Introduction Structure Niosomes Vs. Liposome Advantages & Disadvantages Properties of Niosomes Method of Manufacturing Evaluation of Niosomes Applications Marketed products

1. 1
NIOSOMES
Dr. Anil Pethe
Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management,
SVKM’S NMIMS, Mumbai

2. Introduction
Structure
Niosomes Vs. Liposome
Advantages & Disadvantages
Properties of Niosomes
Method of Manufacturing
Evaluation of Niosomes
Applications
Marketed products
Contents

3. • Niosomes are non-ionic surfactant based
unilamellar or multilamellar bilayer vesicles
upon hydration of non ionic surfactants with or
without incorporation of cholesterol .
• The niosomes are very small, and microscopic in
size. Their size lies in the nanometric scale.
• Niosomes are a novel drug delivery system, in
which the medication is encapsulated in a
vesicle.
• Both hydrophilic & lipophilic drugs ,entrap
either in the aqueous layer or in lipid layer.
Introduction

4. • These vesicular systems are similar to liposomes that can be used as
carriers of amphiphilic and lipophilic drugs.
• It is less toxic and improves the therapeutic index of drug by restricting its
action to target cells.
Structure of Niosomes

5. Niosomes Vs. Liposome
Liposomes Niosomes
Vesicles made up of concentric bilayer of
phospholipids
Vesicles made up of surfactants with or without
incorporation of cholesterol.
Size ranges from 10-3000nm Size ranges from 10-100nm
Comparatively expensive Inexpensive
Special storage condition are required No such special requirement
Phospholipids used are unstable Non-ionic surfactants are stable
Comparatively more toxic Less toxic

6. • They are osmotically active and stable.
• They increase the stability of the entrapped drug.
• The vesicle suspension being water based offers greater patient compliance over oil based
systems
• Since the structure of the niosome offers place to accommodate hydrophilic, lipophilic as
well as ampiphilic drug moieties, they can be used for a variety of drugs.
• The vesicles can act as a depot to release the drug slowly and of controlled release.
• Biodegradable, non-immunogenic and biocompatible.
Advantages

7. • Aggregation
• Fusion
• Leaking of entrapped drug
• Hydrolysis of encapsulated drugs which limiting the shelf life of the
dispersion.
Disadvantages

8. Classification of Niosomes
The niosomes are classified as a function of the number of bilayer (e.g. MLV,
SUV) or as a function of size. (e.g. LUV, SUV) or as a function of the method of
preparation
The various types of niosomes are described below:
i) Multi lamellar vesicles (MLV, Size=>0.05 µm)
ii) Large unilamellar vesicles (LUV, Size=>0.10 µm).
iii) Small unilamellar vesicles (SUV, Size=0.025-0.05 µm)

9. 1. Multilamellar vesicles (MLV): It consists of a number of bilayer surrounding the aqueous
lipid compartment separately. The approximate size of these vesicles is 0.5-10 µm
diameter. Multilamellar vesicles are the most widely used niosomes. These vesicles are
highly suited as drug carrier for lipophilic compounds.
2. Large unilamellar vesicles (LUV): Niosomes of this type have a high aqueous/lipid
compartment ratio, so that larger volumes of bio-active materials can be entrapped with a
very economical use of membrane lipids.
3. Small unilamellar vesicles (SUV): These small unilamellar vesicles are mostly prepared
from multilamellar vesicles by sonication method, French press extrusion electrostatic
stabilization is the inclusion of dicetyl phosphate in 5(6)-carboxyfluorescein (CF) loaded
Span 60 based niosomes
Classification of Niosomes

10. Niosomes mainly contains following types of components:
Non-ionic surfactants:
• Selection of surfactant should be done on the basis of HLB value.
• As Hydrophilic Lipophilic Balance (HLB) is a good indicator of the vesicle forming ability
of any surfactant, HLB number in between 4 and 8 was found to be compatible with
vesicle formation.
• It is also reported that the hydrophilic surfactant owing to high aqueous solubility. on
hydration do not reach a state of concentrated systems in order to allow free hydrated
units to exist aggregates and coalesced to form lamellar structure.
Components of Niosomes

