Introduction
Niosomes are vesicular carriers composed primarily of non-ionic surfactants and cholesterol that form bilayer structures capable of encapsulating hydrophilic and lipophilic drugs. Understanding niosome composition, methods of preparation (thin-film hydration, reverse-phase evaporation, ether injection, microfluidization, proniosomes) and critical factors affecting entrapment efficiency, particle size, zeta potential, and stability is essential for formulation development. Characterization techniques such as TEM, DSC, FTIR and in vitro release testing inform optimization. Niosomes enable controlled release, targeted delivery, reduced toxicity and improved bioavailability across routes (oral, topical, parenteral). This concise guide focuses on practical formulation and application points for B.Pharm students. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What are the primary components required to form a niosome?
- Phospholipid and cholesterol
- Non-ionic surfactant and cholesterol
- Polymeric surfactant and bile salts
- Peptide and polysaccharide
Correct Answer: Non-ionic surfactant and cholesterol
Q2. Which non-ionic surfactant is commonly used in niosome formulation?
- Span 60 (sorbitan monostearate)
- Sodium dodecyl sulfate (SDS)
- Lysozyme
- Poloxamer 407 only
Correct Answer: Span 60 (sorbitan monostearate)
Q3. Which preparation method involves formation of a thin surfactant film followed by hydration?
- Reverse-phase evaporation
- Thin-film hydration (hand-shaking)
- Ether injection
- Microemulsion dilution
Correct Answer: Thin-film hydration (hand-shaking)
Q4. Which factor most directly increases bilayer rigidity and decreases leakage in niosomes?
- High hydrophilic-lipophilic balance (HLB) surfactant
- Increased cholesterol content
- Low surfactant concentration
- Use of ionic surfactant
Correct Answer: Increased cholesterol content
Q5. Entrapment efficiency of a hydrophilic drug in niosomes primarily depends on which parameter?
- Surfactant alkyl chain length and vesicle lamellarity
- Color of the surfactant
- Presence of peptides only
- External humidity exclusively
Correct Answer: Surfactant alkyl chain length and vesicle lamellarity
Q6. Which characterization technique provides information about thermal transitions and drug–bilayer interactions?
- Transmission electron microscopy (TEM)
- Differential scanning calorimetry (DSC)
- Dynamic light scattering (DLS)
- UV–visible spectroscopy
Correct Answer: Differential scanning calorimetry (DSC)
Q7. A high zeta potential (positive or negative) in niosomes indicates which property?
- Low drug loading
- Improved physical stability due to electrostatic repulsion
- Immediate drug release
- High tendency for aggregation
Correct Answer: Improved physical stability due to electrostatic repulsion
Q8. Which method is effective for producing small and uniform niosomes suitable for parenteral use?
- Hand-shaken thin-film only
- Microfluidization or extrusion
- Simple mixing at room temperature
- Direct cryogenic freezing
Correct Answer: Microfluidization or extrusion
Q9. Adding a charge-inducing agent such as dicetyl phosphate to a niosomal formulation primarily influences what?
- Vesicle color
- Surface charge and colloidal stability
- Chemical synthesis of surfactant
- Drug pKa
Correct Answer: Surface charge and colloidal stability
Q10. Reverse-phase evaporation method is particularly advantageous for encapsulating which type of drug?
- Highly volatile gases
- Large hydrophilic molecules and macromolecules
- Only lipophilic steroids
- Inorganic salts exclusively
Correct Answer: Large hydrophilic molecules and macromolecules
Q11. Which parameter is NOT typically measured during niosome characterization?
- Entrapment efficiency
- Particle size distribution
- Tensile strength of free drug crystals
- Zeta potential
Correct Answer: Tensile strength of free drug crystals
Q12. Increasing the surfactant:cholesterol ratio (more surfactant relative to cholesterol) generally results in:
- More rigid bilayer and lower permeability
- Less stable vesicles with increased fluidity
- Complete precipitation of drug
- Formation of micelles only
Correct Answer: Less stable vesicles with increased fluidity
Q13. Proniosomes are advantageous during storage because:
- They are aqueous dispersions needing refrigeration
- They are dry formulations that convert to niosomes on hydration
- They degrade faster than niosomes
- They require immediate use after preparation
Correct Answer: They are dry formulations that convert to niosomes on hydration
Q14. Which route of administration is commonly explored for topical niosomal formulations?
- Intravenous injection only
- Transdermal or dermal application
- Inhalation via dry powder inhaler only
- Ophthalmic drops exclusively
Correct Answer: Transdermal or dermal application
Q15. Which release mechanism is typical for drugs from niosomes?
- Purely enzymatic degradation with no diffusion
- Combination of diffusion through bilayer and vesicle erosion
- Instantaneous burst release with no sustained phase
- Only pH-triggered covalent cleavage
Correct Answer: Combination of diffusion through bilayer and vesicle erosion
Q16. Which analytical technique provides direct visualization of niosome morphology and lamellarity?
