Quality control of aerosols is a critical subject for B.Pharm students focused on ensuring safe and effective pulmonary and topical drug delivery. This introduction covers aerosol dosage forms, pressurized metered-dose inhalers (pMDIs), dry powder inhalers (DPIs), and nebulizers, emphasizing tests like aerodynamic particle size distribution, delivered dose uniformity, spray pattern, plume geometry, content assay, leak testing, and container-closure integrity. Understanding instrumentation (cascade impactors, laser diffraction), acceptance criteria from pharmacopeias (USP/IP), and factors affecting stability (propellants, preservatives, formulation excipients) is essential for product development and regulatory compliance. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary purpose of aerodynamic particle size distribution (APSD) testing for inhalation aerosols?
- To determine chemical stability of the drug in formulation
- To measure the mass of formulation remaining in the canister
- To assess particle sizes that determine lung deposition
- To evaluate microbial contamination
Correct Answer: To assess particle sizes that determine lung deposition
Q2. Which instrument is considered the pharmacopeial standard for cascade impactor testing of aerosols?
- Laser diffraction particle size analyzer
- Next Generation Impactor (NGI)
- Scanning electron microscope
- Gas chromatograph
Correct Answer: Next Generation Impactor (NGI)
Q3. Delivered dose uniformity (DDU) testing evaluates which parameter?
- Amount of drug emitted from the device per actuation
- Viscosity of the formulation
- Particle shape under electron microscopy
- Container-closure color stability
Correct Answer: Amount of drug emitted from the device per actuation
Q4. Which propellant replaced CFCs due to environmental regulations and is commonly used in pMDIs?
- Chlorofluorocarbon (CFC-12)
- Hydrofluoroalkane (HFA-134a)
- Nitrous oxide
- Carbon dioxide
Correct Answer: Hydrofluoroalkane (HFA-134a)
Q5. What does fine particle fraction (FPF) represent in aerosol characterization?
- Percentage of particles larger than 10 µm
- Percentage of emitted dose as particles below a cutoff (e.g., 5 µm)
- Total residual mass in the device
- Viscosity-related aerosol spread
Correct Answer: Percentage of emitted dose as particles below a cutoff (e.g., 5 µm)
Q6. Which test assesses uniform distribution of active ingredient across multiple actuations?
- Spray pattern test
- Content uniformity or dose content uniformity test
- Leak detection by helium
- Plume geometry measurement
Correct Answer: Content uniformity or dose content uniformity test
Q7. In pMDI design, what is the role of the metering chamber in the valve?
- To heat the propellant
- To measure and dispense a reproducible dose per actuation
- To filter particles above 10 µm
- To sterilize the formulation before emission
Correct Answer: To measure and dispense a reproducible dose per actuation
Q8. Which parameter is directly measured by a spray pattern test using paper capture?
- Aerodynamic particle size
- Distribution and symmetry of spray deposition
- Chemical potency of drug
- Valve leakage rate
Correct Answer: Distribution and symmetry of spray deposition
Q9. What is the significance of priming a pMDI before initial use?
- To sterilize the canister
- To ensure correct dose metering and reproducible spray performance
- To remove drug residues from the actuator
- To increase particle size for lower lung deposition
Correct Answer: To ensure correct dose metering and reproducible spray performance
Q10. Which parameter is most relevant to predict central versus peripheral lung deposition?
- Tapped density of powder
- Aerodynamic particle size (MMAD)
- pH of formulation
- Valve stem length
Correct Answer: Aerodynamic particle size (MMAD)
Q11. Which test is used to detect container-closure leakage in pressurized aerosols?
- Flame ionization detector
- Dye ingress test or helium leak detection
- Optical rotation
- Viscometry
Correct Answer: Dye ingress test or helium leak detection
Q12. What does emitted dose (ED) differ from delivered dose (DD) primarily by?
- Chemical degradation during storage
- Losses in actuator and mouthpiece before patient
- Residual solvent content
- Particle crystallinity
Correct Answer: Losses in actuator and mouthpiece before patient
Q13. Which excipient class is often used to improve dispersion and reduce particle agglomeration in DPIs?
- Preservatives
- Carrier particles like lactose
- Antifoaming agents
- Heavy metal salts
Correct Answer: Carrier particles like lactose
Q14. According to pharmacopeial guidelines, what is the typical cut-off aerodynamic diameter for lung-depositing fraction?
- >20 µm
- <10 µm only
- Approximately ≤5 µm
- Exactly 1 µm
Correct Answer: Approximately ≤5 µm
Q15. Which property of a pMDI valve influences reproducibility of dose release?
