The application of aerosol in the pharmaceutical industry

Aerosols consist of drugs, additives, propellants, pressure-resistant containers and valve systems.

Aerosol means that the medicine, emulsion or suspension is encapsulated in a pressure-resistant container with a special valve system together with a suitable propellant. Preparations that are inhaled in the lungs or sprayed directly to the mucous membranes, skin and spaces of the cavity for disinfection.

Aerosols can act locally or systemically in the respiratory tract, skin or other cavities. At present, aerosols have been used in medical treatment to treat asthma, scalds, ear, nose and throat diseases, as well as expectorant, vasodilation, cardiotonic, diuretic, etc., and have received significant effects.

Aerosol classification: by dispersion system – solution type (hair spray) – suspension type – emulsion type (foam aerosol, hair-setting)

Aerosol classification: by medical use – respiratory type – skin, mucous membrane type – space disinfection type (air freshener, etc.)

Aerosol classification: according to the composition of the phase – two-phase aerosol: generally refers to a solution-type aerosol, which is composed of two phases of gas and liquid. The gas phase is the vapor produced by the propellant, and the liquid phase is the homogeneous solution formed by the drug and the propellant. Three-phase aerosols: generally refer to suspension-type aerosols and emulsion-type aerosols, which are composed of gas-liquid-solid or gas-liquid-liquid three phases.

Disadvantages of aerosols Pressure-resistant containers and valve systems, preparation of special mechanical equipment for cooling and filling, high cost, work by the pressure of the propellant, easy to fail if the package is not sealed, and a certain internal pressure to prevent impact and explosion When the propellant is atomized, it absorbs energy and has a cooling effect, which may cause discomfort to the injured skin.

Aerosols should meet the following relevant regulations during production and storage:

1. Aerosols should be prepared in a clean, germ-free environment. The utensils, containers, etc. must be cleaned and sterilized by appropriate methods. Care should be taken to prevent microbial contamination during the preparation.

2. When preparing an aerosol, an appropriate amount of additives such as antioxidants or bacteriostatic agents can be added according to the properties of the drug. Inhalation aerosols, aerosols for skin and mucous membranes should have no adverse irritation.

3. The fineness of the mist or drug particles for inhaling aerosols should be controlled under 10 μm, and most of the particles should be less than 5 μm.

4. Commonly used propellants for aerosols are trichlorofluoromethane (F11), dichlorodifluoromethane (F12) and dichlorotetrafluoroethane (F114), etc. and other compressed gases such as carbon dioxide, nitrogen, etc. According to the required pressure of the aerosol, two or more propellants can be mixed and used in suitable proportions.

5. The container of the aerosol should not have physical and chemical interactions with the contents, and should be able to withstand the pressure required for the aerosol. Glass bottles or metal containers can be used, and the outer wall of the glass bottle should be lined with a plastic protective layer of appropriate thickness. If a metal container is coated with a protective layer, it must be ensured that the coating cannot soften, dissolve or fall off.

6. The springs, valve stems, dosing cups and rubber gaskets and other components in the aerosol valve adjustment system should not have physical and chemical interactions with the liquid, and their dimensional accuracy and swelling must meet the requirements. The quantitative valve used for inhaling aerosols should be able to release uniform mist particles per injection, and the amount released should be accurate, and the valves used for topical aerosols should be able to continuously spray mist particles.

7. Aerosols must be checked for leaks and explosions by using appropriate methods to ensure safe use.

8. Aerosols should be stored in a cool and dark place, and avoid exposure to sunlight, heat, beating and impact.

9. Aerosols with a quantitative valve should indicate the filling volume of each bottle, the content of the main drug, the single spray dose or the total weight of the content in a single spray.

Spray test:

1. Non-quantitative valve aerosol: Take 4 bottles of the test sample, press the valve for a few seconds to spray, wipe clean, accurately weigh, put it in a 25+1 ℃ water bath for half an hour, take it out, wipe it dry, and press the valve to spray accurately for 5 minutes. , wipe clean, weigh them precisely, and then put them in a 25+1°C water bath, repeat the operation 3 times according to the above method, and calculate the average spray rate of each bottle in g/s, which should comply with the regulations under this category.

2. Quantitative valve aerosol: Take 4 bottles of the test sample, spray several times, wipe clean, accurately weigh, spray once, wipe clean, and then accurately weigh, the difference between the two weights before and after is the amount of one spray , after measuring the spray volume for 3 times according to the above method, spray continuously for 10 times regardless of the weight; then measure the spray volume continuously for 3 times according to the above method, and then spray continuously for 10 times regardless of the weight, and finally measure the spray volume for 4 times according to the above method quantity. Calculate the average value of 10 sprays before and after each bottle and compare it with the marked spray, and the difference limit should be within +20% of the marked spray.