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

107911

Card Set

ADT Exam 1

Description

Pulmonary Drug Delivery

Updated

2011-10-11T01:19:35Z

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