2Contents Introduction Structure of niosomes Materials used in the preparation of niosomesAdvantages & disadvantages of niosomesFormation of niosomes from proniosomesMethods of preparationSize reduction methods & drug loadingEncapsulation of drugs & removal of unentrapped drugCharacterization of niosomesStability of niosomesApplicationsRecent advances in niosomesConclusionReferences
3INTRODUCTION Niosomes definition Niosomes are essentially non-ionic surfactant based multilamellar or unilamellar vesicles in which an aqueous solution of solute (s) is entirely enclosed by a membrane resulted from the organization of surfactant macromolecules as bilayers”Niosomes made-up of self assembly of hydrated nonionic surfactant molecules (eg: tweens and spans) with or with out cholesterol and dicetyl phosphate.The assembly into closed bilayers is rarely spontaneous and usually involves some input of energy such as physical agitation or heat.
4Niosomes also called as Nonionic surfactant vesicles or NSV s Nios = non ionic surfactantsomes = vesiclesNSVS results from the self assembly of hydrated surfactant monomers results in closed bilayer structuresDrug carriersBiodegradable, biocompatible and non immunogenicLarge qty of material can be encapsulatedVery small ,microscopic in size.Most surface active agents when immersed in water yield micellar structures, how ever some surfactants can yield bilayered vesicles which are niosomes
6COMPARISION OF NIOSOMES VS LIPOSOMES Niosomes behave in-vivo like liposomes, prolonging the circulation of entrapped drug And altering its organ distribution and metabolic stabilityIn both basic unit of assembly is Amphiphiles, but they phospholipids in liposomes and nonionic surfactants in niosomes.Both can entrap hydrophilic and lipophilic drugs.Both have same physical properties but differ in their chemical composition.Niosomes has higher chemical stability than liposomes.Niosomes made of uncharged single chain surfactant moleculesLiposomes made of neutral or charged double chain phospholipids.Niosomes and liposomes are similar in-FunctionIncrease the bioavailabilityDecrease the clearenceUsed for targeted drug deliveryProperties depends on both composition of bilayer and method of preparation
7ADVANTAGES OF NIOSOMES OVER LIPOSOMES Ester bonds of phospholipids are easily hydrolyzed, this can lead to phosphoryl migration at low PHPeroxidation of unsaturated phospholipids.This requires that purified phospholipids and liposomes have to be stored and handled in an inert (N2) atmosphere this problem is not seen with niosomes because these are made up of nonionic surfactants & these does require special storage conditionPhospholipid raw materials are naturally occurring substances and as such require extensive purification thus making them costlyNiosomes has high adjuvanticity when compared to liposomes
8ADVANTAGES OF NIOSOMES They are osmotically active and stable.They increase the stability of the entrapped drug Handling and storage of surfactants do not require any special conditionsCan increase the oral bioavailability of drugsCan enhance the skin penetration of drugsThey can be used for oral, parenteral as well topical useIn cosmetics was first done by L’Oreal as they offered the following advantages:The vesicle suspension being water based offers greater patient compliance over oil based systemsSince the structure of the niosome offers place to accommodate hydrophilic, lipophilic as well as amphiphilic drug moieties, they can be used for a variety of drugs.The characteristics such as size, lamellarity etc. of the vesicle can be varied depending on the requirement.The vesicles can act as a depot to release the drug slowly and offer a controlled release.
