Aerosol particle size analysis in inhalers

Aerosols, including metered dose inhalers and dry powder inhalers, have the ability to deliver drugs to the lungs, which makes these devices important in medicine and pharmacy. A critical component in these aerosols includes the particle size distribution and shape. The importance of particle size analysis in aerosols will be explored later in this article for the application of inhalers.

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context

Aerosols are made up of solid or liquid particles that can be suspended in a gas called a propellant; pharmaceutical aerosols comprise fine particles of a drug that is contained under tight pressure in a container. These particles are then released as a spray when applied by a patient at the push of a button.

Pharmaceutical aerosols can be inhaled through the mouth and can be delivered into the airways for the treatment of various disorders, including associated lung diseases. These aerosols can be stored in two types of inhalers, such as metered dose inhalers (MDI) as well as dry powder inhalers (DPI).

Metered-dose inhalers can be used to provide patients with a particular dose of various medications and can be used to relax muscles in the airways as well as help reduce inflammation. DPIs can be used as alternatives to conventional aerosol-based inhalers and can produce a powder that carries a treatment dose to the lungs in powder form.

These treatments can be used for the treatment of lung diseases associated with airway obstruction leading to breathing difficulties, as well as other disorders such as asthma and respiratory infections.

Test methods

The particles in an aerosol require characterization in order to develop pharmaceutical formulations of drug treatment. The biodistribution and absorption of the drug can determine the effectiveness of the treatment, which means the importance of analyzing the particle size.

Microscopy can be used to characterize particle size to develop aerosol inhalers; this method is uniquely capable of visualizing and measuring individual particles and providing quantitative and qualitative data on particle characteristics such as size and shape.

Automated instrumentation techniques can also be used to size large volumes of particles in a short period of time; however, these are not as good at providing full observational detail regarding particles.

Laser diffraction, an automated instrumentation technique, is able to provide information on particle size distribution and can be useful in developing inhaler aerosols. This type of particle analysis instrument involves the use of a laser which can be used on a sample and which is diffracted by particles of different sizes which produce a light pattern of diffraction. This measurement tool is capable of measuring particle sizes between 0.02 and 2000 micrometers and can collect data on how particle size distribution can affect products and processes, which can also have an effect on other factors such as reactivity and dissolution rate.

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While this method can be useful, it can only reflect particle size at a primary level, which may not accurately reflect what happens when particles are deposited when used by patients in a real setting. . This does not take into account any associated clumping that may occur after the drug particles are ejected from an aerosol inhaler. However, the use of other methods, such as microscopes and impactors capable of testing aerosol inhalation in sample chambers, may be more effective.

Research in this scientific area is important for the development of effective aerosol inhalers, with various researchers using different strategies. An example of this includes scanning electron microscopes, which have been studied to examine the particle size and particle size distribution of drugs delivered by metered-dose inhalers.

In search in the Journal of Medical Sciencesthe researchers used an automated image analysis technique involving the scattering of aerosol particles in an Andersen cascade impactor for a simulation of particle behavior when the drug is inhaled.

This research was able to analyze the particle size distribution using microscopic methods as well as improvement strategies, which can be beneficial for pharmaceutical research in the development of various drugs.

Significance and future prospects

The optimal aerodynamic particle size distribution for aerosol inhalers has been noted to be between 1 and 5 micrometers; this is important because aerodynamic particle size includes factors such as particle density and shape, which are also related to physical particle size and the volume equivalent diameter of a sphere, using a formula. Particle size analysis can aid in the development of inhaler aerosols, which are best suited to transport various drug formulations to achieve efficient absorption into tissues.

The size and distribution of particles in aerosols can reflect the deposition of the drug, and with further research in this scientific field, advances in medicine can be continued to ensure high quality treatment for patients with various diseases and respiratory disorders.

With 65 million people suffering from chronic obstructive pulmonary disease and 3 million deaths from this disease per year, the need for innovative treatments for lung disease is critical. The global impact of respiratory disease has become a burden on health systems and can affect quality of life; Particle size analysis for the development of effective aerosol inhalers can help reduce this burden and improve patient treatment efficiency.

References and further reading

Who.int. 2022. The Global Impact of Respiratory Diseases. [online] https://www.who.int/gard/publications/The_Global_Impact_of_Respiratory_Disease.pdf#:~:text=About%2065%20million%20people%20suffer%20from%20chronic%20obstructive,of%20childhood%20affecting%2014%25%20of %20all%20children%20in the world.

Rawal, S. and Patel, M., 2018. Lipid Nanoparticle Systems. Lipid nanocarriers for drug targeting, pp.49-138. Available at: https://www.sciencedirect.com/science/article/pii/B9780128136874000025?via%3Dihub

Feddah, M. and Davies, N., 2003. Alternative methods for aerosol particle size analysis for metered dose inhalers. Journal of Medical Sciences, 4(1), p.63-69. Available at: https://scialert.net/abstract/?doi=jms.2004.63.69

Abdo, R., Saadi, N., Hijazi, N. and Suleiman, Y., 2020. Quality control and evaluation of pharmaceutical aerosol tests. Drug delivery systems, pp.579-614. Available at: https://www.sciencedirect.com/science/article/pii/B9780128144879000120?via%3Dihub

Mitchell, J. and Nagel, M., 2022. Particle size analysis of medicinal inhaler aerosols. [online] Jstage.jst.go.jp. Available at:https://www.jstage.jst.go.jp/article/kona/22/0/22_2004010/_pdf/-char/en>

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