Lecture 3 Flashcards
What are DPIs?
inspirationally flow driven inhalers
Main advantage of DPI over pMDI
More environmentally friendly
Define aerosolisation
converting a dry powder into an aerosol
Define fluidisation
Where the flow of air starts to separate particles from one another
What is the purpose of meshes?
the swirling of air separates the small particles from large ones
Define fine particle fraction (FPF)
the percentage that reaches your lungs
What three factors affect FPF?
Inhaler device, patient inspiratory flow and powder formulation
Why do you want to create turbulence within the inhaler?
To increase de-agglomeration so more drug is delivered to the lungs
What are the different types of DPI devices?
Single-unit dose (disposable), Single uni dose (reusable), Multi-unit dose, multi-unit dose (reservoir)
What is the issue with powder formulations of small particles?
They stick together
Name the three inter particulate adhesion forces
Van de Waals Forces, Electrostatic forces, Capillary forces
Define van de waals forces
the fine attractive force between all atoms
short-range force
dominant at low humidity in absence of electrostatic forces
Define capillary forces
increases humidity
water helps to where particles together
dominant under ambient conditions
more frequent if the surface is less hydrophobic
Define electrostatic forces
Caused by friction contact
long-range force, attractive or repulsive
more dominant at low humidity
What factors influence the three forces and alter adhesion forces?
Particle size
Particle shape
Surface roughness
Surface chemistry
Humidity
