tophysicochemicalcharacteristicsofthedrugordrugcarriersystem.
2)ActiveTargeting:-
Inthisapproachcarriersystembearingdrugreachestospecificsiteonthe
basisofmodificationmadeonitssurfaceratherthannaturaluptakebyRES.
•Surfacemodificationtechniqueincludecoatingofsurfacewitheithera
bioadhesive,nonionicsurfactantorspecificcellortissueantibodies(i.e.
monoclonalantibodies)orbyalbuminprotein.
Thereare3TypesofActiveTargeting
1.Firstordertargeting(organcompartmentalization).
2.Secondordertargeting(cellulartargeting).
3.Thirdordertargeting(intracellulartargeting).
STRATEGIES OF DRUG TARGETING

8. STRATEGIES OF DRUG TARGETING
3)InverseTargeting:-
•Inthistypeoftargetingattemptsaremadetoavoidpassiveuptake
ofcolloidalcarrierbyRES(ReticuloEndothelialSystems)and
hencetheprocessisreferredtoasinversetargeting.
•Toachieveinversetargeting,RESnormalfunctionissuppressedby
preinjectinglargeamountofblankcolloidalcarriersor
macromoleculeslikedextransulphate
•ThisapproachleadstosaturationofRESandsuppressionof
defencemechanism.
•Thistypeoftargetingisaeffectiveapproachtotargetdrug(s)to
non-RESorgans.
4)LigandMediatedTargeting:-
Achievedusingspecificmechanismssuchasreceptordependent
uptakeofnaturalLDLparticlesandsyntheticlipidmicroemulsions
ofpartiallyreconstitutedLDLparticlescoatedwiththeapoproteins.

9. STRATEGIES OF DRUG TARGETING
5)PhysicalTargeting:-
•InthistypeoftargetingsomecharacteristicsofenvironmentchangeslikepH,
temperature,lightintensity,electricfield,ionicstrengthsmallandevenspecific
stimulilikeglucoseconcentrationareusedtolocalizethedrugcarrierto
predeterminedsite.
•Thisapproachwasfoundexceptionalfortumourtargetingaswellascytosolic
deliveryofentrappeddrugorgeneticmaterial.
6)DualTargeting:-
•Inthistargetingapproachcarriermoleculeitselfhavetheirowntherapeutic
activityandthusincreasethetherapeuticeffectofdrug.
•Forexample,acarriermoleculehavingitsownantiviralactivitycanbeloaded
withantiviraldrugandthenetsynergisticeffectofdrugconjugatewasobserved.
7)DoubleTargeting:-
•Temporalandspatialmethodologiesarecombinedtotargetacarriersystem,then
targetingmaybecalleddoubletargeting.
•Spatialplacementrelatestotargetingdrugstospecificorgans,tissues,cellsor
evensubcellularcompartment.whereastemporaldeliveryreferstocontrollingthe
rateofdrugdeliverytotargetsite.

10. •Targeteddrugdeliverycanbeachievedbyusingcarriersystem.
•Carrierisoneofthespecialmoleculeorsystemessentially
requiredforeffectivetransportationofloadeddruguptothepre
selectedsites.
•Theyareengineeredvectors,whichretaindruginsideoronto
themeitherviaencapsulationand/orviaspacermoietyand
transportordeliveritintovicinityoftargetcell.
Pharmaceuticalcarriers:
Polymers
Microcapsules
Microparticles
Lipoproteins
Liposomes
Micelles
Nanoparticles
CARRIER OR MARKERS

11. NANOPARTICLES

12. INTRODUCTION
TheprefixnanocomesfromtheancientGreekvavocthrough
theLatinnanusmeaningverysmall.
Nanoparticlesaredefinedasparticulatedispersionsorsolid
particleswithasizeintherangeof10-1000nm.
Thedrugdissolved,entrapped,encapsulatedorattachedtoa
nanoparticlematrix.
Thetermnanoparticleisa
combinednameforboth
nanospheres and
nanocapsules.
Drugisconfinedtoacavitysurroundedbyauniquepolymer
membranecallednanocapsules,whilenanospheresare
matrixsystemsinwhichthedrugisphysicallyanduniformly
dispersed.