9The surfactants are biodegradable, biocompatible, and non-immunogenic Improve the therapeutic performance of the drug by protecting it from the biological environment and restricting effects to target cells, thereby reducing the clearance of the drug.The Niosomal dispersions in an aqueous phase can be emulsified in a non-aqueous phase to control the release rate of the drug and administer normal vesicles in external non-aqueous phase.USES OF NIOSOMESTopical niosomes may serve as -As solubilization matrix,As a local depot for sustained release of dermally active compounds,As penetration enhancers,As rate-limiting membrane barrier for the modulation of systemic absorption of drugs
10DISADVANTAGES/PROBLEMS ASSOCIATED WITH NIOSOMES As high input of energy is required in the size reduction of niosomes, they aggregate and fuse togeather on prolonged storagePhysicochemical instability remains the major problem in the development of Niosomal system at industrial levelsDISTRIBUTION OF DRUGS IN NIOSOMESCarriers for both lipophilic & hydrophilic drugsHighly hydrophilic drugs are exclusively located in the aqueous domainHighly lipophilic drugs are entrapped within the lipid bilayers of the niosomesDrugs with intermediary partition coefficient equilibrate b/w lipid & aqueous domains
11Different Niosomes1. Bola-Surfactant containing Niosomes:Niosomes made of alpha,omega-hexadecyl-bis-(1-aza-18-crown-6) (Bola-surfactant)-Span 80-cholesterol (2:3:1 molar ratio) are named as Bola-Surfactant containing Niosomes.2. Proniosomes:A dry product which may be hydrated immediately before use to yield aqueous Niosome dispersions. These ‘proniosomes’ minimize problems of Niosome physical stability such as aggregation, fusion and leaking, and provide additional convenience in transportation, distribution, storage, and dosing.In short;1. Carrier + Surfactants = Proniosomes2. Proniosomes + H2O = NiosomesIn case of Frusemide delivery in the body, it has been found that proniosomal formulations have been found effective
12MOLECULAR GEOMETRY & VESICLE FORMATION Concept of Critical Packing Parameter (Israelachvili, 1985)Prediction of vesicle forming ability is not a simply a matter of HLBCPP = v/lca0wherev - hydrophobic group volume,lc - critical hydrophobic group length anda0 - area of the hydrophilic head groupCPP between0.5 and 1 likely to form vesicles.<0.5 (indicating a large contribution from the hydrophilic head group area) is said to give spherical micelles.>1 (indicating a large contribution from the hydrophobic group volume) should produce inverted micelles, the latter presumably only in an oil phase, or precipitation would occur.
14MATERIALS USED IN THE PREPARATION OF NIOSOMES Non ionic surfactants – AmphiphilesSterols like cholesterolCharge inducersNon-ionic surfactant structureHydrophilic head groups found in vesicle forming surfactantsGlycerol head groupsEthylene oxide head groupsCrown ether head groupsPolyhydroxy head groupsSugar head groups + amino acidsSugar head groups (galactose, mannose, glucose, lactose)Hydrophobic moietyOne or two alkyl or perfluoroalkyl groups or in certain cases a singlesteroidal group.Alkyl group chain length is usually from C12–C18 (one, two or threealkyl chains.
15Increases drug loading of water soluble drugs in MLV Perfluoroalkyl surfactants that form vesicles possess chain lengths as short as C10Additionally crown ether amphiphiles bearing a steroidal C14 alkyl or C16 alkyl hydrophobic unit have been shown to form vesicles.The water soluble detergent polysorbate 20 also forms niosomes in the presence of cholesteroltwo portions of the molecule are linked by ether, ester & amide linkages..STEROIDS – CholesterolImproves the fluidity of the bilayer.Minimizes leaching out of water soluble drug.Systems resulting in less leaky vesicles.Improves stability in biological fluids – reduce interactionwith plasma proteinsCHARGE INDUCERS – Dicetyl Phosphate, Sod. Cholate, StearylaminePrevents aggregationIncreases drug loading of water soluble drugs in MLV
16FACTORS GOVERNING THE SELF ASSEMBLY OF NIOSOMES Non ionic surfactant structureMembrane additivesNature of the encapsulated material/drugSurfactant & lipid levelsTemperature of hydration
17FACTORS INFLUENCING THE NIOSOMAL PHYSICAL CHEMISTRY
18Formation of niosomes from proniosomes Another method of producing niosomes is to coat a water-soluble carrier such as sorbitol with surfactant.The result of the coating process is a dry formulation. In which each water-soluble particle is covered with a thin film of dry surfactant.This preparation is termed “Proniosomes”.The niosomes are recognized by the addition of aqueous phase at T > Tm and brief agitation.T = Temperature Tm = mean phase transition temperature.
