The document discusses therapeutic aerosols, including their definition as disperse systems using gas as a continuous phase, and applications delivering medication directly to affected areas like skin or lungs. Key points covered include formulation aspects, common propellants used, and factors influencing deposition and clearance in the respiratory tract. The uses of aerosols for both local and systemic drug delivery are also summarized.

1. Therapeutic Aerosols
Dr. Basavaraj K. NanjwadeM. Pharm., Ph. D
Department of Pharmaceutics
Faculty of Pharmacy
Omer Al-Mukhtar University
Tobruk, Libya.
E-mail: nanjwadebk@gmail.com
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.

2. CONTENTS
1. Definition and uses, model of operation.
2. Deposition in human respiratory tract.
3. Formulation aspects,
4. Propellants.
5. Packages and containers.
6. Absorption and clearance.
7. Applications.
8. References.
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.

3. Definition and uses
• Aerosols may be defined as disperse phase system, in
which very fine solid particles or liquid droplets get
dispersed in the gas which acts as continuous phase.
Uses:
1. The medicament can be delivered directly to the
affect area such as burnt skin and wound.
2. So it minimises the discomfort caused by mechanical
or manual application
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4. Model of operation
• Drugs are generally delivered to the respiratory tract
for the treatment or prophylaxis of airways diseases,
such as bronchial asthma and cystic fibrosis.
• The administration of a drug at its site of action can
result in a rapid onset of activity.
• Additionally, smaller doses can be administered
locally compared to delivery by the oral or parenteral
routes.
• The pulmonary route is also useful where a drug is
poorly absorbed orally.
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Tobruk, Libya.
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5. Deposition in human
respiratory tract
• Casts of the upper airways have been constructed in
an attempt to predict aerosol deposition in the lungs.
• Most lung deposition models are based on the
influence of particle size on aerosol deposition.
• Breathing parameters, such as breathing frequency
and tidal volume, play a key role in lung deposition.
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Tobruk, Libya.

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Tobruk, Libya.
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Site of Deposition in human
respiratory tract

7. Formulation aspects
• The formulation of pharmaceuticals as therapeutic
aerosols is continually increasing.
• Thus antiseptic materials can be sprayed onto abraded
skin with a minimum of discomfort to the patient.
• One product, ethyl chloride, cools sufficiently on
expansion so that when sprayed on the skin, it freezes
the tissue and produces a local anesthesia.
• This procedure is sometimes used in minor surgical
operations.
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.

8. Propellants
• Propellants develops a pressure in the container.
• Compressed gases such as carbon dioxide or nitrogen
and liquified gases like methane or ethane can be
used as propellants.
• These days propellants like trichloro-fluoro-methane,
dichloro-difluoro-methane, dichloro-tetrafluoro-
ethane and difluoro-ethane are used in
pharmaceutical aerosols.
• The medicaments to be propelled may be solid or
liquid.
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Tobruk, Libya.
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9. Packages
1. They are used for spray bandages and for
application of drugs meant for topical use.
2. They are used for spray administration of drugs into
various body cavities.
3. They are used for administration of drugs such as
local anesthetics, local antiseptic, local analgesics
and anti-inflammatory drugs.
4. They are used to spray cosmetics preparations such
as perfumes.
5. They are used to spray disinfectants, deodorizers
and air sanitizers.
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.

10. Containers
• The containers are made from metal, glass and plastic.
• Pharmaceutical aerosols may be packaged in tinplated
steel, plastic-coated glass or aluminium containers.
• MDIs (Metered-Dose Inhalers) are generally presented
in aluminium canisters, produced by extrusion to give
seamless containers with a capacity of 10-30 mL.
• Aluminium containers with an internal coating of a
chemically resistant organic material, such as an epoxy
resin, can be used.
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.
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Tobruk, Libya.
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Container

12. Absorption
• Hydrophilic materials are poorly absorbed through
membrane pores at rates inversely proporational to
molecular size.
• Some drugs, such as sodium cromoglycate, are partly
absorbed by a saturable active transport mechanism.
• The rate of drug absorption, and consequently drug
action, can be influenced by the formulation.
• Prolonged absorption may be achieved using
suspension formulations or novel drug delivery
systems such as liposomes and microspheres.
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13. Clearance
• Particles deposited in the ciliated conducting airways
are cleared within 24 hours and ultimately swallowed.
• Insoluble particles penetrating to the alveolar regions,
and which are not solubilized in situ, are removed
more slowly.
• Alveolar macrophages engulf such particles and may
then migrate to the bottom of the mucociliary
escalator, or alternatively particles may be removed
via the lymphatics.
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.
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14. Applications
1. The use of aerosols as a dosage form is particularly
important in the administration of drugs via the
respiratory system.
2. In addition to local effects, systemic effects may be
obtained if the drug is absorbed into the bloodstream
from the lungs.
3. Topical preparations are also well suited for
presentation as aerosols.
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Tobruk, Libya.
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15. THANK YOUe-mail: nanjwadebk@gmail.com
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Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya.