Pulmonary Drug Delivery Flashcards
Pulmonary drug delivery is for (local/systemic) therapy
local
Why is pulmonary drug delivery accomplished via airways?
- Big surface area
2. Ease of accessibility
Does the pulmonary drug delivery avoid first pass effect?
It does (renal), but the lung itself has some metabolic capability so the benefit is neglibigle
What is found within the upper respiratory tract?
- Nose
- Throat
- Pharynx
- Larynx
What is found within the lower respiratory tract?
- Trachea
- Bronchi
- Bronchioles
- Alveoli
What are the two regions of the lower respiratory tract?
- Conducting
2. Respiratory
What is found within the conducting region?
Trachea to terminal bronchioles
What is found within the respiratory region?
Respiratory bronchioles + alveolar region
What are the conducting airways lined with?
Ciliated epithelial cells
If an insoluble particle is deposited on these airways, what happens?
Trapped by mucus
Swept upwards
Either expelled via exhalation or swallowed
How are most drugs absorbed?
Passive diffusion
What is the rate limiting barrier of drugs into the blood?
Epithelium
Is there systemic absorption?
There is, but very small. Goal = local effect
(Ionized/unionized) form is the preferred way to pulmonary absorption
Unionized
How could you slow the absorption rate?
Use suspension formulation, powders of less water soluble salts, or novel drug delivery systems (liposomes)
Can drugs accumulate in the lungs?
Yes
(Acidic/Basic) drugs usually accumulate in the lung
Basic
What size of aerosols typically deposit in the upper respiratory tract? How is it removed?
> 5micrometers
Muco-ciliary clearance
Where is cilia found?
Trachea to terminal bronchioles
Do alveoli have cilia?
Nope
How does the alveoli remove foreign particles?
They have phagocytic cells; uses lymphatic + circulatory systems
What are the three main mechanisms for particle deposition in the lung?
- Inertial impaction
- Gravitational sedimentation
- Diffusion
Describe Inertial Impaction
High momentum particles will impact on airway walls
Describe Gravitational Sedimentation
Particles move due to gravity
Dependent on size and density
Uses Stokes’ Law
Describe Diffusion
Brownian Motion
Main mechanism for small particles
Diffusion is inversely proportional to particle size
For MDIs, does the pressure inside container always stay consistent?
Yes
What are some disadvantages of pMDIs?
Inefficient at drug delivery
Droplets exit at high velocity and drug is lost thru impaction
What is the most common problem w/ pulmonary deliveries?
Incorrect use by pts
What is the advantage of Dry Powder Inhalers (DPIs)?
- Propellant free
2. Can deliver more drug than pMDIs
What are some disadvantages of DPIs?
- Aggregated materials wont reach lower regions of lung
2. Drug delivery is less efficient than pMDIs
What are some advantages of Nebulizers?
- Useful for pt who have difficulty w/ pMDIs + DPIs
2. You can just breath normally
What are some disadvantages of Nebulizers?
- Poorly efficient; material released into environment
What kind of Nebulizer CANT deliver suspensions, liposomes, etc?
Ultrasonic
