Evaluation of pharmaceutical aerosols MCQs With Answer

Evaluation of pharmaceutical aerosols MCQs With Answer

Evaluation of pharmaceutical aerosols is essential for ensuring safe, effective inhalation therapies. This collection of MCQs with answers helps B. Pharm students master aerosol characterization, particle size distribution, aerodynamic diameter, fine particle fraction, emitted dose, delivered dose, cascade impaction, NGI, Andersen impactor, laser diffraction, plume geometry, spray pattern, propellant chemistry, metering valves, and device performance testing. Questions emphasize principles of aerosol physics, deposition mechanisms (impaction, sedimentation, diffusion), method validation, USP requirements, and practical troubleshooting of pMDIs, DPIs, and nebulizers. Designed for exam preparation and concept reinforcement, these MCQs promote critical thinking and practical knowledge for pharmaceutical aerosol evaluation. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the definition of aerodynamic diameter?

• Geometric diameter of a particle measured by microscopy
• Diameter of a unit-density sphere with the same settling velocity as the particle
• Diameter measured using electrical mobility
• Average diameter of particles in a polydisperse aerosol

Correct Answer: Diameter of a unit-density sphere with the same settling velocity as the particle

Q2. Which instrument is commonly used to determine mass median aerodynamic diameter (MMAD)?

• Laser diffraction analyzer
• Cascade impactor (e.g., NGI)
• Dynamic light scattering
• Scanning electron microscope

Correct Answer: Cascade impactor (e.g., NGI)

Q3. Fine particle fraction (FPF) refers to which of the following?

• Percentage of particles >10 µm
• Percentage of emitted dose in the respirable size range (usually <5 µm)
• Ratio of delivered dose to label claim
• Mass of drug retained in the actuator

Correct Answer: Percentage of emitted dose in the respirable size range (usually <5 µm)

Q4. Which deposition mechanism predominates for particles around 1–5 µm in the small airways?

• Inertial impaction
• Brownian diffusion
• Gravitational sedimentation
• Electrostatic attraction

Correct Answer: Gravitational sedimentation

Q5. Which propellant replaced CFCs in modern pMDIs due to environmental regulations?

• Chlorofluorocarbon (CFC-12)
• Hydrofluoroalkane (HFA-134a or HFA-227)
• Carbon tetrachloride
• Nitrous oxide

Correct Answer: Hydrofluoroalkane (HFA-134a or HFA-227)

Q6. Emitted dose is defined as:

• The dose retained in the metering valve
• The mass of drug leaving the device during actuation
• The dose deposited in the deep lung
• The label claim on the product

Correct Answer: The mass of drug leaving the device during actuation

Q7. Delivered dose typically refers to:

• The amount of drug leaving the mouthpiece and available to the patient
• The total drug in the canister
• The amount retained in the spacer
• The dose measured by spectroscopy

Correct Answer: The amount of drug leaving the mouthpiece and available to the patient

Q8. Which USP apparatus is commonly used for nebulizer performance testing?

• USP Apparatus 2 (paddle)
• Next Generation Impactor (NGI) and cascade impactors or impingers such as USP 3
• Rotating drum
• High performance liquid chromatograph

Correct Answer: Next Generation Impactor (NGI) and cascade impactors or impingers such as USP 3

Q9. What parameter does the geometric standard deviation (GSD) describe?

• Mean particle chemical composition
• Polydispersity or spread of the aerodynamic size distribution
• Shape irregularity of particles
• Density variation within particles

Correct Answer: Polydispersity or spread of the aerodynamic size distribution

Q10. Which factor least affects aerosol deposition in the lungs?

• Particle aerodynamic diameter
• Patient inhalation flow rate
• Ambient room temperature (within normal ranges)
• Particle hygroscopicity

Correct Answer: Ambient room temperature (within normal ranges)

Q11. The role of a spacer device with a pMDI is to:

• Increase aerosol particle size
• Reduce velocity, improve coordination, and increase lung deposition of fine particles
• Convert propellant to powder
• Filter out respirable particles

Correct Answer: Reduce velocity, improve coordination, and increase lung deposition of fine particles

Q12. Laser diffraction provides which primary measurement for aerosols?

• Aerodynamic diameter and MMAD directly
• Equivalent volume or geometric particle size distribution
• Chemical composition of the drug
• Valve life cycles

Correct Answer: Equivalent volume or geometric particle size distribution

Q13. During cascade impaction, which property primarily determines on which stage a particle deposits?

• Chemical solubility
• Aerodynamic diameter and inertia
• Color of the formulation
• Electrical conductivity

Correct Answer: Aerodynamic diameter and inertia

Q14. What is the significance of the Mass Median Aerodynamic Diameter (MMAD)?

