Lecture 8 Pharmaceutical Aerosols

Question 1

What is a pharmaceutical aerosol?

Answer 1

Pressurized dosage forms containing one or more active ingredients which upon actuation emit a fine dispersion of liquid and/or solid materials in gaseous medium. Similar to other dosage forms but depend a lot on their container.
Depend on the function of the container, the valve assembly and propellant for proper delivery of the medication.

Question 2

What are the advantages of Pharmaceutical Aerosols?

Answer 2

Convenience of use, improved stability, delivered of the medication to the affected area in the desired form, irritation produced by the mechanical application of topical medication is reduced or eliminated, application of medication in a thin layer, delivery to the respiratory system, expensive drugs can be economically applied by suitable metering valves.

Question 3

What are the disadvantages of pharmaceutical aerosols?

Answer 3

Cost of manufacturing and packaging, potential toxicity or adverse reactions from propellant, limitation of present aerosol technology (only about 10-20% of drug can reach the target region of the respiratory system. User complaints of clogging, loss of spraying power, and product left in can)

Question 4

How can the pressure of an aerosol be controlled?

Answer 4

By the type and amount of propellant.

The nature and amount of material comprising the product concentrate.

Question 5

What are the components of an aerosol product?

Answer 5

Product Concentrate
Propellant
Container
Valve and Actuator

Question 6

What is the product concentrate?

Answer 6

The active ingredient of the aerosol combined with the required excipients, such as antioxidants, surface active agents, and solvents. (preservatives are not always necessary)

Question 7

What dosage form can a product concentrate be?

Answer 7

Suspension, emulsion, solution, semisolid, or powder.

Question 8

What are the properties of an ideal propellant?

Answer 8

Able to supply the necessary force to expel product.
Chemically inert
Colorless
Odorless
Good solvent properties
Non-toxic
Practical Cost
Environmentally safe
Non-flammable

Question 9

What are two types of propellants?

Answer 9

Liquefied Gas

Compressed Gas

Question 10

What is the temperature and pressure that a liquefied gas should have as a propellant?

Answer 10

A vapor pressure greater than atmospheric pressure at a temperature of 105 degrees Fahrenheit

Question 11

What are examples of a soluble compressed gas propellant?

Answer 11

nitrous oxide, carbon dioxide

Question 12

What are examples of insoluble compressed gas propellant?

Answer 12

Nitrogen

Question 13

What propellant is being phased out due to reduction of ozone in the stratosphere?

Answer 13

Chlorofluorocarbons (CFCs)

Question 14

What is replacing CFCs as a safe, effective, and environmentally-friendly alternative?

Answer 14

Hydrofluoroalkanes (HFAs)

Question 15

What type of containers can be used for aerosols?

Answer 15

Uncoated or plastic coated glass
Metal, including tin-plated steel, aluminum
Plastics

Question 16

What is the function of a valve assembly?

Answer 16

To permit the expulsion of the contents of the can in the desired form, at the desired rate, and in the proper amount or dose.

Question 17

What materials can be used for a valve assembly?

Answer 17

Plastic, Rubber, aluminum, and stainless steel

Question 18

What are the modes of operation for a liquefied gas system?

Answer 18

Two phase system

Three phase system

Question 19

What are the modes of operation for a compressed gas aerosol?

Answer 19

Solid stream dispensing

Foam Dispensing

Question 20

What is a liquefied gas system?

Answer 20

Part of the propellant is present as liquid and part as vapor in equilibrium with liquid.
Produces more constant power than compressed gas system.

Question 21

What is a two phase system?

Answer 21

Solution or suspension of active ingredient in a liquid propellant or a mixture of a liquid propellant and solvent.
As drug leave the orifice, rapid expansion of propellant, and this produces a fine spray.

Question 22

What is a three phase system?

Answer 22

Comprised of a layer of water-immiscible liquid propellant, a layer of highly aqueous product concentrate, and the vapor phase. Upon activation of the valve, the pressure of the vapor phase causes the liquid phase to rise in the dip tube and be expelled from the container.

Question 23

What is a compressed gas system?

Answer 23

Gas is compressed in the container and expansion the compressed gas provides the push or the force necessary to expel the contents.

Question 24

If a gases that is insoluble in the product concentrate is used as parte of a compressed gas system what is the result?

Answer 24

The emission of a product that is essentially the same form as it was when placed in the container.

Question 25

If no reservoir of propellant is used in a compressed gas system what is required?

Answer 25

Higher gas pressures are required and the pressure progressively diminishes as the product is used.

Question 26

What dosage from is the concentrate(dispensed product) of a solid stream dispensing compressed gas aerosol?

Answer 26

Semisolid

Question 27

What is the pressure used for solid stream dispensing compressed gas aerosols?

Answer 27

very high pressure of 90-100 psig at 70 degrees Fahrenheit, 21 degrees Celsius.

Question 28

What is an example of a solid stream dispensing compressed gas aerosol?

Answer 28

Dental creams, hair dressings, food products

Question 29

How does a foam dispensing compressed gas aerosol work?

Answer 29

The gas is dissolved in the concentrate which expands on exiting from the aerosol to form foam.

Question 30

What are the gases used in foam dispensing compressed gas aerosols?

Answer 30

Nitrous oxide and carbon dioxide.

Question 31

What is a system that utilizes a metered-valve system to regulate the amount of drug discharged upon actuation?

Answer 31

Metered dose inhalers

Question 32

What are the different types of filling operations?

Answer 32

Cold Filling and Pressure Filling

Question 33

What is cold filling?

Answer 33

Product concentrate and propellant must be cooled to temperatures of -30 to -40 degrees F.
Chilled product concentrate is measured into a cold aerosol container, followed by the addition of the liquefied gas.
Valve is inserted and crimped into place.
Aqueous systems cannot be filled by this process.

Question 34

What is pressure filling?

Answer 34

Product concentrate is quantitatively placed in the aerosol container.
Valve assembly is inserted and crimped into place.
Pressurized liquefied gas is metered into the valve stem from a pressure burette.
Used for most pharmaceutical aerosols.

Question 35

What are important parts of packaging, labeling, and storage?

Answer 35

Package is part of manufacturing process
Protective cap or cover to prevent accidental use.
Storage in reasonable temperature.
Protect from excess heat and flame
Dispose of properly