13. NANOPARTICLES
NANOCAPSULES -
Thenanocapsulesare
systeminwhichthe
drugisconfinedtoa
cavitysurroundedby
auniquepolymer
membrane.
NANOSPHERES-
Thenanospheresare
matrixsystemsin
whichthedrugis
physically and
uniformlydispersed.

14. IDEALPROPERTIESOFNANOPARTICLES
NECESSARYFORDRUGDELIVERY
Stableinblood
Nontoxic
Non-thrombogenic
Non-
inflammatory
Non-immunogenic
Biodegradable

15. ADVANTAGES OFNANOPARTICLES
Fairlyeasypreparation
Good protection
of the
encapsulateddrug
Increased
therapeutic
efficacy
Targetedanddrug
delivery
Retentionofdrug
attheactivesite
Increased
bioavailability
Goodcontroloversize
andsizedistribution
Longerclearance
time
Dose
proportionality

16. ADVANTAGES OF NANOPARTICLES
•Nanoparticleshavemanysignificantadvantageoverconventionalandtraditional
drugdeliverysystem.
•Nanoparticlesarecontrolandsustainreleaseformatthesiteoflocalization,
theyalterorgandistributionofdrugcompound.Theyenhancedrugcirculationin
blood,bioavailability,therapeuticefficacyandreducesideeffects.
•Nanoparticlescanbeadministerbyvariousroutesincludingoral,nasal,
parenteral,intra-ocularetc.
•Inthetinyareasofbodynanoparticlesshowsbetterdrugdeliveryascompareto
otherdosageformandtargettoaparticularcelltypeorreceptor.
•Nanoparticleenhancetheaqueoussolubilityofpoorlysolubledrug,which
improvesbioavailabilityofdrug.
•Asatargeteddrugcarriernanoparticlesreducedrugtoxicityandenhance
efficientdrugdistribution.
•Usefultodiagnosevariousdiseases.
•Enhancedstabilityofingredients.

17. DISADVANTAGES OFNANOPARTICLES
Limitedtargeting
abilities
Discontinuation of
therapyisnotpossible
Toxicity
Disturbanceof
Autonomic
imbalance
Cytotoxicity

18. NANOMEDICINES FORDRUGDELIVERY

19. S.NO
TYPESOF
NANOPARTICLE
MATERIALSUED APPLICATION
1
Nanosuspensions
and Nanocrystals
Drugpowderis
disperse din
surfactantsolution
Stable system for
controlleddeliveryof
poorlysolubledrug
2 SolidlipidNanoparticles
Meltedlipid
dispersedin
Aqueoussurfactant
Leasttoxicandmore
stable
Colloidalcarriersystems as
alternativematerialsTo
polymers
3
PolymericnanoparticlesBiodegradablepolymer
Controlledandtargeted
drugdelivery
4 Polymericmicelles
Amphiphilic
blockco
polymers
Controlledandsystemic
Delivery of water insoluble
Drugs
5 MagneticNanoparticles
MagnetiteFe2O3,Meghe
Mitecoatedwithdextran
Drugtargeting
diagnostics
toinmedicine
6 CarbonNanotubes Metals,semiconductorsGene andDNAdelivery

20. ROUTES

21. POLYMERUSEDINPREPARTION
Natural
Hydrophilic
PROTEINS
POLYSACCHARIDES
Synthetic
Hydrophobic
PRE-
POLYMERIZED
POLYMERIZEDIN
PROCESS

22. NATURALHYDROPHILICPOLYMER
PROTEINS POLYSACCHARIDES
Gelatin Alginates
Albumin Dextran
Lectins Chitosan
Legumin Agarose
Vicilin Pullulan