• It indicates the diameter at which 50% of particle number is below
• It indicates the aerodynamic diameter below which 50% of the aerosol mass resides
• It measures the geometric mean of particle density
• It defines the maximum particle size emitted

Correct Answer: It indicates the aerodynamic diameter below which 50% of the aerosol mass resides

Q15. Which inhaler type relies primarily on patient inspiratory flow to disperse powder?

• Pressurized metered dose inhaler (pMDI)
• Dry powder inhaler (DPI)
• Jet nebulizer
• Soft mist inhaler

Correct Answer: Dry powder inhaler (DPI)

Q16. A high fine particle dose with low emitted dose indicates which problem?

• Efficient lung delivery with low total drug emitted
• Device malfunction retaining most drug in canister
• Excessive propellant flow
• Contamination of formulation

Correct Answer: Device malfunction retaining most drug in canister

Q17. Which is a primary advantage of NGI over older cascade impactors?

• It measures chemical purity directly
• It provides better stage cut-off precision and is suitable for modern inhaler flows
• It requires no calibration
• It uses optical sizing for each stage

Correct Answer: It provides better stage cut-off precision and is suitable for modern inhaler flows

Q18. Hygroscopic growth of aerosol particles in the respiratory tract leads to:

• Decrease in aerodynamic diameter
• Growth in particle size, potentially increasing deposition by sedimentation or impaction
• Immediate chemical degradation
• Conversion to gas phase

Correct Answer: Growth in particle size, potentially increasing deposition by sedimentation or impaction

Q19. Which parameter is most directly measured in a spray pattern or plume geometry test?

• Particle chemical composition
• Spatial distribution and angle/width of aerosol plume
• Canister internal pressure
• Propellant boiling point

Correct Answer: Spatial distribution and angle/width of aerosol plume

Q20. For method validation of aerosol testing, which attribute is essential?

• Color consistency of the formulation
• Accuracy, precision, specificity, and robustness
• Number of marketing approvals
• Storage in amber bottles only

Correct Answer: Accuracy, precision, specificity, and robustness

Q21. Which respiratory deposition mechanism is most important for submicron (<0.5 µm) particles?

• Inertial impaction
• Gravitational sedimentation
• Brownian diffusion
• Electrostatic deposition

Correct Answer: Brownian diffusion

Q22. The shot weight test for pMDIs evaluates:

• The mass of formulation emitted per actuation
• The viscosity of the formulation
• The aerosol color intensity
• The canister wall thickness

Correct Answer: The mass of formulation emitted per actuation

Q23. Metering valve malfunction in a pMDI most directly affects:

• Drug chemical structure
• Consistency of dose delivered per actuation
• Ambient humidity only
• Particle crystallinity

Correct Answer: Consistency of dose delivered per actuation

Q24. Which test assesses the particle mass balance across impactor stages and device?

• Content uniformity test
• Impactor stage mass balance or cascade impactor recovery
• Disintegration test
• Viscosity profiling

Correct Answer: Impactor stage mass balance or cascade impactor recovery

Q25. What is the effect of increasing inspiratory flow rate for a DPI on emitted aerosol?

• Decreased deagglomeration and lower fine particle fraction
• Increased deagglomeration and generally higher fine particle fraction
• No effect on aerosol characteristics
• Immediate drug degradation

Correct Answer: Increased deagglomeration and generally higher fine particle fraction

Q26. Twin-stage impinger (TSI) primarily separates particles by:

• Optical scattering
• Two differential impaction stages representing throat and lung
• Electrical mobility
• Magnetic properties

Correct Answer: Two differential impaction stages representing throat and lung

Q27. In aerodynamic sizing, particle density influences which property?

• Only chemical potency
• Aerodynamic diameter because it depends on geometric diameter and particle density
• Only color and taste
• Evaporation rate only

Correct Answer: Aerodynamic diameter because it depends on geometric diameter and particle density

Q28. Which USP chapter deals specifically with aerosol testing methods for inhalation products?

• USP General Chapter None
• USP General Chapter 601 (or relevant inhalation product chapters depending on edition)
• USP chapter on ophthalmic products
• USP chapter on parenterals only

Correct Answer: USP General Chapter 601 (or relevant inhalation product chapters depending on edition)

Q29. What is the main purpose of leak testing for pressurized inhaler canisters?

• To measure aerodynamic diameter
• To ensure container closure integrity and avoid loss of propellant or contamination
• To calibrate the cascade impactor
• To change the chemical composition of the drug

Correct Answer: To ensure container closure integrity and avoid loss of propellant or contamination

Q30. Which corrective action is appropriate if cascade impactor recovery is low and inconsistent?

• Ignore results and proceed to release
• Investigate system losses, check actuator alignment, verify sampling flow rate, and validate recovery procedures
• Increase label claim without investigation
• Change the drug formulation blindly

Correct Answer: Investigate system losses, check actuator alignment, verify sampling flow rate, and validate recovery procedures

G S Sachin

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.

Mail- Sachin@pharmacyfreak.com