Inhaler Provides Pinpoint Drug Delivery

Anyone who has played the old labyrinth game knows just how hard it is to tilt the board and move the ball through the maze while avoiding holes to get all the way to the goal. Now, imagine trying to do it without any knobs to control the ball’s direction. That’s the challenge presented by inhalers, according to Drs. Clement Kleinstreuer and Stefan Seelecke, who say getting medicine to a specific site in the maze of airways in the lungs is almost impossible without a way to control its direction.

Along with colleague Dr. Bill Roberts, the two Department of Mechanical and Aerospace Engineering professors have devised such a control mechanism, and they say their smart inhaler is the ideal way to deliver drugs to treat lung cancer, diabetes, and other diseases. Kleinstreuer came up with the idea after U.S. Environmental Protection Agency officials asked him to predict how particles of pollution would deposit in the lungs. An expert in fluid dynamics, he flipped the scenario to examine therapeutic materials instead of toxic ones and found that, by running simulations that backtracked from a specific site in the lungs, he could determine the exact place in the mouth where the materials were released.

Seelecke and Kleinstreuer then designed an inhaler with a tiny nozzle to disperse medicine in aerosol form from a single point. A valve inside the smart inhaler also matches the air flow to a patient’s breathing patterns for maximum efficiency in delivering the dose. Regular inhalers mix a wider spray of aerosol drugs and air, he says, so about 80 percent of the therapeutic particles land in the throat or along the initial branches of bronchial airways and never penetrate deep into the lungs. “The drugs wind up attacking healthy tissue in the lungs instead of treating a tumor or other disease,” Seelecke says. Using a series of twisting glass tubes to mimic the larynx and lungs and a laser to track the path of the particles, Roberts confirmed the findings of Kleinstreuer’s simulations by demonstrating that the spray from the nozzle could travel through at least three levels of branching airways in the lungs to a specific point.

Getting medicine to a specific site in the maze of airways in the lungs is almost impossible without a way to control its direction.

The researchers are planning a clinical test with pulmonary specialists at the UNC School of Medicine to test the smart inhaler in patients and are mapping regions in the lungs so the nozzle can be set to deliver targeted doses of medicine for individual patients. “Inhalation is becoming a more desirable way of bringing medication into the system,” Kleinstreuer says. “It’s a much more efficient and direct way than swallowing pills or injecting drugs.”



Drs. Clement Kleinstreuer, left, and Stefan Seelecke, center, fine-tune the design of their inhaler with Ph.D. student Matt Pausley.

Much of the medicine dispensed by a traditional inhaler, left, lands in the throat and airways. Studies show that the smart inhaler, right, targets the medicine so a concentrated dose is delivered to a tumor or a pre-determined site in the lungs.