Key Points

• Micronized is a term used in the pharmaceutical industry to describe the size of a drug particle. In general, micronized particles are usually less usually than 50 microns, but in the pharmaceutical industry they are generally less than 10 microns.
• A micron is a metric unit of measure and an abbreviated term for “micrometer”, or a millionth of a meter (1 / 1,000,000 meters or 10^-6). A micronized drug particle is about 4 to 10 times smaller than a conventional drug particle. The symbol for micron is “µm”.
• Reducing the particle size of a drug helps it to dissolve and absorb more easily into your body so it can reach its site of action (improved bioavailability).

Why are drugs micronized?

Many drugs are poorly water soluble, which means they do not dissolve well. Poorly dissolved drugs have low oral bioavailability in the body. Drug particles can dissolve more quickly if they are reduced to a very small size, or “micronized”.

Micronized particles have a greater surface area, allowing better interaction with solvents like body fluids. This improves the solubility of the particles and enhances absorption. Certain drugs need to be micronized so they have better solubility and can reach the area of drug activity.

Trying to imagine something less than 10 microns is difficult. Common items and their corresponding micron size include:

• viruses: 0.005-0.3 microns
• red blood cell: 5-10 microns
• human sneeze: 10-100 microns
• human hair: 70 microns
• coarse sand: 500 microns
• cayenne pepper: 15-1000 microns
• eye of a needle: 1230 microns
• measure of one inch: 25,400 microns
• coarse gravel: 15,000 - 30,000 microns

What are the benefits of micronization?

• Reducing particle size through micronization can have a positive impact on the shelf life and stability of medications.
• Micronization is an efficient and cost-effective process and can produce larger volumes of drugs.
• Micronization is well-recognized as a standard and proven process by pharmaceutical regulatory agencies like the FDA.
• Creams or ointments are more aesthetically pleasing when particles are not visible or gritty.

Nanotechnology can produce even smaller drug particles than micronization, but it is more costly. “Nano" means one-billionth of a meter or 10^-9; therefore one nanometer is one-billionth of a meter.

What drugs are micronized?

Particle size can be important for drugs that are absorbed by many different routes, including oral, topical (such as a cream or ointment), transdermal (via a skin patch), inhalation (for example, dry powder inhalers for asthma or other lung disease), or by injection.

Examples of drugs that contain micronized particles include:

• Glynase PresTab (glyburide)
• Yonsa (abiraterone)
• Antara (fenofibrate)
• Prometrium
• Colestid (colestipol hydrochloride)
• Trelegy Ellipta (fluticasone furoate, umeclidinium bromide and vilanterol trifenatate)

Compounding pharmacies may also use micronized drug particles when preparing medicine formulations, such as topical creams, vaginal creams, suppositories or ointments.

Many pharmaceutical products may contain micronized particles. To determine if a medicine has micronized particles, ask your pharmacist, or you can look under the “Description” section in the manufacturer package insert.

How are micronized particles made?

In the pharmaceutical industry, a common method of making micronized particles is by using the “jet mill” technology. This process allows high velocity collisions of particles through the milling process.

• As the mill turns, centrifugal force allows heavier particles to fall while the smaller ones are suspended in a nitrogen gas or compressed air.
• Smaller particles can be collected while larger particles remain in the mill for further processing.
• During the milling process, particle size can be manufactured to specification.

References

• Catalent. Micron Technologies. Accessed Sep 16, 2022 at https://www.catalent.com/oral-dose/dose-form-design/tablets-capsules/catalent-micron-technologies/particle-size-reduction-services/
• Tran M. Harbor Compounding Pharmacy. Size Does Matter: The Importance of Micronized Drugs. Accessed Sep 16, 2022 at https://www.harborcompounding.com/size-does-matter-the-importance-of-micronized-drugs
• Particle size. The Engineering Toolbox. Accessed Sep 16, 2022 at https://www.engineeringtoolbox.com/particle-sizes-d_934.html
• Pharmaceutical Size Reduction: How Size Affects Stability, Appearance & Properties. BEE International. Accessed Sep 16, 2022 at https://www.beei.com/blog/pharmaceutical-size-reduction-how-size-affects-stability-appearance-properties

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