11. a) Alkyl ethers: some surfactants for the preparation of niosomes containing
drugs/chemicals as:
1) Surfactant-I (Mol.Wt.473) is C16 monoalkyl glycerol ether with average of three glycerol units.
2) Surfactant-II (Mol.Wt.972) is diglycerol ether with average of the seven glycerol units.
3) Surfactant III (Mol.Wt.393) is ester linked surfactant.
a) Alkyl esters: Sorbitan esters are most preferred surfactant used for the preparation of
niosomes amongst this category of surfactants. Vesicles prepared by the
polyoxyethylene sorbitan monolaurate are relatively soluble than other surfactant
vesicles]. For example polyoxyethylene (polysorbate 60) has been utilized for
encapsulation of diclofenac sodium.
b) Alkyl amides: Alkyl amide (e.g. galactosides and glucosides) have been utilized to
produce niosomal vesicles
c) Fatty acid and amino acid compounds: Long chain fatty acids and amino acid moieties
have also been used in some niosomes preparation.
Components of Niosomes (cont.)

12. Cholesterol:
• Steroids are important components of the cell membrane and their presence in
membrane affect the bilayer fluidity and permeability. Cholesterol is a steroid derivative,
which is mainly used for the formulation of niosomes.
• Although it may not show any role in the formation of bilayer, its importance in
formation of niosomes and manipulation of layer characteristics can not be discarded. In
general, incorporation of cholesterol affect properties of niosomes like membrane
permeability, rigidity, encapsulation efficiency, ease of rehydration of freeze dried
niosomes and their toxicity.
• As a result of this, the niosome become less leaky in nature.

13. Charged molecule:
• Some charged molecules are added to niosomes to increase stability of niosomes
by electrostatic repulsion which prevents coalescence.
• The negatively charged molecules used are diacetyl phosphate (DCP) and
phosphotidic acid. Similarly, stearylamine (STR) and stearyl pyridinium chloride
are the well known positively charged molecules used in niosomal preparations.
• These charged molecules are used mainly to prevent aggregation of niosomes.

14. Factors affecting Niosomes formation
Nature of
surfactant
Inclusion of
a charged
molecule
Factors
Structure
of
surfactant
Temperature
of hydration
Nature of
encapsulated
drug

15. • A surfactant used for preparation of niosomes must have a hydrophilic head and
hydrophobic tail. The hydrophobic tail may consist of one or two alkyl or
perfluoroalkyl groups or in some cases a single steroidal group.
• The ether type surfactants with single chain alkyl as hydrophobic tail is more
toxic than corresponding dialkyl ether chain.
• The ester type surfactants are chemically less stable than ether type surfactants
and the former is less toxic than the latter due to ester-linked surfactant
degraded by esterase’s to triglycerides and fatty acid in vivo.
• The surfactants with alkyl chain length from C12- C18 are suitable for preparation
of niosomes.
• Surfactants such as C16EO5 (poly-oxyethylene cetyl ether) or C18EO5
(polyoxyethylene steryl ether) are used for preparation of polyhedral vesicles.
• Span series surfactants having HLB number of between 4 and 8 can form
vesicles.
Nature of surfactant

16. • The geometry of vesicle to be formed from surfactants is affected by its structure, which
is related to critical packing parameters.
• On the basis of critical packing parameters of surfactants, we can predict geometry of
vesicle to be formed.
• Critical packing parameters can be defined using following equation,
CPP (Critical Packing Parameters) = v/lc ×a0
• Where v = hydrophobic group volume,
• lc = the critical hydrophobic group length,
• a0= the area of hydrophilic head group.
• From the critical packing parameter value type of miceller
structure formed can be ascertained as given below,
If CPP < ½, then formation of spherical micelles,
If ½ < CPP < 1, then formation of bilayer micelles,
If CPP > 1, then formation inverted micelles.
Structure of surfactant

