Understanding Medicinal Drug Delivery Using Dry Powder Inhalers (DPIS)

For a long time, dry powder inhalers (DPI) have been used for treating asthma, and other respiratory diseases, by delivering medication directly to the lungs.

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Dr Gajendra Singh, Assistant Professor, Indian Institute of Technology Mandi, India

Dry powder inhalers (DPI) remain a vital part of our healthcare system due to their extensive use caused by a large number of respiratory patients globally. However, despite their wide use, their inherent inefficiency leads to drug wastage, poor therapy, and high costs to the end-user.

These devices have also been used for the delivery of antibiotics with dry powders also having the ability to be used for nasal inspiration for the treatment of local as well as systemic disorders.

Precise particle size control

When a person inhales orally through a DPI, the air starts moving at high speed within the device. The air lifts the powder sitting inside the DPI or helps to move a capsule that contains the powder. This highspeed airflow eventually helps to aerosolise the drug within the DPI chamber. The chamber, designed to intensify the turbulence of the inhaled air, facilitates the collision of particle clusters with the chamber walls, helping them to “de-agglomerate” into fine particles of the size of a few microns (this is what we want to get to the lungs). Following this complex process, the fine aerosol exits the device and travels to the lungs through the patient’s mouth and airway.