PHAR 5714 FORMULATION EXAM STUDY GUIDE
breathing pattern affect deposition? - ANSWER YES
Upper respiratory tract includes - ANSWER nose
pharynx
larynx
Lower respiratory tract - ANSWER trachea, bronchi, bronchioles, alveoli
airway dimensions - ANSWER from trachea to alveolar sacs - airway diameter
decreases from 1.8cm to 0.04cm
Total surface area of alveolar - ANSWER 140 m2 - large surface area allowed for more
gas exchange
physiology of the lung - ANSWER 1. globet cells produces mucus to trap foreign
particles
2. epithelial cells in conducting airways are ciliated - to transport foreign particles
upwards for elimination
What is an aerosol? - ANSWER A suspension of solid or liquid particles in gas
What are the sites of aerosol particle deposition? - ANSWER 1. at back of throat -
swallowed and useless
2. at bronchioles - good for local treatment eg asthma
3. at alveoli - for systemic absorption
4 factors affecting deposition - ANSWER 1. particle properties: size, shape, charge
2. aerosol particles: concentration, velocity of spray, particle size range
3. respiratory tract properties - disease state, geometry
4. breathing patterns - residence time (breath holding), volumetric flow rate (breathing
rate)
Are all particles the same size in an aerosol? - ANSWER - no, they are polydisperse
- a log-normal distribution
aerodynamic diameters (AED) - ANSWER - particles with same AED can be of different
dimensions and shapes
,3 ways in which particles deposit in airways - ANSWER 1. diffusion
2. sedimentation
3. inertial impaction
diffusion of aerosol - ANSWER - very fine particles (less than 0.5 micron) are deposited
by diffusion
- random movement of particles through the gas (Brownian motion)
- rate is inversely proportion to particle size
sedimentation of aerosol particles - ANSWER - sedimentation due to vertical
gravitational force
- Stoke's law applies: sedimentation rate depends on particle size and density
What is the dominant mechanism for deposition for particles between 0.5 to 5 microns -
ANSWER sedimentation
Inertial impaction - ANSWER - particles carried by a gas stream has its own momentum
- particles can either
1. follow its own momentum and impact onto the airway wall, or
2. follow the changing airstream
inertial impaction depends on - ANSWER 1. particle's momentum - size and flow rate
2. position of particle in the airstream
3. angle of bifurcation
which mechanism is the main mechanism for deposition in upper airways? - ANSWER
Impaction (10 micron size has 50% chance of impaction)
Interception - ANSWER - interception occurs when edge of a particle contacts airway
wall
- major deposition mechanism for elongated particles
Deposition Fraction (DF) - ANSWER mean probability that a particle inhaled is deposited
in the respiratory tract
4 regions of the respiratory tract for deposition - ANSWER 1. extrathoracic region (E) -
airways in head + neck
2. upper bronchial region (UB): trachea + bronchi
3. Lower bronchial region (LB): bronchioles
, 4. Alveolar region (A): alveoli
Important factors which affect deposition - ANSWER 1. particle size - less than 0.5
micron -> exhale, between 0.5 to 5 -> deposit in lower airways, larger than 5 -> deposit in
upper airways or in head and neck
- too small - exhaled out
2. effect of shape - long thin fibres easily deposit in alveoli
3. effect of density - porous particles have lower density
4. effect of humidity - ONCE particles enter the respiratory tract, they are exposed to
high humidity, which affect size, dispersibility, depends on hydrophobic/philic
properties
Hydrophilic particles - ANSWER - once entered airway, absorbed moisture layer, which
increases effective particle size, hence deposit at higher regions of the respiratory tract
Lipophilic particles - ANSWER - not affected as much
Does breathing pattern affect deposition? - ANSWER YES
increasing inhaled volume - ANSWER increase deposition at lower respiratory tract
increased flow rate - ANSWER increase deposition at upper respiratory tract by inertial
deposition
breath holding - ANSWER increase deposition by sedimentation and diffusion
Optimal deposition if - ANSWER 1. slow inspiration (reduces impaction in oropharynx)
2. deep breath (deeper penetration to small airways)
3. breath holding (allow sedimentation / diffusion)
Some examples of locally active inhaled drugs - ANSWER 1. use to treat asthma and
COPD
- beta agonist
