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ADT Exam 1
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Drugs absorbed into pulmonary circulation
avoid first pass
could be metabolized by enzymes in the respiratory tract
Aerosols are defined as
colloidal systems of very finely subdivided liquid or solid particles dispered in and surrounded by gas
3 classes of aerosol products
space sprays
surface coating
aerated sprays
Disperse active ingredients as a finely divided spray with the particle no longer than 50 micrometer in diameter
space spray
disperse larger particles generally produce a wet or course spray
surface coating
deposited in upper airway
dispered medication foams, vaginal foams and shaving cream
aerated sprays
Advantages of aerosol dosage form
minimum contamination
maximum stability
reduces irritation (cooling effect)
easy to control form, particle size and dose
clean process
Advantages of therapeutic aerosols
drug acts very rapidly
local high concentrations for higher activity
reduced systemic side effects
lower doses needed than if taken PO or IV
Aerodynamic diameter
diameter x sq. root of density
Aerodynamic diameter >2 micrometer
deposits in oropharynx
does not reach peripheral lung
Ideal size for a therapeutic aerosol to penetrate into the tracheo-bronchial tree and smaller airways
5 micrometer
major constituents of an aerosol
active ingredient
antioxidants
surface active agent
solvent
propellant
fluorinated hydrocarbon
propellant
liquified gas mixture
non-liquified gas
carbon dioxide
nitrogen
nitrous oxide
Advantages of nitrogen as propellant
insolube in the product concentrate
oderless and tasteless gas
Only propellant suitable for pharmaceutical use
HFCs
Pressure of an aerosol
critical to performance
controlled by type, amount and nature of propellant
Space spray % propellant
85%
surface spray % propellant
30-70%
Aerated spray % propellant
6-10%
Three types of devices that are commonly used
metered dose inhaler
nebulizer
dry powder inhaler
AIR particles
low density
porous structure
5-30 mcm diameter
aerodynamic diameter of 1-5 mcm
sustained release
lipid coating the particles
rapid release
sugar or water soluble particles
Advantages of AIR
large size and small aerodynamic size
require less power for dispersion
up to 50mg of powder can be administered with each inhalation
low cohesion between particles
high % of particles deposited in deep lung tissue
breath activated inhaler
Author
Rx2013
ID
107911
Card Set
ADT Exam 1
Description
Pulmonary Drug Delivery
Updated
10/11/2011, 1:19:35 AM
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