Niosomes are a novel drug delivery system comprised of non-ionic surfactants that encapsulate drugs in microscopic vesicles, offering advantages over liposomes in terms of biocompatibility and stability. The formulation process involves selecting appropriate surfactants and hydration mediums, while evaluations include assessment of particle size, zeta potential, and drug entrapment efficiency. Niosomes can be modified for enhanced targeting and stability, and their efficacy can be evaluated through various in vitro and in vivo studies.

1. NIOSOMES: FORMULATION AND
EVALUATION
SUBMITTED BY: PRACHI PANDEY, RAHUL PAL
M. PHARM (PHARMACEUTICS), IIIRD SEM.
DEPARTMENT OF PHARMACEUTICS, NIMS INSTITUTE OF PHARMACY, NIMS UNIVERSITY, JAIPUR,
RAJASTHAN, 303121, INDIA.

2. INTRODUCTION
 Niosomes are a novel drug delivery system that encapsulates the medication in a
vesicular system made up of non ionic surfactants.
 In 1909, Paul Ehrlich named niosomes as “magic bullet” as he proposed the
strategies of targeted drug delivery system without damaging the surrounding cells.
 The vesicle is made up of a bilayer of non-ionic surfactants, thus the name niosomes.
 Niosomes are extremely small and microscopic (on a nanometric scale).
 Despite having a similar structure to liposomes, they have several advantages over
them.
 Niosomes are biocompatible, non-immunogenic, and biodegradable in nature and
exhibit flexibility in their structured characterization
Niosomes

3. INTRODUCTION
 The main purpose of developing vesicular structures are
modification of distribution profiles and targeted delivery of the drug
 Based on the vesicle size, niosomes can be divided into three
groups.
I. Small unilamellar vesicles (SUV, size=0.025-0.05 μm),
II. Multilamellar vesicles (MLV, size=>0.05 μm), and
III. Large unilamellar vesicles (LUV, size=>0.10 μm).
Niosomes

4. LIPOSOMES V/S NIOSOMES
Feature Niosomes Liposomes
Composition
Uncharged single-chain surfactants and
cholesterol
Double-chain phospholipids (neutral or charged)
and cholesterol
Cost Cheaper More expensive
Preparation Easier, less specific process Complex, requires specific phospholipids
Stability Highly stable Can be less stable
Permeability
Higher permeability for ions and small
molecules
Lower permeability
Drug entrapment
efficiency
Can be higher Can be lower
Targeted delivery Potential for targeting with specific surfactants
Potential for targeting with specific
phospholipids
Commercial availability Limited More widely available
Examples of use
Topical drug delivery, gene delivery, cosmetic
applications
Drug delivery, cosmetics, vaccines

5. COMPOSITIONS OF NIOSOMES
Component Function
Non-ionic Surfactant
Forms the bilayer membrane, affecting permeability and drug
entrapment.
Cholesterol Stabilizes the membrane, influencing fluidity and targeting ability.
Hydrating Medium Provides the internal environment for encapsulated drugs.
Charge Molecule Improves stability, targeting, and sometimes drug release.

6. COMPOSITIONS OF NIOSOMES
Component Examples Required
Non-ionic surfactant
Span 60, Span 20, Tween 80, Tween
20, Pluronic F127, Cremophor EL,
Solutol HS15
Yes
Cholesterol
Yes, Optional, Optional, Optional,
Optional, Optional, Optional
As per the need
Hydrating medium
Water, Buffered solution (e.g., PBS),
Alcohol/water mixture, Organic
solvents (e.g., ethanol, methanol),
Ionic solutions
Yes
Charge molecule
None (neutral niosomes),
Dicetylphosphate (anionic),
Stearylamine (cationic),
Phosphatidylglycerol (anionic),
Chitosan (cationic)
Optional

7. NIOSOMES ENCAPSULATION

8. NIOSOMES ENCAPSULATION
 In the formulation of niosomes, the selection of surfactants is based on hydrophilic-lipophilic balance
(HLB) value. HLB values between 4 and 8 recommended for the facile formation of niosomes and
surfactants with an HLB value of more than 8 are required to optimize cholesterol concentration.
 However, it has been widely observed that HLB value between 4 and 8 is highly recommended for better
encapsulation efficiency, of niosomes. For example, long stearyl and short lauryl chain length increase
and decrease the entrapment efficiency of niosomes, respectively.
 Long hydrophilic chains result in increased encapsulation of hydrophilic drugs, and long hydrophobic
chains result in improved encapsulation of lipophilic drugs.