- Ach agents
breathing pattern affect deposition? - ANSWER YES
Upper respiratory tract includes - ANSWER nose
pharynx
larynx
Lower respiratory tract - ANSWER trachea, bronchi, bronchioles, alveoli
airway dimensions - ANSWER from trachea to alveolar sacs - airway diameter
decreases from 1.8cm to 0.04cm
Total surface area of alveolar - ANSWER 140 m2 - large surface area allowed for more
gas exchange
physiology of the lung - ANSWER 1. globet cells produces mucus to trap foreign
particles
2. epithelial cells in conducting airways are ciliated - to transport foreign particles
upwards for elimination
What is an aerosol? - ANSWER A suspension of solid or liquid particles in gas
What are the sites of aerosol particle deposition? - ANSWER 1. at back of throat -
swallowed and useless
2. at bronchioles - good for local treatment eg asthma
3. at alveoli - for systemic absorption
4 factors affecting deposition - ANSWER 1. particle properties: size, shape, charge
2. aerosol particles: concentration, velocity of spray, particle size range
3. respiratory tract properties - disease state, geometry
4. breathing patterns - residence time (breath holding), volumetric flow rate (breathing
rate)
Are all particles the same size in an aerosol? - ANSWER - no, they are polydisperse
- a log-normal distribution
aerodynamic diameters (AED) - ANSWER - particles with same AED can be of different
dimensions and shapes
,3 ways in which particles deposit in airways - ANSWER 1. diffusion
2. sedimentation
3. inertial impaction
diffusion of aerosol - ANSWER - very fine particles (less than 0.5 micron) are deposited
by diffusion
- random movement of particles through the gas (Brownian motion)
- rate is inversely proportion to particle size
sedimentation of aerosol particles - ANSWER - sedimentation due to vertical
gravitational force
- Stoke's law applies: sedimentation rate depends on particle size and density
What is the dominant mechanism for deposition for particles between 0.5 to 5 microns -
ANSWER sedimentation
Inertial impaction - ANSWER - particles carried by a gas stream has its own momentum
- particles can either
1. follow its own momentum and impact onto the airway wall, or
2. follow the changing airstream
inertial impaction depends on - ANSWER 1. particle's momentum - size and flow rate
2. position of particle in the airstream
3. angle of bifurcation
which mechanism is the main mechanism for deposition in upper airways? - ANSWER
Impaction (10 micron size has 50% chance of impaction)
Interception - ANSWER - interception occurs when edge of a particle contacts airway
wall
- major deposition mechanism for elongated particles
Deposition Fraction (DF) - ANSWER mean probability that a particle inhaled is deposited
in the respiratory tract
4 regions of the respiratory tract for deposition - ANSWER 1. extrathoracic region (E) -
airways in head + neck
2. upper bronchial region (UB): trachea + bronchi
3. Lower bronchial region (LB): bronchioles
, 4. Alveolar region (A): alveoli
Important factors which affect deposition - ANSWER 1. particle size - less than 0.5
micron -> exhale, between 0.5 to 5 -> deposit in lower airways, larger than 5 -> deposit in
upper airways or in head and neck
- too small - exhaled out
2. effect of shape - long thin fibres easily deposit in alveoli
3. effect of density - porous particles have lower density
4. effect of humidity - ONCE particles enter the respiratory tract, they are exposed to
high humidity, which affect size, dispersibility, depends on hydrophobic/philic
properties
Hydrophilic particles - ANSWER - once entered airway, absorbed moisture layer, which
increases effective particle size, hence deposit at higher regions of the respiratory tract
Lipophilic particles - ANSWER - not affected as much
Does breathing pattern affect deposition? - ANSWER YES
increasing inhaled volume - ANSWER increase deposition at lower respiratory tract
increased flow rate - ANSWER increase deposition at upper respiratory tract by inertial
deposition
breath holding - ANSWER increase deposition by sedimentation and diffusion
Optimal deposition if - ANSWER 1. slow inspiration (reduces impaction in oropharynx)
2. deep breath (deeper penetration to small airways)
3. breath holding (allow sedimentation / diffusion)
Some examples of locally active inhaled drugs - ANSWER 1. use to treat asthma and
COPD
- beta agonist
- Ach agents