19LUV Folds to form vesicles Surfactant swells hydration Method of preparationA. Ether injection methodsurfactant : cholesterol(150µmol) ether(20ml) gauge needle(.25ml/min)aqueous phase(4ml at 60 0 c)Mechanism of action:Slow vapourization of solvent resulting into a ether gradient extending across the interfacial lipid/surfactant monolayer at ether water interface results in the formation of bilayer sheet which eventually folds on itself to form sealed vesicles.B. HAND SHAKING METHOD (THIN FILM TECNIQUE)Surfactant : cholesterol(150µmol) diethyl ether(10ml) evaporatedin rotaryevaporaterLUVFolds to form vesiclesSurfactant swellshydration
20C. SONICATION surfactant : cholesterol (150µmol) Probe sonication(3min at 60 0 c)Aqueous phasein vial(2ml)Ultrasonic vibrationULVMLVProbe sonicator used when sample size is small volumeBath sonicator used for larger volumesD. REVERSE PHASE EVAPORATIONChloroform& phosphate buffersurfactantW/O emulsionSonication & evaporationhydrationvesicles
21E . MICROFLUIDIZATIONThis method is based on submerged jet principle in which two fluidized streams interact at ultra high velocities, in precisely defined micro channels within the interaction chamber.The impingement of thin liquid sheet along a common front is arranged such that the energy supplied to the system remains within the area of niosomes formation.The result is a greater uniformity, smaller size and better reproducibility of niosomes formedMETHODS USED FOR NIOSOME PREPARATION IN INDUSTRIAL SCALE ARENovasomeHandjani – Vila et al. - for larger qty i.e. Kg of dispersions
22Surfactant, cholesterol, diacetyl phosphate in chloroform F. Multiple membrane extrusion methodSurfactant, cholesterol, diacetyl phosphate in chloroformThin films by evaporationHydrated with aqc drug solnSuspension extruded through polycarbonate membranesNiosomes(of controlled size)Upto 8 passages forms vesiclesG. Trans membrane pH gradient (inside acidic) Drug Uptake Process (Remote Loading)Surfactant, cholesterol in chloroformHydration with 300mM citric acidevaporationMLVP H with 1M disodium phosphateFrozen,thawed& sonicated(Niosomal suspension)Acq drug soln(10mg/ml)Heating at 60 0 c forms niosomes
23This method does uses organic solvents - adv H. BUBBLE METHODThis method does uses organic solvents - advThe bubbling unit consists of round-bottomed flask with three necks positioned in water bath to control the temperature.Water-cooled reflux and thermometer is positioned in the first and second neck and nitrogen supply through the third neckHomogenizationFor 15 minDissolved in buffer at p H 7.4 at 70 0 cSurfactant, cholesterolniosomesBubbled at 70 0 c using N 2 gasMICELLAR SOLUTION METHODSMixed micellar solutionEsterases ,non ionic surfactant , NIOSOMESCharged inducerEsterases enzymes cleavage the micellar solution
24SIZE REDUCTION METHODS Probe sonication nmExtrusion method in the range of 140nmSonication & filtration in the range of 200nmMicrofluidizer <50nmHigh pressure homogenization <100nmDRUG LOADINGActive loading / Remote loadingPassive loading
25ENCAPSULATION OF DRUGS IN NIOSOMES Encapsulation volume/Trapped volume Volume of aqueous solution entrapped in niosomes per moleof surfactant (µL/µmol surfactant)Encapsulation EfficiencyIt is determined after separation of unentrapped drug, on complete vesicle disruption by using about 1 ml of 2.5% sodium lauryl sulphate, briefly homogenized and centrifuged and supernatant assayed for drug after suitable dilution.% EncapsulationDrug entrapped in niosomesx 100Total drug added
26The effect of the choice of niosome forming surfactant on the properties of the niosome dispersion
27The effect of the nature of the encapsulated drug on the properties of the niosome dispersion.