9. NON IONIC SURFACTANTS
 Long Hydrophilic Chains and Increased Encapsulation of Hydrophilic Drugs:
 Surfactants with longer hydrophilic chains create larger aqueous compartments within the niosome
bilayer. This provides more space for water-soluble drugs to reside, leading to higher encapsulation
efficiency.
 Example: Span 60 (HLB 4.7) has a longer hydrophilic chain compared to Span 20 (HLB 8.6). Studies
have shown that using Span 60 in niosomes resulted in significantly higher encapsulation efficiency of
the hydrophilic drug gentamicin, compared to formulations using Span 20.

10. NON IONIC SURFACTANTS
 Long Hydrophobic Chains and Improved Encapsulation of Lipophilic Drugs:
 Long hydrophobic chains increase the affinity of the niosome bilayer for lipid-soluble drugs. These
drugs can partition and entrap themselves within the bilayer structure, leading to improved
encapsulation.
 Example: Tween 80 (HLB 15) has a longer hydrophobic chain compared to Tween 20 (HLB 16.7).
Niosomes prepared with Tween 80 demonstrated superior encapsulation of the lipophilic drug
curcumin compared to those made with Tween 20.

11. CHARGE INDUCERS
 In niosomes, which are microscopic spheres used for drug delivery, charge inducers offer several benefits.
They primarily improve the stability of the niosomes by introducing a positive or negative charge on their
surface. This charge creates a repulsive force between individual niosomes, preventing them from
clumping together and compromising the formulation. Additionally, a higher zeta potential (a measure of
the charge) indicates greater stability. This enhanced stability ensures efficient transport and delivery of
the encapsulated drug to its target site.

12. CHARGE INDUCERS
 Negative charge inducers
 Enhances stability by preventing aggregation; May be useful for targeting niosomes to positively charged
cells; Can help to reduce interaction with serum proteins
 Example: Dicetyl phosphate, dihexadecyl phosphate, and lipoamino acid
 Positive charge inducers
 Enhances stability by preventing aggregation; Can be used to target niosomes to negatively charged cells;
May promote drug release in acidic environments
 Example: Stearylamine and cetylpridinium chloride, help to stabilize the vesicles.

13. HYDRATION MEDIUM
 The hydration medium used during the formation of niosomes plays a crucial role in determining their
characteristics and performance. Depending on the choice of hydration medium, niosomes can exhibit
varied drug encapsulation efficiency, particle size, and stability. For instance, the use of phosphate buffer
saline (PBS) as a hydration medium can result in the formation of small-sized niosomes with high
encapsulation efficiency, making them suitable for the delivery of hydrophilic drugs such as doxorubicin
or 5-fluorouracil, which require high entrapment efficiencies for effective therapeutic outcomes. On the
other hand, employing ethanol as a hydration medium can lead to the formation of larger niosomes with
improved stability and prolonged drug release profiles, making them ideal for the delivery of lipophilic
drugs like paclitaxel or curcumin, where sustained release is desired to maintain therapeutic
concentrations over an extended period.

14. HYDRATION MEDIUM
 The hydration medium used during the formation of niosomes plays a crucial role in determining their
characteristics and performance. Depending on the choice of hydration medium, niosomes can exhibit
varied drug encapsulation efficiency, particle size, and stability. For instance, the use of phosphate buffer
saline (PBS) as a hydration medium can result in the formation of small-sized niosomes with high
encapsulation efficiency, making them suitable for the delivery of hydrophilic drugs such as doxorubicin
or 5-fluorouracil, which require high entrapment efficiencies for effective therapeutic outcomes. On the
other hand, employing ethanol as a hydration medium can lead to the formation of larger niosomes with
improved stability and prolonged drug release profiles, making them ideal for the delivery of lipophilic
drugs like paclitaxel or curcumin, where sustained release is desired to maintain therapeutic
concentrations over an extended period.