23. SYNTHETICHYDROPHOBICPOLYMER
PRE-POLYMERIZED POLYMERIZED IN PROCESS
Poly (e-caprolactone) (PECL)
Poly(isobutylcyanoacrylates)
(PICA)
Poly(lactic acid) (PLA)Poly(butylcyanoacrylates) (PBCA)
Poly(actide -co-glycolide (PLGA)Polyhexylcyanoacrylate (PHCA)
Polystyrene
Poly methyl
(methacrylate)(PMMA)

24. TECHNIQUESOFPREPARATION
IONIC
GELATION
POLYMERIZATION
PREFOEMED
POLYMERS

25. METHODSOFPREPARATIONOFNANOPARTICLES
BYDISPERSION OFPREFORMED POLYMER

26. METHODFORPREPARATIONOFNANOPRATICLES
BYPOLYMERIZATION OFMONOMERS
EMULSION
POLYMERIZATION
MINI-EMULSION
POLYMRIZATION
MICRO-EMULSION
POLYMRIZATION
INTERFACIACL
POLYMERIZATION
CONTROLLED/
LIVING
RADICAL
POLYMERIZATION

28. PREPARATION TECHNIQUES
SolventEvaporation:-
•Solventevaporationmethodfirstdevelopedforpreparation
ofnanoparticles.
•Inthismethodfirstlynanoemulsionformulationprepared.
•Polymerdissolvedinorganicsolvent(dichloromethane,
chloroformorethylacetate).
•Drugisdispersedinthissolution.
•Thenthismixutureemulsifiedinanaqueousphase
containingsurfactant(polysorbates,poloxamers,polyvinyl
alcohol,).
•Thismakeanoilinwateremulsionbyusingmechanical
stirring,sonication,ormicrofluidization(high-pressure
homogenizationthroughnarrowchannels).

29. Representation of the solvent –evaporation technique.

30. DoubleEmulsificationMethod:-
•Emulsificationandevaporationmethodhave
limitationofpoor entrapmentOFhydrophilic
drugs,hencedoubleemulsificationtechniqueisused.
•Firstlyw/oemulsionpreparedbyadditionofaqueous
drugsolutiontoorganicpolymersolutionwith
continuousstirring.
•Thispreparedemulsionanotheraqueousphasewith
vigorousstirring,resultantw/o/wemulsionprepared,
thenorganicsolventremovedbyhighcentrifugation.
PREPARATION TECHNIQUES

31. Emulsions-DiffusionMethod:-
•ThismethodpatentbyLerouxetalanditismodifiedformof
saltingoutmethod.
•Polymerdissolvedinwater-misciblesolvent(propylenecarbonate,
benzylalcohol),thissolutionsaturatedwithwater.
•Polymer-watersaturatedsolventphaseisemulsifiedinanaqueous
solutioncontainingstabilizer.Thensolventremovedbyevaporation
orfiltration.
PREPARATION TECHNIQUES

32. Nano precipitationmethod:-
•Inthismethodprecipitationofpolymeranddrugobtainedfrom
organicsolventandtheorganicsolventdiffusedintothe
aqueousmediumwithorwithoutpresenceofsurfactant.
•Firstlydrugwasdissolvedinwater,andthencosolvent(acetone
usedformakeinnerphasemorehomogeneous)wasaddedinto
thissolution.
•Thenanothersolutionofpolymer(ethylcellulose,eudragit)and
propyleneglycolwithchloroformprepared,andthissolution
wasdispersedtothedrugsolution.
•Thisdispersionwasslowlyaddedto10mlof70%aqueous
ethanolsolution.
PREPARATION TECHNIQUES

33. •After5minutesofmixing,theorganicsolventswere
removedbyevaporationat35°undernormal
pressure,nanoparticleswereseparatedbyusing
coolingcentrifuge(10000rpmfor20min),
supernatantwereremovedandnanoparticleswashed
withwateranddriedatroomtemperatureina
desicator.
PREPARATION TECHNIQUES

