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The flashcards below were created by user
Rx2013
on FreezingBlue Flashcards.
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Drugs absorbed into pulmonary circulation
- avoid first pass
- could be metabolized by enzymes in the respiratory tract
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Aerosols are defined as
colloidal systems of very finely subdivided liquid or solid particles dispered in and surrounded by gas
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3 classes of aerosol products
- space sprays
- surface coating
- aerated sprays
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Disperse active ingredients as a finely divided spray with the particle no longer than 50 micrometer in diameter
space spray
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disperse larger particles generally produce a wet or course spray
- surface coating
- deposited in upper airway
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dispered medication foams, vaginal foams and shaving cream
aerated sprays
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Advantages of aerosol dosage form
- minimum contamination
- maximum stability
- reduces irritation (cooling effect)
- easy to control form, particle size and dose
- clean process
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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
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Aerodynamic diameter
diameter x sq. root of density
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Aerodynamic diameter >2 micrometer
- deposits in oropharynx
- does not reach peripheral lung
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Ideal size for a therapeutic aerosol to penetrate into the tracheo-bronchial tree and smaller airways
5 micrometer
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major constituents of an aerosol
- active ingredient
- antioxidants
- surface active agent
- solvent
- propellant
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fluorinated hydrocarbon
- propellant
- liquified gas mixture
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non-liquified gas
- carbon dioxide
- nitrogen
- nitrous oxide
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Advantages of nitrogen as propellant
- insolube in the product concentrate
- oderless and tasteless gas
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Only propellant suitable for pharmaceutical use
HFCs
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Pressure of an aerosol
- critical to performance
- controlled by type, amount and nature of propellant
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Space spray % propellant
85%
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surface spray % propellant
30-70%
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Aerated spray % propellant
6-10%
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Three types of devices that are commonly used
- metered dose inhaler
- nebulizer
- dry powder inhaler
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AIR particles
- low density
- porous structure
- 5-30 mcm diameter
- aerodynamic diameter of 1-5 mcm
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sustained release
lipid coating the particles
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rapid release
sugar or water soluble particles
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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
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