aerosols Flashcards
(53 cards)
what is a dispersed system
undissolved or immiscible particles
(drug) distributed throughout a vehicle.
what is the dispersed phase
The substance that is distributed
what is the dispersing phase\ dispersion medium
the vehicle
what are aerosols
are pressurized dosage forms that upon actuation emit a fine
dispersion of liquid and/or solid materials containing one or more active ingredients in a gaseous medium.
how is the pressure applied in aerosols
through the use of one or more liquefied or gaseous
propellants.
what are the physical statues of the propellant
liquefied gas or a
compressed gas.
what is the physical form of the contents that are emitted through aerosols
a fine mist; a coarse, wet, or dry spray; a steady stream; or
a foam
on what does the physical form depends on
► The physical form selected is based on the intended use.
► An aerosol used for inhalation therapy, as in the treatment
of asthma or emphysema, must present particles in the
form of a fine liquid mist or as finely divided solid particles.
is the particle size important for dermatologic sprays
it is coarser and generally less critical
to the therapeutic efficacy of the product.
Some dermatologic aerosols present the medication in the
form of a powder, a wet spray, a stream of liquid ,or an
ointment-like product.
give examples on everyday use items that are aerosols
personal deodorant sprays, perfumes and
colognes, sprays, paint sprays, lubricants and a
number of pet products
what are the advantages of aerosols
- A portion of medication may be easily withdrawn from the
package without contamination or exposure to the remaining
material. - By virtue of its hermetic character, the container protects
medicinal agents adversely affected by atmospheric oxygen, light and moisture. it also keeps them steril.
3-Topical medication may be applied in a uniform
thin layer to the skin without anything else. which reduces irritation and also provide a cooling and refreshing effect.
4-the physical form and the particle size of the emitted
product may be controlled, which may contribute to the
efficacy of a drug, as with the fine controlled mist of an
inhalant aerosol.
- Aerosol application is a clean process, requiring
little or no wash up by the user
what are the two main parts of aerosols
product concentrate and propellant
what is the product concentrate
the active ingredient of the aerosol
combined with the required adjuncts, such as antioxidants,
surface active agents, and solvents, to prepare a stable and
efficacious product.
what is the role of liquefied propellants
it frequently serves the dual role of propellant and
solvent or vehicle for the product concentrate.
what was the most common propellant and why did we stop using them
A chlorofluorocarbon (CFC) is an organic compound , They reduce the amount of ozone in the stratosphere,
when can we use CFCs
(a) there are no technically feasible alternatives
to the use of a CFC propellant in the product.
b) the product provides a substantial health or
other public benefit unobtainable without the
use of the CFC.
(c) the use does not involve a significant release of CFCs
into the atmosphere or, if it does, the release is warranted
by the benefit conveyed.
give examples on CFCs
dichlorodifluoromethane dichlorotetrafluoroethane,
trichloromonofluoromethane
how can we liquefy a gas
by cooling and pressure For example, dichlorodifluoromethane will form a liquid when cooled to −30°C or when compressed to 70 psig (pounds per square inch gauge) at 21°C .
what is the advantage for using liquid propellants
Therefore the system has a constant vapor pressure as
long as it still contains a liquid phase.
what are the types of gases used in the compressed gas propellants
- insoluble gases in liquid phase of aerosol;
► e.g., Nitrogen…. will result in emission of a product in
essentially the same form as it was placed in the container.
►Nitrogen is odorless, tasteless and inert towards the other
components of aerosol and protects the product from
oxidation. - Slightly soluble gases in liquid phase of aerosol…… These may be employed when their expulsion with the product concentrate is
desired to achieve spraying or foaming
► E.g., Carbon dioxide and nitrous oxide.
what is the biggest difference between compressed gas and liquid gas aerosols
Unlike aerosols prepared with liquefied gas
propellant, compressed gas filled aerosols have no
reservoir of propellant. Thus higher gas pressures
are required in these systems, where the pressure
in these aerosols diminishes as the product is
used.
how can we control the pressure of an aerosol
(a) the type and amount of propellant and
(b) the nature and amount of product
concentrate.
what is space sprays aerosols
► Space sprays generally contain a greater proportion of
propellant than do surface aerosols.
► Space aerosols usually operate at 30 to 40 psig at 21°C
and may contain as much as 85% propellant.
what are surface aerosols and foam aerosols
Surface aerosols commonly contain 30% to 70% propellant
with pressures between 25 and 55 psig at 21°C.
• Foam aerosols usually operate between 35 and 55 psig at
21°C and may contain only 6% to 10% propellant,Foam aerosols may be considered to be emulsions, because the liquefied propellant is partially emulsified with the product concentrate rather than being dissolved in it.