- Dynamic light scattering (DLS)
- Transmission electron microscopy (TEM)
- Infrared spectroscopy (FTIR)
- High-performance liquid chromatography (HPLC)
Correct Answer: Transmission electron microscopy (TEM)
Q17. HLB (hydrophilic–lipophilic balance) of a surfactant influences niosome formation because:
- Only HLB > 20 produce bilayers
- Surfactants with low to moderate HLB favor bilayer formation and vesicle stability
- HLB has no effect on vesicle properties
- High HLB always gives higher entrapment of lipophilic drugs
Correct Answer: Surfactants with low to moderate HLB favor bilayer formation and vesicle stability
Q18. PEGylation of niosomes is performed to:
- Increase vesicle aggregation in blood
- Provide steric stabilization and prolong circulation time
- Remove cholesterol from the bilayer
- Convert niosomes to micelles
Correct Answer: Provide steric stabilization and prolong circulation time
Q19. Which statement about drug loading in niosomes is TRUE?
- Lipophilic drugs preferentially partition into the bilayer, hydrophilic drugs into the aqueous core
- Hydrophilic drugs always give 100% entrapment
- Lipophilic drugs cannot be loaded into niosomes
- Entrapment is independent of preparation method
Correct Answer: Lipophilic drugs preferentially partition into the bilayer, hydrophilic drugs into the aqueous core
Q20. Which sterilization method is least suitable for niosomal dispersions intended for parenteral use?
- Sterile filtration through 0.22 µm filter if vesicles are small
- Autoclaving high-temperature steam sterilization
- Gamma irradiation under controlled conditions
- Aseptic preparation and terminal filtration
Correct Answer: Autoclaving high-temperature steam sterilization
Q21. Which excipient can be used to improve stability of niosomes during lyophilization?
- Sodium lauryl sulfate
- Sugars like trehalose or sucrose as cryoprotectants
- Strong acids
- Organic solvents like chloroform added post-lyophilization
Correct Answer: Sugars like trehalose or sucrose as cryoprotectants
Q22. Incorporation of charged lipids into niosomes is primarily used to:
- Neutralize surface and promote aggregation
- Modulate surface charge to prevent aggregation and alter cell interactions
- Make bilayer permeable to large proteins immediately
- Guarantee 100% drug retention indefinitely
Correct Answer: Modulate surface charge to prevent aggregation and alter cell interactions
Q23. Which in vitro method estimates drug release kinetics from niosomes?
- Dialysis bag diffusion method
- Differential scanning calorimetry (DSC)
- Thin-layer chromatography for composition only
- Atomic absorption spectroscopy for metal ions only
Correct Answer: Dialysis bag diffusion method
Q24. Compared to liposomes, niosomes generally offer which advantage?
- Higher cost and lower chemical stability
- Greater chemical stability, lower cost and easier storage
- Inability to carry hydrophilic drugs
- Guaranteed oral bioavailability for all drugs
Correct Answer: Greater chemical stability, lower cost and easier storage
Q25. Which parameter would you adjust to reduce niosome particle size during formulation?
- Decrease energy input during preparation
- Use high-energy methods like sonication or microfluidization
- Increase cholesterol greatly without changing method
- Allow formulation to stand at 4°C for weeks
Correct Answer: Use high-energy methods like sonication or microfluidization
Q26. A polydispersity index (PDI) value close to 0.1 for niosomes indicates:
- Very broad size distribution
- Uniform and narrow size distribution
- Complete instability and aggregation
- Layered crystalline structure
Correct Answer: Uniform and narrow size distribution
Q27. For intracellular targeting of macrophages, which property of niosomes is often exploited?
- Nanometer size and surface properties promoting phagocytosis
- Complete impermeability to cells
- Use of very large micron-sized vesicles only
- Negative effect of cholesterol removal
Correct Answer: Nanometer size and surface properties promoting phagocytosis
Q28. FTIR (Fourier-transform infrared spectroscopy) is used in niosome studies to:
- Measure particle size distribution directly
- Detect possible chemical interactions between drug and excipients
- Sterilize the formulation
- Visualize vesicle lamellarity
Correct Answer: Detect possible chemical interactions between drug and excipients
Q29. Which is a common limitation or challenge in scaling up niosome production?
- Reproducible control of particle size and entrapment efficiency at larger scale
- Impossible to store niosomes at all
- They cannot be characterized analytically
- No regulatory requirements exist
Correct Answer: Reproducible control of particle size and entrapment efficiency at larger scale
Q30. In targeted drug delivery, ligand-conjugated niosomes achieve specificity by:
- Random diffusion only
- Surface attachment of targeting moieties (antibodies, peptides) that bind receptors on target cells
- Increasing cholesterol solely
- Removing surfactant to expose the drug
Correct Answer: Surface attachment of targeting moieties (antibodies, peptides) that bind receptors on target cells
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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