Flashcards in Inhaled Route Deck (16)
What kind of conditions requires inhaled drug delivery?
airway diseases like asthma
Advantages of inhaled route: (4)
- smaller doses can be used - reduces side effects and costs
- rapid absorption (large surface area, high vascular surface, thin air-blood barrier)
- avoids harsh GI environment and degradation
- avoids hepatic first-pass metabolism
Disadvantages of inhaled route: (4)
- complex delivery devices meaning high costs
- aerosol devices can be difficult to use
- mucus layer limits absorption, mucociliary clearance reduces retention time
- local side effects
Inhaltion drug delivery requires the formulation to be...
What is a pharmaceutical aerosol?
two-phase system of solid particles or liquid droplets dispersed in the air. Very small size particles
The fate of particles in the airways (3)
Patient factors affecting particle deposition: (2)
breathing patterns - the larger the inhaled volume, the greater the peripheral distribution of particles
lung physiology e.g. lung capacity / diseases
Phsyicochemical factors affecting particle deposition:
the aerodynamic size of the drug particle (which depends on physical size and density)
Shape and physical stability of particles
3 main mechanisms responsible for drug deposition:
There is an upper size and lower size limit effective for...
drug deposition in the lung
An aerosolised drug powder must first dissolve in the...
mucus layer before absorption
once in, it will diffuse through the mucus layer and enter the aqueous environment of the epithelial lining liquid
How are particles deposited in the ciliated conducting airways cleared?
by mucociliary clearance within 24 hours are swallowed with the mucus
Particles deposited into the alveolar region are cleared by...
Drug absorption can only take place if...
dissolution is faster than clearance
How are hydrophobic materials absorbed?
at a rate dependent on their oil/water partition coefficients