Inhaled Drug Delivery

Question 1

What determines inhaled drug delivery?

Answer 1

patient, device, formulation

Question 2

List 5 deposition mechanisms

Answer 2

• Inertial impaction
• Sedimentation
• Brownian motion
• Interception
• Electrostatic precipitation

Question 3

Describe inertial impaction

Answer 3

when airflow changes direction particles continue in the original direction

Question 4

Describe sedimentation

Answer 4

due to gravity

Question 5

Describe brownian motion

Answer 5

small particles randomly hit colloidal particles by molecules/atom of medium

Question 6

Describe interception

Answer 6

dimensions of particles and lung tubes

Question 7

Describe electrostatic precipitation

Answer 7

charged aerosol particles are attracted to oppositely charged surfaces influencing direction of flow

Question 8

List 3 particle properties that affect inhaled drug delivery

Answer 8

• Solubility
• Hygroscopicity
• Size

Question 9

What size should inhaled particles be and why?

Answer 9

<5 micro-moles for deep lung deposition

Question 10

State how patient handling affects inhaled drug delivery

Answer 10

inhaler technique

Question 11

State and describe 4 aerosol properties that affect inhaled drug delivery.

Answer 11

• Velocity - high V leads to inertial impaction at bends.
• Size range
• Conc - higher conc increases particle interaction
• Evaporation of propellants - residual propellant may increase effective particle size increasing chance of reaction - cough reflex

Question 12

List 4 physiological properties that affect inhaled drug delivery

Answer 12

• Nature of lungs - lung bifurcation
• Mechanisms keeping particles out e.g. cough
• Diseased lungs e.g. asthma
• Drugs forced to change direction