Aerosols and propellants MCQs With Answer

Aerosols and propellants MCQs With Answer

by

Aerosols and propellants MCQs With Answer

This collection of MCQs is designed for M.Pharm students studying Molecular Pharmaceutics (MPH 201T) who need a focused review of aerosols and propellants. The questions cover fundamentals and applied aspects: aerosol science, propellant chemistry and selection, formulation types (solution vs suspension), valve and actuator mechanics, filling methods, particle size and aerodynamic behavior, inhalation device performance, environmental regulations and safety. Each question tests conceptual understanding and practical implications encountered in formulation development and quality control. Answers are provided to help self-assess and identify areas needing deeper study, supporting exam preparation and practical formulation decision-making in respiratory drug delivery.

Q1. Which of the following best defines the term “aerosol” in pharmaceutical delivery?

  • A colloidal suspension of macromolecules in water
  • A system of solid or liquid particles dispersed in a gas
  • A liquid emulsion stabilized by surfactants
  • A gas dissolved in a liquefied propellant

Correct Answer: A system of solid or liquid particles dispersed in a gas

Q2. Which property of a propellant most directly determines the driving force for aerosol discharge from a pressurized container?

  • Viscosity
  • Boiling point at atmospheric pressure
  • Vapor pressure at storage temperature
  • Surface tension

Correct Answer: Vapor pressure at storage temperature

Q3. Hydrofluoroalkanes (HFAs) replaced chlorofluorocarbons (CFCs) primarily because:

  • HFAs are less dense than CFCs
  • HFAs have superior solvent power for all drugs
  • HFAs do not deplete the ozone layer
  • HFAs are non-flammable at any concentration

Correct Answer: HFAs do not deplete the ozone layer

Q4. In a pressurized metered-dose inhaler (pMDI), what is the primary function of the metering valve?

  • To convert liquid drug into fine particles
  • To deliver a reproducible volume of formulation per actuation
  • To maintain container pressure by releasing propellant
  • To filter particulates from the formulation

Correct Answer: To deliver a reproducible volume of formulation per actuation

Q5. Which formulation type is most likely to show sedimentation and require suspension stability control in pMDIs?

  • Solution formulation in HFA
  • Semi-solid gel formulation
  • Suspension formulation of micronized drug
  • Dry powder in a DPI device

Correct Answer: Suspension formulation of micronized drug

Q6. The aerodynamic diameter of aerosol particles is most important because it determines:

  • Container pressure during storage
  • Deposition site in the respiratory tract
  • Chemical stability of the drug
  • Rate of propellant evaporation

Correct Answer: Deposition site in the respiratory tract

Q7. Which of the following is a common cosolvent used in HFA solution pMDIs to dissolve lipophilic drugs?

  • Glycerol
  • Ethanol
  • Propylene glycol
  • Polysorbate 80

Correct Answer: Ethanol

Q8. What is the main environmental regulation that led to global phase-out of CFC propellants?

  • REACH Regulation
  • MONTREAL PROTOCOL on Substances that Deplete the Ozone Layer
  • Kyoto Protocol on greenhouse gases
  • FDA Drug Master File requirements

Correct Answer: MONTREAL PROTOCOL on Substances that Deplete the Ozone Layer

Q9. Which filling method for pMDIs involves cooling the propellant below its boiling point so it can be liquid-filled and then sealed?

  • Room-temperature pressure-filling
  • Cold filling (also called liquid filling)
  • Underhead filling
  • Two-stage metering

Correct Answer: Cold filling (also called liquid filling)

Q10. In an HFA suspension pMDI, which excipient is commonly used to reduce aggregation of suspended particles?

  • Lactose monohydrate
  • Magnesium stearate
  • Fluorinated surfactants or polyvinylpyrrolidone
  • Polyethylene glycol 4000

Correct Answer: Fluorinated surfactants or polyvinylpyrrolidone

Q11. The term “saturated vapor pressure” for a volatile propellant refers to:

  • The pressure required to compress the propellant in the can
  • The equilibrium pressure of vapor above the liquid at a given temperature
  • The minimum pressure needed to actuate the valve
  • The partial pressure of air dissolved in the formulation

Correct Answer: The equilibrium pressure of vapor above the liquid at a given temperature

Q12. In cascade impactor testing, which parameter is primarily measured to evaluate pMDI performance?

  • Flame point of propellant
  • Mass median aerodynamic diameter (MMAD) and fine particle fraction
  • Bulk density of the formulation
  • Valve leak rate

Correct Answer: Mass median aerodynamic diameter (MMAD) and fine particle fraction

Q13. Which hazard is particularly associated with some hydrocarbon propellants (e.g., n-butane, propane)?

  • Ozone depletion
  • Flammability and explosion risk
  • High toxicity by inhalation at ppm levels
  • Polymerization with common drugs

Correct Answer: Flammability and explosion risk

Q14. Which statement correctly contrasts HFA-134a and HFA-227ea propellants?

  • HFA-134a has higher molecular weight and lower vapor pressure than HFA-227ea
  • HFA-227ea generally provides lower vapor pressure and slower plume expansion than HFA-134a
  • HFA-134a is solid at room temperature while HFA-227ea is liquid
  • Both have identical solvent power for organic drugs

Correct Answer: HFA-227ea generally provides lower vapor pressure and slower plume expansion than HFA-134a

Q15. The presence of ethanol in an HFA solution pMDI will generally:

  • Decrease vapor pressure of the headspace dramatically
  • Increase solubility of lipophilic drug and modify vapor-liquid equilibrium
  • Act as a propellant and increase delivery force
  • Eliminate the need for a metering valve

Correct Answer: Increase solubility of lipophilic drug and modify vapor-liquid equilibrium

Q16. Which factor most strongly affects plume geometry and initial droplet size from a pMDI actuator?

  • Ambient humidity only
  • Actuator orifice diameter and valve discharge velocity
  • Color of the actuator cap
  • Type of secondary packaging

Correct Answer: Actuator orifice diameter and valve discharge velocity

Q17. A suspension pMDI shows progressively reduced emitted dose over repeated actuations while can pressure remains constant. The most likely cause is:

  • Propellant leakage from valve
  • Drug agglomeration and valve blockage or adhesion to container walls
  • Evaporation of solvent leading to supersaturation
  • Change in ambient temperature only

Correct Answer: Drug agglomeration and valve blockage or adhesion to container walls

Q18. Which device would be most suitable for delivering high doses of saline solution to the lower respiratory tract in a hospital setting?

  • pMDI
  • Dry powder inhaler (DPI)
  • Jet or ultrasonic nebulizer
  • Transdermal patch

Correct Answer: Jet or ultrasonic nebulizer

Q19. Which material is commonly used for canisters to ensure chemical compatibility with HFA propellants and formulations?

  • Polyethylene terephthalate (PET) plastic
  • Aluminum with internal surface coating or stainless steel
  • Glass with cork stopper
  • Unlined mild steel

Correct Answer: Aluminum with internal surface coating or stainless steel

Q20. In formulation development, the “pressure-filling” method differs from “cold-filling” because:

  • Pressure-filling introduces propellant as vapor at room temperature while cold-filling fills liquid propellant at reduced temperature
  • Pressure-filling uses vacuum to remove dissolved gases only
  • Cold-filling is used exclusively for DPI devices
  • Pressure-filling results in lower container pressure than cold-filling

Correct Answer: Pressure-filling introduces propellant as vapor at room temperature while cold-filling fills liquid propellant at reduced temperature

Leave a Comment