This bisected model of a child’s airway allows the researchers to test new inhaler designs to reduce drug deposition in the mouth and throat, increase penetration of particles into the lungs, and allow weak inhalation from a young child or very sick person to pull enough medicine into the lungs. Credit: Southwest Research Institute
Researchers are developing new inhaler designs aimed at delivering medicine more reliably to young children and others who can't manage the strong, deep breath that standard inhalers require.
For the project, based at the Southwest Research Institute, a multidisciplinary team combined computational fluid dynamics, particle science and pharmaceutical science to redesign how inhalers deliver drugs.
"For children and people with conditions like chronic obstructive pulmonary disease, or COPD, some inhalers don't reliably get enough medicine into the lungs," said Raouf Tajik, research engineer in SwRI's Mechanical Engineering Division and the project's leader. "A lot of the medication remains in the mouth and throat or within the device instead of reaching deep in the airways. That wastes medicine and delivers an uncertain dosage."
Tajik led computer modeling that simulated how air moves through a child's airway and how inhaled particles travel to the mouth, throat and deeper lung tissue. The goal is to design inhalers that reduce how much medication gets stuck in the mouth and throat, increase how deeply particles penetrate the lungs, and still work when a young child or very sick patient can only inhale weakly.
To test the designs, researchers used a breathing simulator connected to a 3D-printed model of a child's airway.
"We tested both dry and wet surface versions of the airway to mimic real, moist human airways," Khalek said. "This helped us to see that moisture changes how deeply inhaled particles penetrate."
Dry powder inhalers use two components: a larger carrier particle and the much smaller drug particle. When particles are too small, users tend to exhale them. When they’re too big, they often won’t penetrate deeply into the lungs.
“The variability with inhalers can be significant and potentially dangerous: overdosing can lead to adverse effects while underdosing can make treatments ineffective,” said SwRI scientist James Oxley, who led the project's chemical engineering work.
The researchers say a more precise design could eventually make it possible to deliver more potent drugs that aren't currently suitable for inhalers due to dosing variability.
Data from Southwest Research Institute