34. Coacervationmethod:-
•Drugandproteinsolution(2%w/v)incubatedforonehourat
roomtemperatureandpHadjustedto5.5byusing1MHCl.
•Inthissolutionethanolwasaddedin2:1ratio(v/v)inacontrole
rate1ml/min.
•Resultantcoacervatehardenedwith25%glutaraldehyde(1.56
μg/mgofprotein)for2hourswhichallowcross-linkingof
protein.
•RotaryVacuum evaporationatreducedpressure
organicsolventswereremovedthennanoparticlewerecollected
andpurifiedbycentrifugationatfourdegreecentigrade.
•Pelletsofnanoparticleswerethensuspendedinphosphatebuffer
(pH7.4;0.1M)andlyophilizedwithmannitol.
PREPARATION TECHNIQUES

35. SaltingOutMethod:-
•Saltingoutmethodisveryclosetosolvent
diffusionmethod.
•Thistechniqueisbasedontheseparationofwater-
misciblesolventfromaqueoussolutionbysalting
outeffect.
•Inthismethodtoxicsolventsarenotused.
•Generallyacetoneisusedbecauseitistotally
misciblewithwaterandeasilyremoved.
PREPARATION TECHNIQUES

36. •Polymeranddrugdissolvedinasolventwhichemulsified
intoaaqueoussolutioncontainingsaltingoutagent
(electrolytes,suchasmagnesiumchlorideandcalcium
chloride,ornonelectrolytessuchassucrose).
PREPARATION TECHNIQUES

37. DIALYSIS:-
Dialysisisaneffectivemethodfor
preparationofnanoparticles.
Inthismethodfirstlypolymer(such
asPoly(benzyl-glutamate)-b-
poly(ethyleneoxide),Poly(lactide)
anddrugdissolvedinaorganic
solvent.
Thissolutionaddedtoadialysis
tubeanddialysisperformed.
PREPARATIONTECHNIQUES

38. EVALUATIONPARAMETER OFNANOPARTICLES
1)YIELDOFNANOPARTICLES:-
PrecentageYield=Amountofparticle(100)
Amountofdrug+polymer
2)DRUGCONTENT/SURFACE
ENTRAPMENT/ DRUG ENTRAPMENT:-
Precentagedrugentrapment=W-w(100)
W
3)PARTICLESIZE:-Particlesizeanditsdistributionisimportant
characteristicsinnanoparticlesastheyplaysmajorroleindistribution,
pharmacologicalactivity,toxicityandtargetingtospecificsites.
Advancedmethodstodeterminetheparticlesizeofnanoparticlesisby
photon-correlationspectroscopyordynamiclightscattering,scanning
electronmicroscopy

39. 4)PARTICLESHAPE:-Particleshapeofthenanosuspensionsis
determinedbyscanningelectronmicroscopy(SEM).Inordertoformthe
solidparticlesthesenanosuspensionsweresubjectedtolyophilisation.
5)ZETAPOTENTIAL:-Zetapotentialisthepotentialdifference
existingbetweenthesurfaceofasolidparticleimmersedinaconducting
liquidandthebulkoftheliquid.Thesurfacechargeofthenanoparticlesis
usuallymeasuredbyzetapotential.
4)DIFFERENTIALSCANNINGCALORIMERTY (DSC):-
Itisusedtodeterminethenatureofcrystallinitywithinnanoparticles
throughthemeasurementofglassandmeltingpointtemperturesandtheir
associatedenthalpies.
5)ATOMICFORCEMICROSCOPY (AFM):-Itoffersaultra-
highresolutioninparticlesizemeasurementandisbasedonaphysical
scanningofsampleatsub-micronlevelusingaprobetipofatomicscale.
AFMprovidesthemostaccuratedescriptionofsizeandsizedistribution
andrequiresnommathemicaltreatment.

40. DRUGLOADING
INCORPORATIONMETHOD
INCUBATIONMETHOD
INCORPORATION METHOD-Incorporatingatthetimeofnanoparticle
production
INCUBATIONMETHOD-Adsorbingthedrugaftertheformationof
nanoparticlesbyincubatingthecarrierwiththeconcentrateddrug
solution.
Bothmethodsresultin:
Asolidsolutionofthedruginthepolymers
Soliddispersionoftheduginthepolymer.
Surfaceadsorptionofthedrug.
Chemicalbondingofthedruginthepolymer.

