Pharmaceutics (aerosols) Flashcards
What is the physical role of the airways?
Heat and humidity air
Filter air taken in
Clear deposited particles into GIT
How are particles cleared in the upper and lower airway region?
Ciliary moves mucus up towards pharynx where is it swallowed into GiT
No cilia or mucus layer so insoluble particles take long to be cleared by macrophages or surface tension effects whereas soluble get absorbed into blood stream
What is an aerosol?
Suspension of a liquid or solid in a gas
What 5 mechanisms causing deposition in the respiratory tract?
Inertial impaction Sedimentation Diffusion Interception Electrostatic precipitation
Which particles are effected by inertial impaction?
Heavier ones have more inertia so deposit in upper airways
Which particles are effected by sedimentation?
Large particles effected by gravity
Why deliver drugs to the lungs?
Local effect Systemic effect Rapid onset of action Smaller dose than oral forms Less GI and systemic side effects More comfortable
Which particles are effected by the brownian diffusion?
Smaller particles which leave the flow lines
How are particles effected by interception?
Don’t deviate from air flow lines however as tubes get smaller the particles come in contact with tract due to size and shape
How are particles effected by electrostatic deposition?
Charged particles attracted to airway or particles repeal each other and come into contact with airways
Define respirable fraction
Percentage of drug present in aerosol particles less than 5 micromoles in size and hence deposited
What imaging techniques can be used to determine particle size of inhaled products?
Microscopy (optical and electron)
Laser diffraction
Aerosizer
What 4 main apparatuses are used in impaction methods?
Twin liquid impinger
Andersen cascade impactor
Multistage liquid impinger
Next generation impactor
Which particles are effected by the brownian diffusion?
Smaller particles which leave the flow lines
How are particles effected by interception?
Don’t deviate from air flow lines however as tubes get smaller the particles come in contact with tract due to size and shape