15. MODIFICATIONS IN NIOSOME

16. PEGYLATION
 Pegylation is a process where polyethylene glycol (PEG), a biocompatible and hydrophilic polymer, is attached to the surface of
niosomes. This modification offers several advantages for drug delivery:
 Benefits of Pegylation:
 Increased Stability: PEG creates a steric barrier, preventing proteins and other molecules in the blood from adhering to the niosome surface. This
reduces aggregation and opsonization (recognition by immune cells), leading to a longer circulation time in the bloodstream.
 Improved Bioavailability: Enhanced stability means more niosomes reach the target site, delivering their cargo.
 Reduced Toxicity: PEG is generally non-toxic and non-immunogenic, minimizing potential side effects.
 Enhanced Targeting: Specific ligands (molecules that bind to receptors) can be attached to PEG, enabling niosomes to target specific cells or tissues.
 Methods of Pegylation:
 Pre-conjugated Surfactants: Surfactants with pre-attached PEG chains can be incorporated into the niosome bilayer.
 Post-insertion Methods: PEG molecules can be chemically linked to the existing niosomal surface after preparation.

17. OPSONISATION
 Opsonization is a crucial process in the body's immune system where molecules called opsonins coat foreign particles, like niosomes,
making them more recognizable and palatable for phagocytes like macrophages. These phagocytes then engulf and eliminate the foreign
particles. In the context of niosomes, opsonization can have both positive and negative impacts:
 Positive Impacts:
 Enhanced Clearance: Opsonization can actually be beneficial for niosomes designed for short-term drug delivery. It facilitates rapid uptake by
phagocytes, leading to efficient drug release at the target site. This can be useful for drugs requiring prompt action or localization within specific tissues.
 Stimulating Immune Response: In some cases, niosomes can be intentionally designed to induce a controlled immune response, particularly for vaccines or
immunotherapies. Opsonization helps antigen-presenting cells recognize and process the encapsulated antigens, ultimately leading to a stronger immune
response.
 Negative Impacts:
 Reduced Circulation Time: For niosomes meant for sustained or targeted drug delivery, opsonization can be detrimental. Rapid clearance by phagocytes
reduces their circulation time, hindering their ability to reach the target site and release the drug effectively. This can limit the overall therapeutic efficacy.
 Potential Immune Reactions: In some individuals, excessive opsonization can trigger unwanted immune reactions, particularly for niosomes carrying large
or immunogenic payloads. This can lead to inflammation, allergic reactions, or even organ damage.

18. STEALTH
 Stealth, also known as long-circulating properties, is a crucial aspect of niosome design for efficient drug delivery. It refers to the
ability of niosomes to evade the body's natural defense mechanisms, namely the mononuclear phagocyte system (MPS), for an
extended period in the bloodstream. This allows them to circulate longer, accumulate at the target site more effectively, and
ultimately deliver the encapsulated drug with greater potency.
 Niosomes achieve stealth properties:
 Steric Repulsion: The primary strategy involves attaching polyethylene glycol (PEG) molecules to the niosome surface. PEG
forms a hydrophilic "cloud" around the niosome, creating a steric barrier. This barrier repels proteins in the blood plasma that
would otherwise opsonize (mark) the niosome for uptake by macrophages, the key players in the MPS.
 Reduced Protein Adsorption: PEGylation also minimizes the direct interaction between niosomes and plasma proteins. This
further reduces opsonization and subsequent clearance by the MPS.
 Tailored Charge: Modifying the surface charge of niosomes can also contribute to stealth. A slightly negative charge, for
example, can repel negatively charged cell membranes of macrophages, making them less likely to engulf the niosome.

19. NIOSOMAL FORMULATION
 Niosomal formulation can be followed by these following process
1. Thin-film hydration method,
2. Ether injection method,
3. Reverse-phase evaporation method,
4. Transmembrane pH gradient drug uptake process,
5. Bubble method, and
6. Micro-fluidization method

20. THIN FILM HYDRATION METHOD
a. Dissolve drug, non-ionic surfactant(s), and cholesterol in a volatile organic solvent (e.g., chloroform, methanol).
b. Remove the solvent using a rotary evaporator, forming a thin film on the flask wall.
c. Hydrate the film with an aqueous phase (buffer, saline) under gentle agitation.
d. Optionally, apply sonication or homogenization to improve dispersion.
e. Separate unentrapped drug by centrifugation or ultrafiltration.
f. Size and entrapment efficiency can be optimized by varying ingredients and processing parameters.
 Advantages: Simple, versatile, suitable for various drugs.
 Disadvantages: May have low encapsulation efficiency, possibility of residual solvent.
THIN FILM HYDRATION
METHOD