41. DRUGRELEASEANDRELEASEKINETIC
Thereleaseofdrugfrom
theparticulatesystem
dependsuponthree
differentmechanism:
Releasefromthe
surfaceofparticles.
Diffusionthrough
theswollenrubbery
matrix.
Releaseduetoerosion.

42. EVALUATIONFORRELEASEOFDRUG
Variousmethodswhichcanbeusedtostudytheinvitro
releaseofthedrugfromnanoparticlesare:
1.Side-by-sidediffusioncellswith artificalorbiological
membranes
2.Dialysisbag diffusiontechnique
3.Reversedialysisbagtechnique
4.Agitationfollowedbyultracentrifugation/centrifugation
5.Ultra-filtrationorcentrifugalultra-filtrationtechniques

43. INVITRO DRUGRELEASESTUDIES
USPType2
RPM50
Immersedin900
mlofphosphate
buffersolution
Temperature37+
0.02degree
Celsius
Withdrawn 5ml
solutionfromthe
medium
Specifictime
periods
•DISSOLUTION:-
Samevol.of
dissolution
mediumreplaced
intheflask
Maintain the
constantvolume
Withdrawn
samples analyzed
using UV
Spectrophotomete
rer

44. •STABILITYOFNANOPARTICLES:-
•Nanoparticles
detemination
•Storing
optimized
formulation
4degreeCelsius+ 1
degree Celsius & 30
dergreecelsius +2
dergreecelsius
0,1,2&3month
time period
•Sample
analyzed
•Stability
chamberfor90
days
•Anychangesin
physical
appearance
Their drug
content,drug
releaserate

45. APPLICATIONS
USEDINTARGETEDDRUGDELIVERYTOBRAINTHERAPY
USEDINTARGETINGOFNANOPRATICLES
TO EPITHELIAL CELLS IN THE GI TRACT
USINGLIGANDS
USED IN BIO
DECTECTIONOF
PATHOGENS
STEMCELL
THERAPY
NANOPARTICLES
FOR GENE
DELIVERY
CANCERTHERAPY

46. TYPESOFNANOPARTICLES
Nanoparticlescanbeclassifiedintodifferenttypesaccordingto
thesize,morphology,physicalandchemicalproperties.Someof
themare;
1.Carbon-based nanoparticles
2.Ceramic nanoparticles
3.Metalnanoparticles
4.Semiconductornanoparticles
5.Polymeric nanoparticles
6.Lipid-based nanoparticles

47. 1.Carbon-basednanoparticles:Itincludestwomainmaterials:
a.Carbonnanotubes(CNTs).
b.Fullerenes.
CNTsarenothingbutgraphenesheetsrolledintoatube.Thesematerialsaremainlyusedfor
thestructuralreinforcementastheyare100times.
Whereas;Fullerenesaretheallotropesofcarbonhavingastructureofhollowcageofsixtyor
morecarbonatoms.ThestructureofC-60isalsocalledBuckminsterfullerene.
2.CeramicNanoparticles
•Ceramicnanoparticlesareinorganicsolidsmadeupofoxides,carbides,carbonatesand
phosphates.
•Thesenanoparticleshavehighheatresistanceandchemicalinertness.
•Theyhaveapplicationsinphotocatalysis,photodegradationofdyes,drugdelivery,and
imaging.
3.MetalNanoparticles
•Metalnanoparticlesarepreparedfrommetalprecursors.
•Thesenanoparticlescanbesynthesizedbychemical,electrochemical,orphotochemical
methods.
•Thesenanoparticleshaveapplicationsindetectionandimagingofbiomoleculesandin
environmentalandbioanalyticalapplications.
TYPESOFNANOPARTICLES

