Aerosols. Aerosols:. Definition: products that depend on the power of a compressed or liquefied gas to expel the contents from the container. Aerosols are termed also pressurized package .
Components of aerosols:
For oral and inhalation:
eg. Fluorinated hydrocarbons Dichlorodifluromethane (propellent 12) Dichlorotetrafluromethane (propellent 114)
For Topical preparation:
A- Liquefied gas
and atmospheric pressure exist in the gaseous or
vapor state and are capable of being liquefied at
relatively low pressures or temperatures.
B- Compressed Gas Propellants
occupy the head space above the liquid
in the can.
Tinplated steel :
** Metal containers may be further coated with organic coating, e.g. oleoresin, phenolic, vinyl or epoxy coating for additional protection.
Plastic coated glass:
In most aerosol cans, the bottom curves inward. This serves two functions:
1-The shape strengthens the structure of the can. If the can had a flat bottom, the force of the pressurized gas might push the metal outward. A curved bottom has greater structural integrity.
2-The shape makes it easier to use up all the product.
1- Continuous spray valve
2- Metering valves
- contains ingredients or mixture of active ingredients and other such as solvents, antioxidants and surfactants
blend of various propellants
Agglomeration, caking, particle-size growth and valve clogging (closing).
1-lubricants: isopropyl myristate, oleic acid
2- Surfactants: to disperse particles
3- Dispersing agents: oleic acid, lecithin
4- The particle size of metered-dose inhalant should be between 2 – 8 um, while those for topical aerosols should be 50 – 100 um.
This test indicates the effect of an aerosol formulation on the extension of an open flame.
- Product is sprayed for 4 sec. into flame.
2- Flash point
Determined by using standard Tag Open Cap Apparatus.
1- Vapor pressure
Determined by pressure gauge
Variation in pressure indicates the presence of air in headspace.
Determined by hydrometer or a pychnometer.
By Karl Fischer method
4- Identification of propellants
1- Aerosol valve discharge rate
2- Dose uniformity
- To determine amount of medication actually received by the patient.
3- Net contents
Used to estimate the weight loss over a 1-year period.
5- Particle size distribution