inhalation workshop Flashcards
what factors can be changed for a dry powder inhaler?
density diameter shape charge of particles chemical characterisitcs
what factors can be changed for a liquid aerosol inhaler?
propellant
viscosity
particle size
size distribution
what kind of solvent propellants do pMDIs use?
non-polar e.g. HFA
what kind of propellants do DPIs use?
lol trick question, none
what kind of solvent do nebulisers use?
polar e.g. water
majority of particles from pMDIs and DPIs deposit where?
in upper airways by sedimentation and impaction
how can you increase sedimentation rate
decreased air velocity so hold ur breath
how do ultrasonic nebulisers work?
increase liquid SA by increasing energy
ultrasound–> kinetic energy
ultrasound focused by piezoelectrical transducers
intense agitation at focus –> conical fountain above liquid which is dispersed to aerosol
large particles removed by impaction
how do vibrating mesh ultrasonic nebulisers work?
as piezo expands and contracts from alternating voltage, the mesh is pulled back and thrown forward
with every forward thrust, mono-disperse fine droplets are ejected
smaller aerodynamic diameter, the …
better
what kind of inhalation should you do for pMDIs compared to DPIs?
pMDI: slow and deep
DPIs: fast and deep (to mobilise the particles)
how can you decrease aerodynamic diameter?
- reduce size
- reduce density
- increase shape factor e.g. elongation
what factors of the drug can affect AD?
- crystallinity, produces polymorphs of different sizes
2. particles are hygroscopic and lungs are humid, so leads to absorption and aggregation of particles
what excipients used in DPIs?
none really but If you want…
- lactose - highly crystalline and smooth surface
- lipids
