Types of aerosol systems MCQs With Answer provides B. Pharm students a focused, practical review of aerosol drug delivery, formulation components, device design, and performance evaluation. This resource covers pressurized metered-dose inhalers (pMDIs), dry powder inhalers (DPIs), nebulizers (jet, ultrasonic, mesh), propellants (CFCs, HFA), valves, actuators, particle size (MMAD), deposition mechanisms, dose uniformity, and stability issues. Emphasis is on formulation challenges, device–drug compatibility, characterization techniques (cascade impactor, laser diffraction), and clinical performance factors like inspiratory flow and humidification. The questions strengthen conceptual understanding and exam readiness with application-level scenarios. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which component in a pressurized metered-dose inhaler (pMDI) is primarily responsible for delivering a reproducible dose?
- Actuator mouthpiece shape
- Metering chamber
- Propellant boiling point
- Canister material
Correct Answer: Metering chamber
Q2. Which propellant replaced CFCs in modern pMDIs due to environmental concerns?
- Hydrofluoroalkane (HFA)
- Chlorofluorocarbon (CFC)
- Carbon dioxide (CO2)
- Nitrogen gas (N2)
Correct Answer: Hydrofluoroalkane (HFA)
Q3. For dry powder inhalers (DPIs), which factor most strongly influences the emitted fine particle fraction?
- Patient inspiratory flow rate
- Canister orientation
- Propellant vapor pressure
- Valve spring tension
Correct Answer: Patient inspiratory flow rate
Q4. Mass median aerodynamic diameter (MMAD) of aerosol particles around 1–5 µm is ideal for deposition in which region?
- Nasal cavity
- Alveolar and lower airways
- Oropharynx only
- Stomach after swallowing
Correct Answer: Alveolar and lower airways
Q5. Which mechanism dominates deposition of particles smaller than 0.5 µm in the respiratory tract?
- Inertial impaction
- Gravitational sedimentation
- Brownian diffusion
- Electrostatic attraction
Correct Answer: Brownian diffusion
Q6. A spacer attached to a pMDI primarily helps to:
- Increase propellant vapor pressure
- Improve coordination and reduce oropharyngeal deposition
- Sterilize the aerosol plume
- Enhance drug chemical stability
Correct Answer: Improve coordination and reduce oropharyngeal deposition
Q7. Which aerosol device generates droplets by forcing liquid through a vibrating mesh?
- Jet nebulizer
- Ultrasonic nebulizer
- Mesh nebulizer
- Pressurized nasal spray
Correct Answer: Mesh nebulizer
Q8. In aerosol characterization, which instrument separates particles based on aerodynamic diameter by inertial impaction?
- Cascade impactor
- Scanning electron microscope (SEM)
- High-performance liquid chromatograph (HPLC)
- Thermogravimetric analyzer (TGA)
Correct Answer: Cascade impactor
Q9. Which excipient in pMDI formulations acts as a surfactant to improve suspension stability?
- Polysorbate 80
- Sodium chloride
- Cellulose acetate
- Magnesium stearate
Correct Answer: Polysorbate 80
Q10. Which property of powder formulations is critical for DPI performance to ensure deagglomeration?
- Particle hygroscopicity only
- Interparticulate cohesion and dispersibility
- Thermal conductivity
- Color stability
Correct Answer: Interparticulate cohesion and dispersibility
Q11. Which deposition mechanism is most important for particles depositing in the large central airways during high flow inhalation?
- Diffusion
- Gravitational settling
- Inertial impaction
- Chemical reaction
Correct Answer: Inertial impaction
Q12. Which factor does NOT typically affect emitted dose from a pMDI?
- Actuation technique
- Storage temperature extremes
- Ambient barometric pressure only
- Valve metering accuracy
Correct Answer: Ambient barometric pressure only
Q13. Which aerosol type is most suitable for delivering large-volume saline or antibiotic solutions for nebulization?
- pMDI
- DPI
- Jet nebulizer
- Nasal spray pump
Correct Answer: Jet nebulizer
Q14. What is the main advantage of hydrofluoroalkane (HFA) propellants over CFCs besides environmental benefit?
- They are more corrosive
- Allow formulation of suspensions and solutions with improved aerosol performance
- They freeze at body temperature
- Reduce need for valves
Correct Answer: Allow formulation of suspensions and solutions with improved aerosol performance
Q15. Which test measures aerodynamic particle size distribution for regulatory submission of inhalation products?