17. • The mean size of niosomes increases proportionally with increase in the HLB of
surfactants like Span 85 (HLB 1.8) to Span 20 (HLB 8.6) because the surface free
energy decreases with an increase in hydrophobicity of surfactant.
• The bilayers of the vesicles are either in the so-called liquid state or in gel state,
depending on the temperature, the type of lipid or surfactant and the presence of
other components such as cholesterol.
• In the gel state, alkyl chains are present in a well-ordered structure, and in the
liquid state, the structure of the bilayers is more disordered.
• The surfactants and lipids are characterized by the gel-liquid phase transition
temperature (TC).
• Phase transition temperature (TC) of surfactant also effects entrapment efficiency
i.e. Span 60 having higher TC, provides better entrapment.
Amount and type of surfactant

18. • The stable niosomes can be prepared with addition of different additives along
with surfactants and drugs.
• Niosomes formed have a number of morphologies and their permeability and
stability properties can be altered by manipulating membrane characteristics by
different additives.
• In case of polyhedral niosomes formed from C16G2, the shape of these
polyhedral niosome remains unaffected by adding low amount of solulan C24
(cholesteryl poly-24-oxyethylene ether), which prevents aggregation due to
development of steric hindrance.
• The mean size of niosomes is influenced by membrane composition such as
Polyhedral niosomes formed by C16G2: solulan C24 in ratio (91:9) having bigger
size (8.0 ±0.03mm) than spherical/tubular niosomes formed by C16G2:
cholesterol: solulan C24 in ratio (49:49:2)(6.6±0.2mm).
• Addition of cholesterol molecule to niosomal system provides rigidity to the
membrane and reduces the leakage of drug from niosome.
Membrane Composition

19. • The physico-chemical properties of encapsulated drug influence charge
and rigidity of the niosome bilayer.
• The drug interacts with surfactant head groups and develops the charge
that creates mutual repulsion between surfactant bilayers and hence
increases vesicle size.
• The aggregation of vesicles is prevented due to the charge development
on bilayer.
• In polyoxyethylene glycol (PEG) coated vesicles, some drug is entrapped
in the long PEG chains, thus reducing the tendency to increase the size.
• The hydrophilic lipophilic balance of the drug affects degree of
entrapment.
Nature of Encapsulated Drug

20. • Hydration temperature influences the shape and size of the niosome.
• For ideal condition it should be above the gel to liquid phase transition
temperature of system.
• Temperature change of niosomal system affects assembly of surfactants into
vesicles and also induces vesicle shape transformation.
• Arunothayanun et al. reported that a polyhedral vesicle formed by C16G2:
solulan C24 (91:9) at 25°C which on heating transformed into spherical vesicle at
48°C, but on cooling from 55°C, the vesicle produced a cluster of smaller
spherical niosomes at 49°C before changing to the polyhedral structures at 35°C.
• In contrast vesicle formed by C16G2: cholesterol: solulan C24 (49:49:2) shows
no shape transformation on heating or cooling.
• Along with the above mentioned factors, volume of hydration medium and time
of hydration of niosomes are also critical factors. Improper selection of these
factors may result in formation of fragile niosomes or creation of drug leakage
problems.
Temperature of Hydration

21.  Hand Shaking method
 Reverse phase evaporation technique
 Ether Injection method
 Multiple membrane extrusion method
 Bubble method
 Sonication
 From Proniosomes
Method of Preparation of Niosomes

22. Common stages of all Method of Preparation of Niosomes

23. • The mixture of vesicles forming ingredients
like surfactant and cholesterol are dissolved in
a volatile organic solvent (diethyl ether,
chloroform or methanol) in a round bottom
flask.
• The organic solvent is removed at room
temperature (20°C)using rotary evaporator
leaving a thin layer of solid mixture deposited
on the wall of the flask.
• The dried surfactant film can be rehydrated
with aqueous phase at 0- 60°C with gentle
agitation.
• This process forms typical multilamellar
Niosomes.
Hand shaking method

24. • Cholesterol and surfactant (1:1) are dissolved
in a mixture of ether and chloroform.
• An aqueous phase containing drug is added
to this and the resulting two phases are
sonicated at 4-5°C.
• The clear gel formed is further sonicated after
the addition of a small amount of phosphate
buffered saline (PBS).
• The organic phase is removed at 40°C under
low pressure.
• The resulting viscous niosome suspension is
diluted with PBS and heated on a water bath
at60°C for 10 min to yield Niosomes.
• It was reported that the preparation of
Diclofenac Sodium Niosomes using Tween 85
by this method
Reverse phase evaporation technique

25. • This method provides a means of making
Niosomes by slowly introducing a solution of
surfactant dissolved in diethyl ether into warm
water maintained at 60°C.
• The surfactant mixture in ether is injected
through 14-gauge needle into an aqueous
solution of material.
• Vaporization of ether leads to formation of
single layered vesicles.
• Depending upon the conditions used the
diameter of the vesicle range from 50 to 1000
nm
Ether Injection method

26. • A mixture of surfactant, cholesterol, and
diacetyl phosphate in chloroform is
made into thin film by evaporation.
• The film is hydrated with aqueous drug
solution and the resultant suspension
extruded through polycarbonate
membranes, which are placed in a series
for up to eight passages.
• This is a good method for controlling
niosome size.
Multiple membrane extrusion method

27. • The oil in water (o/w) emulsion is prepared from an organic solution
of surfactant, cholesterol, and an aqueous solution of the drug.
• The organic solvent is then evaporated, leaving niosomes dispersed
in the aqueous phase.
Emulsion method

28. • This method does not require expensive organic phase.
• Here, the mixture of lipids and surfactant is first melted and then
injected into a highly agitated heated aqueous phase containing
dissolved drug.
• Here, the drug can be dissolved in molten lipid and the mixture will
be injected into agitated, heated aqueous phase containing
surfactant.
Lipid injection method

29. • It is novel technique for the one step preparation of liposomes and
niosomes without the use of organic solvents.
• The 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 neck.
• Cholesterol and surfactant are dispersed together in this buffer (pH 7.4)
at70°C, the dispersion mixed for 15 seconds with high shear
homogenizer and immediately afterwards “bubbled” at 70°C using
nitrogen gas.
Bubble Method

30. 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 thin film of dry surfactant
 This preparation is called as “proniosomes”
 The niosomes are recognized by the addition of aqueous phase at T˃Tm and brief
agitation
(where T- Temperature and TM- Phase transition temperature)

31. • A typical method of production of the
vesicles is by Sonication of solution.
• In this method an aliquot of drug
solution in buffer is added to the
surfactant/cholesterol mixture in a 10-
ml glass vial.
• The mixture is probe sonicated at
60°C for 3 minutes using a sonicator
with a titanium probe to yield
Niosomes.
Sonication Method

32. • Micro fluidization is a recent technique to
prepare unilamellar vesicles of defined
size distribution.
• This 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 formed.
Micro fluidization Method

33. Dialysis
• The aqueous niosomal dispersion is dialyzed in dialysis tubing against
phosphate buffer or normal saline or glucose solution.
Gel Filtration
• The unentrapped drug is removed by gel filtration of niosomal dispersion
through a Sephadex-G-50 column and elution with phosphate buffered
saline or normal saline.
Centrifugation
• The niosomal suspension is centrifuged and the supernatant is
evaporated. The pellet is washed and then re-suspended to obtain a
niosomal suspension free from un-entrapped drug.
Separation of unentrapped drug:

34. a) Size, Shape and Morphology Freeze Fracture Electron Microscopy:-
Visualize the vesicular structure of surfactant based vesicles. Photon
Correlation spectroscopy :- Determine mean diameter of the vesicles.
Electron Microscopy :- Morphological studies of vesicles.
b) Entrapment efficiency After preparing niosomal dispersion, unentrapped
drug is separated by dialysis and the drug remained entrapped in niosomes
is determined by complete vesicle disruption using 50% n-propanol or
0.1% Triton X-100 and analysing the resultant solution by appropriate
assay method for the drug.
c) Vesicle Surface Charge Determined by measurement of electrophoretic
mobility and expressed in expressed in terms of zeta potential
d) In vitro studies
Evaluation of Niosomes