48. TYPES OF NANOPARTICLES
4.SemiconductorNanoparticles
•Semiconductornanoparticleshavepropertieslikethoseofmetalsandnon-metals.
•Theseparticleshavewidebandgaps,whichontuningshowsdifferentproperties.
•Theyareusedinphotocatalysis,electronicsdevices,photo-opticsandwatersplitting
applications.
•SomeexamplesareGan,Gap,Inpetc.fromgroupIII.
5.PolymericNanoparticles
•Polymericnanoparticlesareorganicbasednanoparticles.
•Dependinguponthemethodofpreparation,thesehavestructuresshapedlike
nanocapsularornanospheres.Ananosphereparticlehasamatrix-likestructurewhereasthe
nanocapsularparticlehascore-shellmorphology.
6.Lipid-BasedNanoparticles
•Lipidnanoparticlesaregenerallysphericalinshapewithadiameterrangingfrom10to
100nm.
•Itconsistsofasolidcoremadeoflipidandamatrixcontainingsolublelipophilic
molecules.
•Theexternalcoreofthesenanoparticlesisstabilizedbysurfactantsandemulsifiers.

49. Liposomes

50. Liposomesareconcentricbilayeredvesiclesin
whichanaqueouscoreisentirelyenclosedby
amembranouslipidbilayermainlycomposed
ofnaturalorsyntheticphospholipids.
LIPOSOMES

51. •Liposomesareextensivelyusedascarriersfor
numerousmoleculesincosmeticandpharmaceutical
industries.Additionally,foodandfarmingindustries
haveextensivelystudiedtheuseofliposome
encapsulationtogrowdeliverysystemsthatcanentrap
unstablecompounds(forexample,antimicrobials,
antioxidants,flavorsandbioactiveelements)andshield
theirfunctionality.
•Thesizeofaliposomerangesfromsome20nmupto
severalmicrometers.
LIPOSOMES

52. Basicstructure ofliposome
•ALamellaisaflatplate
likestructurethat
appearsduringthe
formationofliposomes.
•The phospholipids
bilayerfirstexistsasa
lamellabeforegetting
convertedintospheres.
•Severallamellaof
phospholipidsbilayers
arestackedoneontop
oftheotherduring
formationofliposomes
toformamultilamellar
structure.

53. •Providesselectivepassivetargetingtotumor
tissues.
•Increasedefficacyandtherapeuticindex.
•Increasedstabilityofencapsulateddrug.
•Reductionintoxicityoftheencapsulatedagent.
•Improvedpharmacokineticeffects.
•Siteavoidanceeffect(avoidsnon-targettissues).
Liposomesarenon-toxic,flexible,biocompatible,
completelybiodegradable,andnonimmunogenic
forsystemicandnon-systemicadministrations.
ADVANTAGESOFLIPOSOMES

54. •Physical/chemicalstability.
•Veryhighproductioncost.
•Drug leakage/entrapment/drugfusion.
•Sterilization.
•Shortbiologicalactivity/t½.
•Oxidationofbilayerphospholipids.
•Overcomingresistance.
•Repeatedivadministrationproblems.
DISADVANTAGES

55. PREPARATION OFLIPOSOMES
General methods of preparation
All the methods of preparing the liposomesinvolve four
basic stages:
1.Drying down lipids from organic solvent.
2.Dispersing the lipid in aqueous media.
3.Purifying the resultant liposome.
4.Analyzing the final product.
Methodofliposomepreparationanddrugloading
Thefollowingmethodsareusedforthepreparationof
liposome:
1. Passive loading techniques
2. Active loading technique.

56. PREPARATION OFLIPOSOMES
Passive loading techniques include three different methods:
1. Mechanical dispersion method.
2. Solvent dispersion method.
3. Detergent removal method (removal of nonencapsulatedmaterial)
1. Mechanical dispersion method
The following are types of mechanical dispersion methods:
1.1. Sonication.
1.2. French pressure cell: extrusion.
1.3. Freeze-thawed liposomes.
1.4. Lipid film hydration by hand shaking, non-hand. shaking or freeze drying.
1.5. Micro-emulsification.
1.6. Membrane extrusion.
1.7. Dried reconstituted vesicle.

