Aerosols provide advantages over other dosage forms such as easy withdrawal of medication without contamination and protection from atmospheric conditions. Aerosols contain therapeutic ingredients that are dispersed as fine particles upon actuation. They work by using a propellant to develop pressure and expel the product through a valve. Aerosols protect unstable drugs and deliver medication in a uniform, controlled manner. Common aerosol types include metered dose inhalers and dry powder inhalers used to treat respiratory conditions.

1. AEROSOL
Nirmal Raj Marasine (Clinical Pharmacist,
M.Pharma)
WHSA

2. The advantages of Aerosol over other
dosage forms
• A portion of medication may be easily withdrawn from
the container without contamination or exposure to the
remaining materials
• Due to its hermetic character, the aerosol container
protects the product from adverse effects of
atmospheric air and moisture.
• Being opaque, the aerosol container also protects the
drugs from light throughout the shelf life
• Topical aerosols may be applied in a uniform thin layer
to the skin without touching the affected.

3. DEFINITION
• "Aerosol is a pressurized dosage forms containing one
or more therapeutic active ingredients which upon
actuation emit a fine dispersion of liquid and/or solid
materials in a gaseous medium.

4. ADVANTAGES
• Easily withdrawn of drug
• Easy and convenient to apply.
• Faster Onset of action.
• No manual/ direct contact with
the medicament.
• Avoid the first pass
metabolism.
• A specific amount of dose or
drug can be removed.
• No microorganism can enter.
• Release the contents in
Controlled and Uniformly.
• Protect the photosensitive
medicaments and oxygen
sensitive material.
• Provides efficacy of a drug.
• Irritation can be reduced.
DISADVANTAGES
• Costly.
• Difficult disposal of empty
aerosol containers.
• Allergic in some cases.
• Explosive.
• Some formulation is
difficult.
• Sometimes propellants
may cause toxic reactions

5. Working principle of aerosol
• When a liquefied propellant mixture is sealed within an aerosol
container with the drug ingredients, equilibrium is quickly
established between the portion of propellant that remain
liquefied and that which vaporizes and occupies the upper
portion of the aerosol container.
• The vapour phase exerts pressure in all directions inside the
container and it is the pressure that upon actuation of the
aerosol valve forces the liquid phase up the dip tube and out of
the valve into the atmosphere. As the propellant meets the air,it
expands and evaporates because of drop in pressure leaving
the ingredients as liquid droplets or dry particles depending
upon the formulation.

7. Mode of operation
• Liquefied gases have been used widely as propellants for
most aerosol products
• When a liquefied-gas propellant is placed into a sealed
container, it immediately separates into a liquid and a vapor
phase.
• some of the molecules will leave the liquid state and enter
the vapor state. As molecules enter the vapor state, a
pressure gradually develops.
• As the number of molecules in the vapor state increases, the
pressure also will increase. Equilibrium is attained between
the numbers of molecules changing from a liquid to a vapor
and from a vapor to a liquid. The pressure at this point is
referred to as the vapor pressure .

8. • This vapor pressure is exerted equally in all directions and is
independent of the quantity of liquefied gas present
• The pressure exerted against the liquid phase is sufficient to
push the latter up a dip tube and against the valve.
• When the valve is opened, the liquid phase is emitted and
comes into contact with the warm air at atmospheric pressure
and propellant immediately reverts to the vapor state.
• As the contents of the container are expelled, the volume within
the container occupied by the vaporized propellant increases,
causing a temporary fall in pressure
• However, as soon as the pressure decreases, a sufficient
number of molecules change from the liquid state to the vapor
state and restore the original pressure.