35. Ophthalmic drug delivery
 From ocular dosage form like ophthalmic solution, suspension and ointment it is
difficult to achieve excellent bioavailability of drug due to the tear production,
impermeability of corneal epithelium, non-productive absorption and transient
residence time.
 But niosomal and liposomal delivery systems can be used to achieve good
bioavailability of drug.
 Bio adhesive-coated niosomal formulation of acetazolamide prepared from span 60,
cholesterol stearylamine or dicetyl phosphate exhibits more tendencies for
reduction of intraocular pressure as compared to marketed formulation
(Dorzolamide)
Application of Niosome

36. Localized Drug Action
 Drug delivery through Niosomes is one of the approaches to achieve
localized drug action, since their size and low penetrability through
epithelium and connective tissue keeps the drug localized at the site of
administration.
 Localized drug action results in enhancement of efficacy of potency of the
drug and at the same time reduces its systemic toxic effects e.g. Antimonials
encapsulated within niosomes are taken up by mononuclear cells resulting
in localization of drug, increase in potency and hence decrease both in dose
and toxicity.
 The evolution of niosomal drug delivery technology is still at an infancy
stage, but this type of drug delivery system has shown promise in cancer
chemotherapy and anti-leishmanial therapy.
Application of Niosome

37. Diagnostic imaging with niosomes
 Niosomal system can be used as diagnostic agents.
 Conjugated niosomal formulation of gadobenatedimeglcemine with [N-
palmitoylglucosamine (NPG)], PEG4400, and both PEG and NPG exhibit
significantly improved tumor targeting of an encapsulated paramagnetic agent
assessed with MR imaging
Application of Niosome

38. Transdermal delivery of drugs by niosomes
 An increase in the penetration rate has been achieved by transdermal
delivery of drug incorporated in niosomes as slow penetration of drug
through skin is the major drawback of transdermal route of delivery
for other dosage forms.
 The topical delivery of erythromycin from various formulations
including niosomes has studied on hair less mouse and from the
studies, and confocal microscopy, it was found that nonionic vesicles
could be formulated to target pilosebaceous glands
Application of Niosome

39. Niosome as a carrier for Hemoglobin
 Niosomal suspension shows a visible spectrum superimposable
onto that of free hemoglobin so can be used as a carrier for
hemoglobin.
 Vesicles are also permeable to oxygen and hemoglobin
dissociation curve can be modified similarly to non-encapsulated
hemoglobin
Application of Niosome

40. Application of Niosome
Delivery of peptide drugs
 Niosomal entrapped oral delivery of 9-desglycinamide, 8- arginine vasopressin
was examined in an in-vitro intestinal loop model and reported that stability of
peptide increased significantly.
 Immunological applications of niosomes For studying the nature of the immune
response provoked by antigens niosomes have been used.
 Niosomes have been reported as potent adjuvant in terms of immunological
selectivity, low toxicity and stability

41. Application of Niosome
Targeting of bioactive agents
To reticulo-endothelial system (RES)
 The vesicles occupy preferentially to the cells of RES. It is due to circulating serum factors
known as opsonins, which mark them for clearance.
 Such localized drug accumulation has, however, been exploited in treatment of animal
tumours known to metastasize to the liver and spleen and in parasitic infestation of liver.
To organs other than reticulo-endothelial system(RES)
 By use of antibodies, carrier system can be directed to specific sites in the body.
Immunoglobulins seem to have affection to the lipid surface, thus providing a convenient
means for targeting of drug carrier.
 Many cells have the intrinsic ability to recognize and bind particular carbohydrate
determinants and this property can be used to direct carriers system to particular cells.

42. • Niosomes provide incorporating the drug into for a better targeting of
the drug at appropriate tissue destination .
• They presents a structure similar to liposome and hence they can
represent alternative vesicular systems with respect to liposomes
• 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.
Summary of Niosomes