- Color of actuator
- Metering chamber volume and tolerance
- Container printing method
- Propellant boiling point only
Correct Answer: Metering chamber volume and tolerance
Q16. What is the purpose of oxygen or moisture barrier considerations in aerosol packaging?
- To increase aerodynamic diameter
- To prevent formulation degradation and maintain stability
- To change propellant chemical identity
- To improve taste of inhaled drug
Correct Answer: To prevent formulation degradation and maintain stability
Q17. Which in vitro test best correlates with regional lung deposition for regulatory submissions?
- Assay by UV alone
- Cascade impactor aerodynamic profiling (e.g., NGI) with MMAD and FPF
- Colorimetric pH test
- Visual inspection of canister
Correct Answer: Cascade impactor aerodynamic profiling (e.g., NGI) with MMAD and FPF
Q18. For microbial control of nebulizer formulations, which property is most critical?
- Viscosity only
- Use of preservatives and aseptic manufacturing to control contamination
- Particle shape
- Valve metering accuracy
Correct Answer: Use of preservatives and aseptic manufacturing to control contamination
Q19. What is residual volume in the context of aerosols?
- Volume of propellant vapor above liquid
- Amount of formulation remaining in the device after actuations
- Volume of actuator channel
- Headspace oxygen volume specified by pharmacopeia
Correct Answer: Amount of formulation remaining in the device after actuations
Q20. Which factor does NOT significantly affect aerosol particle size in pMDIs?
- Nozzle orifice diameter
- Actuation force and velocity
- Formulation viscosity and surfactants
- Label color of the canister
Correct Answer: Label color of the canister
Q21. What is the rationale for using a spacer with a pMDI in clinical use?
- To increase propellant boiling point
- To reduce oropharyngeal deposition and improve lung delivery
- To sterilize the aerosol plume
- To decrease the drug potency
Correct Answer: To reduce oropharyngeal deposition and improve lung delivery
Q22. Which regulatory document provides methods and acceptance criteria for inhalation aerosols?
- ICH Q8 only
- USP chapters and monographs, and IP standards
- Food labeling regulations
- CFR Title 21 unrelated sections
Correct Answer: USP chapters and monographs, and IP standards
Q23. Which analytical technique is commonly used to quantify aerosolized drug in impactor stages?
- Atomic absorption spectroscopy
- High-performance liquid chromatography (HPLC)
- Thermogravimetric analysis
- Polarimetry
Correct Answer: High-performance liquid chromatography (HPLC)
Q24. What does plume geometry testing measure for a pMDI?
- Chemical assay concentration
- Spatial dispersion pattern and angle of emitted plume
- Sterility of the product
- Container-closure weight
Correct Answer: Spatial dispersion pattern and angle of emitted plume
Q25. Why is dose counter accuracy important in inhaler devices?
- It affects aesthetic appeal only
- It informs patients and clinicians about remaining usable doses for safety and adherence
- It increases propellant efficiency
- It sterilizes the actuator
Correct Answer: It informs patients and clinicians about remaining usable doses for safety and adherence
Q26. Which of the following is a common challenge when formulating biologics for nebulization?
- Achieving adequate flavor masking
- Maintaining protein stability against shear and air–liquid interface stress
- Color matching with device housing
- Reducing pMDI metering tolerance
Correct Answer: Maintaining protein stability against shear and air–liquid interface stress
Q27. In dose uniformity sampling, why are initial and end of life (EOL) checks required?
- To measure color change only
- To ensure consistent dosing throughout product life, including start-up and depletion phases
- To increase residual volume intentionally
- To test microbial resistance
Correct Answer: To ensure consistent dosing throughout product life, including start-up and depletion phases
Q28. What effect does high formulation viscosity have on aerosol performance for nebulizers?
- Improves valve metering for pMDIs
- May reduce aerosol generation efficiency and alter droplet size
- Automatically sterilizes the formulation
- Increases fine particle fraction for DPIs
Correct Answer: May reduce aerosol generation efficiency and alter droplet size
Q29. Which test evaluates the chemical stability of the drug in the aerosol during shelf life?
- Spray pattern only
- Stability studies including assay, degradation products, and potency over time
- Plume geometry only
- Visual inspection of packaging fonts
Correct Answer: Stability studies including assay, degradation products, and potency over time
Q30. For a DPI, which device characteristic most directly affects patient inspiratory effort requirement?
- Valve metering chamber
- Device airflow resistance
- Label adhesive type
- Propellant type
Correct Answer: Device airflow resistance
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