29DRUGS INCORPORATED INTO NIOSOMES BY VARIOUS METHODS Method of preparationDrug incorporatedEther InjectionSodium stibogluconate Doxorubicin Hand ShakingMethotrexate SonicationReverse phase evaporation9-desglycinamide8-arginineVasopressinOestradiolDiclofenac sodium
30. Characterization of niosomes a) Entrapment efficiencyThe drug remained entrapped in niosomes is determined by complete vesicle disruption using 50% n-propanol or 0.1% Triton X-100 and analyzing the resultant solution by appropriate assay method for the drug. Where,Entrapment efficiency (EF) = ( amount entrapped / total amount) x 100b) Vesicle diameterNiosomes, similar to liposomes, assume spherical shape and so their diameter can be determined using –light microscopy,photon correlation microscopyfreeze fracture electron microscopy.Freeze thawing (keeping vesicles suspension at –20°C for 24 hrs and then heating to ambient temperature) of niosomes increases the vesicle diameter, which might be attributed to fusion of vesicles during the cycle
31(c) In-vitro releasedialysis tubingA dialysis sac is washed and soaked in distilled water.The vesicle suspension is pipetted into a bag made up of the tubing and sealed.The bag containing the vesicles is placed in 200 ml of buffer solution in a 250 ml beaker with constant shaking at 25°C or 37°C.At various time intervals, the buffer is analyzed for the drug content by an appropriate assay methodFactors affecting vesicles size, entrapment efficiency and release characteristicsa) Drugentrapment of drugs in niosomes increase the vesicle size by-1.interaction of solute with surfactant head groups2.increasing the charge3.mutual repulsions of the surfactant bilayersIn PEG coated vesicles, some of the drug entrapped in long PEG chains there by reducing the charge
32b) Amount and type of surfactant Hydrophilic Lipophilic Balance (HLB) is a good indicator of the vesicle forming ability of any surfactant.With the sorbitan monostearate (Span) surfactants, a HLB number of between 4 and 8 was found to be compatible with vesicle formationBilayers of vesicles are in gel or liquid state depending on-1. Temp2. Type of liquid or surfactant3. CholesterolSurfactants or lipids are characterized by gel - liquid phase transition temp (TC)TC of surfactant also effect entrapment efficiency i.e., span 60 has higher TC so better entrapmentc) cholesterol content & chargeCholesterol increase the hydrodynamic diameter & entrapment efficiency
33charge - induced by stearylamine & Diacetyl phosphate Action is two ways –Increase the chain order of liquid state bilayersDecrease the chain order of gel state bilayersat high cholesterol conc gel state less ordered liquid crystalline phaseIncrease in cholesterol content-Increase the rigidity of bilayersDecrease the release rate of encapsulated materialcharge - induced by stearylamine & Diacetyl phosphateIncrease the interlamellar distance b/w the successive bilayers in multilamellarvesiclesOverall greater entrapped volume
34d) Methods of preparation Hand shaking method forms vesicles with greater diameter ( nm) compared to the ether injection method ( nm)Small sized niosomes can be produced by Reverse Phase Evaporation (REV) method Micro fluidization method gives greater uniformity and small size vesicles.Niosomes also prepared by trans membrane pH gradient (inside acidic) drug uptake process , showed greater entrapment efficiency and better retention of druge) Resistance to osmotic stressAddition of a hypertonic salt solution to a suspension of niosomes brings about reduction in diameter.In hypotonic salt solution, there is initial slow release with slight swelling of vesicles probably due to inhibition of eluting fluid from vesicles, followed by faster release, which may be due to mechanical loosening of vesicles structure under osmotic stress.
