1. NNIIOOSSOOMMEESS

2. IINNTTRROODDUUCCTTIIOONN::
• Niosomes are novel drug delivery systems in which medication is
encapsulated in a vesicle.
• Niosomes are non-ionic surfactant based uni or multilamellar vesicles
in which an aqueous solute is entirely enclosed by a membrane which
is formed by surfactant macromolecules as bilayers.
• They are very small and microscopic in size. Their size lies in
nanometric scale.
• A diverse range of materials have been used to form niosomes such as
alkyl ethers, alkyl esters, amides, fatty acids and amino acid
compounds.

3. • They are vesicular systems similar to liposomes in which bilayer is
made up of phospholipids and they can be used as carriers of
amphiphilic and lipophilic drugs
• The niosome is made of a surfactant bilayer with its hydrophilic ends
exposed on the outside and inside of the vesicle, while the
hydrophobic chains face each other within the bilayer.
Hydrophobic
chains
Hydrophilic
cavity

4. • Cholesterol when incorporated in bilayer, alters the bilayer
characteristics.

5. ADVANTAGES:
 High patient compliance.
 Osmotically active and stable, as well as they increase the stability of
entrapped drug.
 The vesicles can act as a depot to release the drug slowly and offer a
controlled release.
 Can increase the oral bioavailability of drugs
 Can enhance the skin penetration of drugs
 The surfactants are biodegradable, biocompatible, and non-immunogenic.

6. DISADVANTAGES:
 Physical instability
 Aggregation
 Fusion
 Leaking of entrapped drug
 Hydrolysis of encapsulated drugs which limits the shelf life of the
dispersion.

7. COMPARISON OF NIOSOMES Vs
LIPOSOMES
 Niosomes has certain advantages over liposomes.
 Liposomes face problems such as – they are expensive, their
ingredients like phospholipids are chemically unstable due to their
predisposition to oxidative degradation, they require special storage
and handling and purity of natural phospholipids is variable.
 Niosomes do not have any of these problems as they are made of
uncharged single-chain surfactant molecules compared to liposomes.
 Niosomes behave in-vivo like liposomes, prolonging the circulation of
entrapped drug and altering its organ distribution and metabolic
stability.
 Like liposomes, the properties of niosomes depends both on the
composition of the bilayer and method of their production.

8. TTYYPPEESS OOFF NNIIOOSSOOMMEESS
Based on the vesicle size, niosomes are divided into 3
groups-
Small Unilamellar vesicles (SUV, size 0.025-0.05 μm)
Multilamellar vesicles(MLV, size > 0.05 μm)
Large Unilamellar vesicles (MUV, size > 0.1 μm)

9. METHODS OF PREPARATION
Preparation of Small unilamellar vesicles
Preparation of Multilamellar vesicles
Preparation of Large unilamellar vesicles
Miscellaneous

10. PREPARATION OF SUVs:
SONICATION:
• In this aliquot of drug solution in buffer is added to 150 μmol of
surfactant/cholesterol mixture in a 10ml glass vial.
• The mixture is probe sonicated at 60°C for 3 minutes using a sonicator
with a titanium probe to yield niosomes.
• Probe sonicator- when the sample volume is small.
• Bath sonicator- when the sample volume is large.
• Care must be taken while working with temperature sensitive solute.

11. PREPARATION OF MLVs:
HAND SHAKING METHOD (Thin film hydration technique):
• The surfactant and cholesterol mixture is dissolved in 10 ml of
volatile organic solvent (diethyl ether, chloroform or methanol) in a
round bottom flask.
• The organic solvent is evaporated 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 by gentle agitation.

12. PREPARATION OF LUVs:
REVERSE PHASE EVAPORATION:
• Surfactant is dissolved in chloroform and emulsified with 0.25 vol of
phosphate saline buffer to get a W/O emulsion.
• The mixture is then sonicated and subsequently chloroform is
evaporated under reduced pressure.
• The lipid or surfactant forms a gel first and subsequently hydrates to
form vesicles.
• Free drug (unentrapped) is generally removed by dialysis.

13. ETHER INJECTION:
• In this, slow injection of surfactant:cholesterol solution in ether (20ml)
through a 14 gauge needle at approximately 0.25 ml/min into a pre-heated
aqueous phase maintained at 60°C.
• This forms large vesicles due to vaporization of solvent resulting in
ether gradient extending towards the ether-water interface. It results in
the formation of a bilayer sheet, which eventually folds on itself to
form sealed vesicles.
• In case of thermo labile drugs, fluorinated hydrocarbons are used
incase of ether.