- pH titration
- Cascade impaction with MMAD determination
- Viscosity measurement
- Melting point determination
Correct Answer: Cascade impaction with MMAD determination
Q16. Which design feature of a DPI reduces sensitivity to ambient humidity?
- Hydrophilic carrier particles
- Breath-actuated dose protection and moisture-resistant blister packaging
- Open powder reservoir
- Use of volatile propellants
Correct Answer: Breath-actuated dose protection and moisture-resistant blister packaging
Q17. Which statement about ultrasonic nebulizers is correct?
- They are ideal for suspensions because high frequency has no effect on particles
- They can heat the formulation and may degrade heat-sensitive drugs
- They always produce larger droplets than jet nebulizers
- They use propellant gases to create aerosols
Correct Answer: They can heat the formulation and may degrade heat-sensitive drugs
Q18. Which metric describes the portion of emitted aerosol likely to deposit in the lungs (typically <5 µm)?
- Emitted dose
- Fine particle dose (or fine particle fraction)
- Total organic carbon
- Bulk density
Correct Answer: Fine particle dose (or fine particle fraction)
Q19. Which issue is a common formulation challenge for suspension pMDIs?
- Complete solubility of active in propellant
- Particle sedimentation and dose variability
- Excessive foaming in the mouth
- Inability to fill the canister
Correct Answer: Particle sedimentation and dose variability
Q20. What is the primary function of the actuator in an aerosol canister?
- Generate propellant gas
- Open and direct the aerosol plume and influence plume characteristics
- Determine chemical stability of drug
- Heat the formulation before inhalation
Correct Answer: Open and direct the aerosol plume and influence plume characteristics
Q21. Which factor most directly influences the residence time of aerosol particles in the airways due to sedimentation?
- Particle aerodynamic diameter
- Color of the formulation
- Type of canister metal
- Labeling instructions
Correct Answer: Particle aerodynamic diameter
Q22. Which test assesses dose uniformity over the life of a metered-dose inhaler?
- Leakage current test
- Content uniformity over actuations (dose content uniformity test)
- Microbial limit test
- DSC thermal analysis
Correct Answer: Content uniformity over actuations (dose content uniformity test)
Q23. Which device would be least dependent on patient inspiratory effort for drug delivery?
- Dry powder inhaler
- Breath-actuated DPI
- Nebulizer with external compressor
- Single-dose capsule DPI
Correct Answer: Nebulizer with external compressor
Q24. Which cause can lead to corrosion of metal canisters in aerosol products?
- Presence of residual moisture and reactive formulation components
- Use of nitrogen as headspace gas only
- Low solubility of the drug in propellant
- Proper addition of anti-corrosion coatings
Correct Answer: Presence of residual moisture and reactive formulation components
Q25. Which of the following best defines emitted dose?
- Mass of drug remaining in canister after use
- Mass of drug delivered from the device during actuation
- Mass of propellant per actuation
- Volume of headspace gas
Correct Answer: Mass of drug delivered from the device during actuation
Q26. Electrostatic charge in plastic spacers can cause which problem?
- Increased chemical degradation of drug
- Enhanced deposition of drug onto spacer walls, reducing delivered dose
- Spontaneous ignition of propellant
- Immediate neutralization of propellant pressure
Correct Answer: Enhanced deposition of drug onto spacer walls, reducing delivered dose
Q27. Which carrier particle is commonly used in DPI formulations to improve flow and dose metering?
- Lactose monohydrate
- Polystyrene beads
- Iron filings
- Magnesium oxide
Correct Answer: Lactose monohydrate
Q28. Which parameter is most critical when designing an inhalation therapy for deep lung deposition?
- Tablet hardness
- Aerodynamic particle size distribution centered around 1–3 µm MMAD
- Packaging color
- Propellant odor
Correct Answer: Aerodynamic particle size distribution centered around 1–3 µm MMAD
Q29. In a suspension pMDI, which processing step is important to ensure uniform drug distribution?
- Continuous shaking during storage only
- Proper milling or micronization to achieve uniform particle size and controlled suspension
- Adding large abrasive particles
- Heating above boiling point of propellant
Correct Answer: Proper milling or micronization to achieve uniform particle size and controlled suspension
Q30. Which regulatory concern is often evaluated for nasal aerosol sprays in addition to particle size?
- Tablet disintegration time
- Spray pattern, plume geometry, and droplet size distribution
- Presence of metallic taste
- Solid-state polymorphism only
Correct Answer: Spray pattern, plume geometry, and droplet size distribution
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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