35CHARACTERIZATION OF NIOSOMES Mean Size & Size distribution - Electron MicroscopyDynamic Light Scattering (PCS)molecular sieve chromatographySurface Potential & Surface pH Micro electrophoresisNo of lamellae Small angle X ray Scattering, NMR, Electron microscopyStructural & Motional behaviorof lipids DSC, ESR, NMRSurface Chemical Analysis NMRBilayer formation X cross formation under lightpolarization microscopyMembrane rigidity mobility of fluorescence probe as afunction of temp
36STABILITY OF NIOSOMESStability in bufferStability in hypertonic mediaStability in hypotonic mediaStability in – vivoStability is also influenced by –Surfactant/lipid ratioEncapsulated drugTemperature of storageDetergents
37Applications Targeting of bioactive agents a) To reticulo - endothelial system (RES)b) To organs other than RES2) NeoplasiaDoxorubicin dose dependant irreversible cardio toxic effect.Niosomal delivery of this drug to mice bearing S-180 tumor increased their life span and decreased the rate of proliferation of sarcoma.Niosomal entrapment increased the half-life of the drug, prolonged its circulation and altered its metabolism.Intravenous administration of methotrexate entrapped in niosomes to S-180 tumor bearing mice resulted in total regression of tumor and also higher plasma level and slower elimination.
383) Leishmaniasissodium stibogluconate4) Niosomes in Oral & Opthalmic drug deliveryOral Ergot alkaloidsOpthalmic Cyclopentolate (polysorbate – 20 & cholesterol)5) Diagnostic imaging with niosomesIopromide6) Anti infective agentsRifampicin7) Anti cancer therapymethotrexate8) Niosomes as Vaccine Adjuvants9) Delivery of peptide drugs9-desglycinamide, 8-arginine, vasopressin
3910) Immunological application 11) Carriers for haemoglobin 12) Transdermal delivery of drugs Oestradiol 13) Other applecations a) Sustained release b) Localized drug action c) Cosmetics 14) Niosomes also used as drug carrier Ciprofloxacin & Norfloxacin Doxorubicin Indomethacin Pentoxyphillin Diclofenac Sodium 9 – desglycinamide 8 – Arginine Vasopressin Propylthiouracil
40Suitable niosome sizes for particular routes of administration
41RECENT ADVANCES IN NIOSOMES Combination of PEG and glucose conjugates on the surface of niosomes significantly improved tumor targeting of an encapsulated paramagnetic agent assessed with MR imaging in a human carcinoma xenograft model.Phase I and phase II studies were conducted for Niosomal methotrexate gel in the treatment of localized psoriasis. These studies suggest that niosomal methotrexate gel is more efficacious than placebo and marketed methotrexate gel.A research article was published that Acyclovir entrapped niosomes were prepared by Hand shaking and Ether injection methods increases the oral bioavailabilityLancome has come out with a variety of anti-ageing products which are based on niosome formulations
42ConclusionThe concept of incorporating the drug into liposomes or niosomes for a better targeting of the drug at appropriate tissue destination is widely accepted by researchers and academicians.Niosomes represent a promising drug delivery module.They presents a structure similar to liposome and hence they can represent alternative vesicular systems with respect to liposomes, due to the niosome ability to encapsulate different type of drugs within their multi environmental structure.Niosomes are thoughts to be better candidates drug delivery as compared to liposomes due to various factors like cost, stability etc.Various type of drug deliveries can be possible using niosomes like targeting, ophthalmic, topical, parenteral, etc. Niosomes can also serve better aid in diagnostic imaging and vaccine adjuvant in pharmaceutical industry.Niosomes are considered as promising controlled drug delivery carrier which increase the half life of drugs and helps in formulating prolonged/controlled acting dosage formsNiosomes have great drug delivery potential for targeted delivery of anti-cancer, anti infective agents.
431) S.P.Vyas, R.K.Khar., Targetted and controlled drug delivery. REFERENCES1) S.P.Vyas, R.K.Khar., Targetted and controlled drug delivery.2) N.K.Jain., Advances in controlled and novel drug delivery.3)James Swarbrick, Encyclopedia of pharmaceutical technology, third edition , vol-24) en.wikipedia.org5) Informa Healthcare – Journal of Liposome Research6) AAPS PharmaSciTec.com7) Pharmainfo.net8) I. F. Uchegbu, S.P. Vyas : International Journal of Pharmaceutics 172 (1998) 33–709)Journal of Pharmacy Research Vol.1.Issue 2. Oct-December 2008