14. MISCELLANEOUS:
MULTIPLE MEMBRANE EXTRUSION METHOD:
• Mixture of surfactant, cholesterol and dicetyl 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 series upto 8 passages.
• It is a good method for controlling niosome size.

15. BUBBLE METHOD:
• It is a novel technique for the 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 are 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) at 70°C, the dispersion mixed for 15 seconds with high shear
homogenizer and immediately “bubbled” at 70°C using nitrogen gas.

16. FORMATION FROM PRONIOSOMES:
• To create proniosomes, a water soluble carrier such as sorbitol is first
coated with the surfactant.
• The coating is done by preparing a solution of the surfactant and
cholesterol in a volatile organic solvent, which is sprayed onto the
powder of sorbitol kept in a rotary evaporator.
• The evaporation of the organic solvent yields a thin coat on the
sorbitol particles.
• The niosomes can be prepared from the proniosomes by adding the
aqueous phase with the drug to the proniosomes with brief agitation
at a temperature greater than the mean transition phase temperature of
the surfactant.

18. SEPARATION OF FREE DRUG
The removal of unentrapped solute from vesicles include various
techniques like –
 DIALYSIS - The aqueous niosomal dispersion is dialyzed in a dialysis
tubing against phosphate buffer or normal saline or glucose solution.
 GEL FILTRATION - The unentrapped drug is removed from niosomal
dispersion through a Sephadex-G-50 column and eluted with
phosphate buffered saline or normal saline.
 CENTRIFUGATION - The niosomal suspension is centrifuged and the
supernatant is separated. The pellet is washed and then re-suspended
to obtain a niosomal suspension free from unentrapped drug.

19. CCHHAARRAACCTTEERRIIZZAATTIIOONN OOFF NNIIOOSSOOMMEESS
SIZE, SHAPE AND MORPHOLOGY:
• Freeze Fracture Electron Microscopy - visualizes the vesicular
structure of surfactant based vesicles.
• Photon Correlation spectroscopy, Ultracentrifugation - determine
mean diameter of the vesicles.
• Electron Microscopy - morphological studies of vesicles.
• Freeze thawing - keeping vesicle suspension at -20°C for 24 hrs
and then heating to ambient temperature increases the vesicle
diameter, which result in fusion of vesicles during the cycle.
VESICULAR SURFACE CHARGE:
• It is determined by measuring the electrophoretic mobility and is
expressed in terms of Zeta potential.

20. ENTRAPMENT EFFICIENCY:
After preparing niosomal dispersion, unentrapped drug is separated
by dialysis and the entrapped drug in niosomes is determined by
complete vesicle disruption using 50% n-propanol or 0.1% Triton X-
100 and the resultant solution is analysed by appropriate assay
method for the drug.
IN VITRO STUDIES:
A method of in vitro release study includes the use of dialysis
tubing. A dialysis sac is washed and soaked in distilled water. The
vesicle suspension is pipetted into a bag made up of the tubing and is
sealed. The bag containing the vesicles is placed in 200 ml 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 method.

21. APPLICATIONS
In the treatment of Lieshmaniasis:
Niosomes are used for drug targeting in treatment of diseases
in which the organism resides in the RES. Lieshmaniasis is a disease
in which parasite invades the cells of liver and spleen. Niosomes are
used for the delivery of stilbogluconate, an anti-leishmaniasis agent to
visceral organs.
In Oncology:
Various anticancer drugs like MTX, DOX can be encapsulated
inside the niosomes and they can be easily delivered to the tumor cells
due to small size.
As a carrier for Haemoglobin
In the delivery of peptide drugs

22. As immunological adjuvants:
The ability of niosomes to enhance antibody production in
response to Bovine Serum Albumin (BSA)was compared with
Freund’s complete adjuvant in the BALB/c mouse which revealed
niosomes as potent stimulator of cellular immunity.
In transdermal drug delivery:
They have application in topical and transdermal products
both containing hydrophobic and hydrophilic drugs. An increase in
the penetration rate is achieved by transdermal delivery incorporated
in niosomes. The intracellular route is the main route of vesicle
penetration across the skin. Ex: erythromycin
In diagnostic imaging:
Niosomes can act as carriers for radiopharmaceuticals
and site specific vehicles for spleen and liver imaging.

23. REFERENCES
Vyas S.P. , Khar R.K. ,Targeted & Controlled Drug
Delivery, Novel Carrier Systems, CBS
Publication,2002,Page No.249-276.
Malhotra M. and Jain N.K. Niosomes as Drug
Carriers.,Indian Drugs 1994, Page No: 81-86.
www.pharmainfo.net
www.sciencedirect.com
www.pharmatutor.org

24. Thank you