57. PREPARATION OFLIPOSOMES
2. Solvent dispersion method:-
This methods includes:
2.1Ethanolinjection.
2.2Etherinjection.
2.3Doubleemulsionvesicles.
2.4Stableplurilamellar.
2.5Vesicles.
2.6Reversephaseevaporationvesicles.
3. Detergent removal method (removal of nonencapsulatedmaterial):-
This methods includes detergent(Cholate,Alkylglycoside,TritonX-100) removal
from mixed micelles by:
3.1Dialysis.
3.2Column chromatography.
3.3Dilution.
3.4Reconstituted sendaivirus enveloped vesicles.

58. Evaluationofliposomes
Physicalproperties
1.Particlesize:Bothparticlesizeandparticlesizedistributionof
liposomesinfluencetheirphysicalstability.Thesecanbedetermined
bythefollowingmethod.
A.Laserlightscattering.
B.Transmissionelectronmicroscopy.
2.Surfacecharge:Thistechniquecanbeusedfordeterminingthe
heterogeneityofchargesintheliposomesuspensionaswellasto
detectanyimpuritiessuchasfattyacids.
1.Thepositive,negativeorneutralchargeonthesurfaceofthe
liposomesisduetothecompositionoftheheadgroups.
2.Thesurfacechargeofliposomesgovernsthekineticandextent
ofdistributioninvivo,aswellasinteractionwiththetargetcells.
3.Themethodinvolvedinthemeasurementofsurfacechargeis
basedonfree-flowelectrophoresisofMLVs.

59. 3.Percentdrugencapsulated
•Quantityofdrugentrappedintheliposomeshelpstoestimatethebehaviorofthe
druginbiologicalsystem.
•Liposomesaremixtureofencapsulatedandunencapsulateddrugfractions.
•The%ofdrugencapsulationisdonebyfirstseparatingthefreedrugfraction
fromencapsulateddrugfraction.
4.Phasebehavior
•Attransitiontemperatureliposomesundergoreversiblephasetransition.
•Thetransitiontemperatureistheindicationofstabilitypermeabilityandalso
indicatestheregionofdrugentrapment.
•DonebyDSC.
5.DrugReleaseRate
•Therateofdrugreleasefromtheliposomescanbedeterminedbyinvivo
assayswhichhelpstopredictthepharmacokineticsandbioavailabilityofthe
drug.
•Howeverinvivostudiesarefoundtobemorecomplete.
Evaluationofliposomes

60. Benefits of drug load in liposomes
Sr.No. Benefits of drug load in liposome Examples
1. Improvedsolubilityoflipophilicand
amphiphilicdrugs
AmphotericinB,porphyrins,minoxidil,some
peptides,andanthracyclines,
respectively;hydrophilicdrugs,suchas
anticanceragentdoxorubicinoracyclovir
2. Passivetargetingtothecellsofthe
immunesystem,especiallycellsofthe
mononuclearphagocyticsystem
Antimonials,amphotericinB,porphyrins,
vaccines,immunomodulators
3. Sustainedreleasesystemofsystemically
orlocallyadministeredliposomes
Doxorubicin,cytosinearabinoside,cortisones,
biologicalproteinsorpeptidessuchas
vasopressin
4. Site-avoidancemechanism DoxorubicinandamphotericinB
5. Site-specifictargeting Anti-inflammatorydrugs,anti-cancer,anti-
infection
6. Improvedtransferofhydrophilic,
chargedmolecules
Antibiotics,chelators,plasmids,andgenes
7. Improvedpenetrationintotissues Corticosteroids,anesthetics,andinsulin

61. •Liposomesasdrugorproteindeliveryvehicles.
•Liposomeinantimicrobial,antifungal(lung
therapeutics)andantiviral(antiHIV)therapy.
•Intumortherapy.
•Ingenetherapy.
•Inimmunology.
•Liposomesasartificialbloodsurrogates.
APPLICATIONS