9. COMPONENTS OF AEROSOLS
1.Propellant
2.Container
3. Valve and actuator
4. Product concentrate

10. 1.PROPELLANTS
• Responsible for developing proper pressure within the
container.
• Provide driving force to expel the product from the
container.
TYPES OF PROPELLANTS
• Compounds useful as propellants can be classified as the
following:
• Liquefied gases
• Chlorofluorocarbons (CFC)
• Hydrochlorofluorocarbons (HCFC)
• Hydrofluorocarbons (HFC) or Hydrofluoroalkaines (HFA)
• Hydrocarbons (HC)
• Hydrocarbon ethers
• Compressed gases

11. 2.CONTAINERS
• They must be able to withstand pressures as high as
140 to 180 psig (pounds per sq. inch gauge) at 130 ° F.
AEROSOL CONTAINERS
A . Metals
1. Tinplated steel
2. Aluminum
3. Stainless steel
B. Glass
1. Uncoated glass
2. Plastic coated glass

12. 3.VALVES
• Easy to open and close .
• Capable of delivering the content in the desired form
such as spray, foam, solid stream etc.
• It can deliver a given amount of medicament .
TYPES OF VALVES :
• 1.Continuous spray valve
• 2.Metering valves

13. CONTINUOUS SPRAY VALVE
• Used for topical aerosols .
• Valves assembly consists :
• Ferrule or mounting cup
• Valve body or housing
• Stem
• Dip tube
• Gasket
• Spring

14. METERING VALVES
• Used for dispensing of potent medication.
• Operates on the principle of a chamber whose size
determines the amount of medication dispensed.
• Approximately 50 to 150 mg ±10 % of liquid materials
can Abe dispensed at one time with the use of such
valve

15. 4.ACTUATORS
• These are specially designed buttons which helps in
delivering the drug in desired form i.e., spray, wet
stream, foam or solid stream .
• TYPES OF ACTUATORS :
• Spray actuators
• Foam actuators
• Solid steam actuators
• Special actuators

16. • SPRAY ACTUATORS:
• It can be used for topical preparation, such as antiseptics,
local anesthetics and spray on bandages etc.
• It allows the stream of product concentrate and propellant to
pass through various openings and dispense as spray.
FOAM ACTUATORS :
• It consist of large orifice which ranges from 0.070—0.125
inch .
SOLID STREAM ACTUATORS :
• These actuators are required for dispensing semi solid
products such as ointments .
SPECIAL ACTUATORS :
• These are used for a specific purpose.
• It delivers the medicament to the appropriate site of action
such as throat, nose, dental and eyes etc.

17. 5.PRODUCT CONCENTRATE
• Other excipients are perfumes, flavoring, preservatives,
antioxidant buffering agents, surfactants etc.

18. METERED DOSE INHALERS
• Used to minimize the number of administration errors.
• To improve the drug delivery of aerosolized particles into the
nasal passageways and respiratory tract.
Advantages of MDI:
• It delivers specified amount of dose .
• Portable and compact.
• Quick to use , no contamination of product.
• Dose-dose reproducibility is high.
Disadvantages of MDI :
• Low lung deposition ; high pharyngeal deposition .
• Coordination of MDI actuation and patient inhalation is
needed.

20. Dry powder inhaler
• DPI are devices through which a dry powder formulation of an
active drug is delivered for local or systemic effect via the
pulmonary route
• Used to treat respiratory diseases such as asthma, COPD,
bronchitis etc.
• Dry powders for inhalation are formulated either as loose
agglomerates of micronized drug particles with aerodynamic
particle sizes of less than 5 μm
• Where as for systemic effects particle size of less than 2 μm is
needed for drug deposition in the small peripheral airways.

21. why use Inhalers?
• Rapid action Smaller dose is required Portable (Easy
to handle)
• No co-ordination required Suitable for all patient Easy
to administration of drug Avoid 1 st pass metabolism
Good bioavailability
• No dose counter is required

22. Advantages
• Propellants free design.
• Provides rapid drug action.
• High drug dose carrying capacities, reproducibility
(Monodisperse).
• low device retention and low exhaled loss.
• Provides local action within the respiratory tract and
are non-invasive.
• Better patient compliance, simple to use and
convenient to carry and do not require spacers.
• Less potential for formulation problems.

23. Disadvantages
• Deposition efficiency depends on patients inspiratory
airflow.
• Greater potential problems in dose uniformity.
• Less protection from environmental effects, Humidity
may cause powders to aggregate and capsules to
soften.
• Dose lost if patient inadvertently exhales into the DPI
• More expensive than pressurized metered dose
inhalers