21. ETHER INJECTION METHOD
a. Dissolve drug in a water-miscible organic solvent (e.g., diethyl ether).
b. Inject the organic phase containing drug into a heated aqueous phase containing surfactant and cholesterol.
c. Rapid diffusion and solvent evaporation induce niosome formation.
d. Remove residual solvent by dialysis or ultrafiltration.
 Advantages: High encapsulation efficiency, rapid process.
 Disadvantages: Limited solvent choice, potential drug instability due to high temperatures.
ETHER INJECTION METHOD

22. REVERSE PHASE EVAPORATION METHOD
a. Dissolve drug, surfactant(s), and cholesterol in an organic phase.
b. Add an aqueous phase containing a helper lipid (e.g., dicetylphosphate).
c. Evaporate the organic phase under reduced pressure.
d. Niosomes form spontaneously due to micelle-to-vesicle transition.
e. Remove helper lipid by ultrafiltration if needed.
 Advantages: High encapsulation efficiency, good control over size and stability.
 Disadvantages: Requires helper lipid, potential for drug-lipid interactions.
REVERSE PHASE
EVAPORATION METHOD

23. TRANSMEMBRANE PH GRADIENT DRUG UPTAKE
PROCESS
a. Load niosomes with a pH-sensitive drug in an acidic environment.
b. Raise the external pH using a buffered solution.
c. The drug ionizes and becomes trapped within the niosomal core.
d. Remove free drug by ultrafiltration.
 Advantages: Targeted drug delivery, high encapsulation efficiency for ionizable drugs.
 Disadvantages: Complex process, limited to ionizable drugs.
Transmembrane pH Gradient
Drug Uptake Process

24. BUBBLE METHOD
 Dissolve drug, surfactant(s), and cholesterol in an organic phase.
 Sparge the solution with gas (e.g., nitrogen) to form microbubbles.
 Add an aqueous phase and continue sparging.
 Solvent evaporation and shear stress from bubbles induce niosome formation.
 Separate niosomes by centrifugation or ultrafiltration.
 Advantages: Continuous process, high scalability, potential for large-scale production.
 Disadvantages: Complex setup, control over size and encapsulation efficiency might be challenging.
BUBBLE METHOD

25. MICRO FLUIDIZED METHOD
a. Mix drug, surfactant(s), and cholesterol in an aqueous phase.
b. Subject the mixture to high pressure and shear stress in a microfluidic device.
c. The intense forces disrupt and reform vesicles, generating niosomes.
d. Optimize pressure and flow rate for desired size and distribution.
 Advantages: Narrow size distribution, high entrapment efficiency, continuous process.
 Disadvantages: Requires specialized equipment, high initial investment.
MICRO FLUIDIZED
METHOD

26. EVALUATION
IN-VITRO
 Particle size and size distribution: DLS, NTA
 Zeta potential: Zetameter
 Polydispersity index (PDI): Calculated from size
distribution data
 Morphology: TEM, SEM
 Entrapment efficiency: Separation of free and
encapsulated drug
 In vitro release: Simulated dissolution studies in relevant
media
 Stability studies: Monitoring changes in size, zeta
potential, etc., over time
 Cytotoxicity studies: Evaluation of potential toxicity on
cell lines.
IN-VIVO
 Biodistribution studies: Tracking niosomal
distribution in organs and tissues
 Pharmacokinetic studies: Monitoring drug
concentration in blood and plasma over time
 Target site accumulation: Assessing targeting
efficiency to specific tissues or cells
 Therapeutic efficacy studies: Evaluating the drug's
therapeutic effect in animal models
 Toxicity studies: Assessing potential side effects in
animals.

27. EVALUATION (IN VITRO)
Parameter Description Accepted Limit Instrument Formula
Particle size
Average diameter of
niosomes
< 500 nm (optimal)
Dynamic Light
Scattering (DLS)
D = K1 * λ / θ Where: D = diameter, K1
= proportionality constant, λ =
wavelength of light, θ = scattering angle
Zeta potential
Surface charge of
niosomes
± 30 mV (absolute
value)
Zeta potential analyzer
ζ = (μ ε / η) * V Where:ζ = zeta potential,
μ = electrophoretic mobility, ε =
dielectric constant of medium, η =
viscosity of medium, V = electric field
strength
Polydispersity
index (PDI)
Size distribution of
niosomes
0.1 - 0.3 (narrow
distribution)
DLS
PDI = σ² / D² Where: σ² = variance of
particle size distribution
Morphology
Shape and surface
characteristics of
niosomes
Spherical, smooth
surface
Transmission Electron
Microscopy (TEM) or
Scanning Electron
Microscopy (SEM)
Image analysis software to measure size,
shape, and surface features
Entrapment
efficacy
Percentage of drug
encapsulated within
niosomes
> 50% (desired)
Spectrophotometry,
HPLC, other drug-
specific methods
% Entrapment = (Encapsulated drug /
Total drug) * 100

28. EVALUATION (IN VIVO)
Drug Category Desired Goal Animal Model Techniques Employed Outcome Measures
Antibiotics
Improved efficacy,
reduced side effects,
targeted delivery
Mice, rats
Tail vein injection,
subcutaneous injection,
oral gavage
Bacterial burden reduction,
survival rates, blood drug
levels, tissue distribution,
histopathology
Anticancer drugs
Enhanced
bioavailability,
improved tumor
targeting, reduced
systemic exposure
Mice, rats
Intravenous injection,
intratumoral injection
Tumor growth inhibition,
survival rates, blood drug
levels, tumor drug
accumulation, biodistribution
studies
Vaccines
Increased
immunogenicity and
protection
Mice, rabbits
Intramuscular injection,
subcutaneous injection
Antibody response, protection
against pathogen challenge,
immune cell activation
Gene therapy
Efficient gene delivery
to target tissues
Mice, rats
Intravenous injection,
local injection
Transgene expression levels,
functional analysis of expressed
protein, biodistribution studies

29. APPLICATION OF NIOSOMES
 Drug Delivery: Niosomes can encapsulate various drugs, enhancing their bioavailability, stability, and targeted
delivery. They show potential in treating:
 Skin disorders: Topical niosomal formulations for antifungal (e.g., clotrimazole), anti-inflammatory
(e.g., diclofenac), and anti-acne (e.g., isotretinoin) drugs are being explored and marketed
(e.g., Vesigel®, Diflucan®).
 Ophthalmic diseases: Niosomal formulations offer sustained and targeted drug delivery to the eye, potentially
improving treatment of glaucoma, dry eye, and infections.
 Cancer therapy: Niosomes can deliver anticancer drugs directly to tumor cells, reducing systemic side
effects. Research is ongoing, with some formulations reaching clinical trials.
 Cosmetics: Niosomes are incorporated into various cosmetic products like sunscreens, moisturizers, and anti-
aging creams due to their ability to encapsulate and deliver various ingredients effectively.

30. FUTURE ASPECTS OF NIOSOMES
 Targeted Drug Delivery: Niosomes can be further modified with specific ligands or antibodies to
target specific cells or tissues, improving efficacy and reducing side effects.
 Combination Therapy: Combining niosomes with other drug delivery systems or therapeutic agents
could offer synergistic effects for complex diseases.
 Controlled Release: Modifying niosomal composition can achieve controlled and sustained release of
drugs, improving patient compliance and therapeutic outcomes.
 Gene Therapy: Niosomes are being explored as potential carriers for genetic material, offering a novel
approach for gene therapy.
 Personalized Medicine: Tailoring niosomal formulations to individual patients based on their genetic
makeup and disease characteristics holds great promise for personalized medicine.

31. REFERENCES
1) Okore, V.C., Attama, A.A., Ofokansi, K.C., Esimone, C.O. and Onuigbo, E.B., 2011.
Formulation and evaluation of niosomes. Indian journal of pharmaceutical
sciences, 73(3), p.323.
2) Srinivas, S., Kumar, Y.A., Hemanth, A. and Anitha, M., 2010. Preparation and evaluation
of niosomes containing aceclofenac. Dig J Nanomater Bios, 5(1), pp.249-254.