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Computational model offers insight into mechanisms of drug-coated balloons
CAMBRIDGE, Mass.—As noted by the Massachusetts Institute of Technology (MIT), the past few decades have seen scientists develop many devices that can reopen clogged arteries, including angioplasty balloons and metallic stents. While generally effective, each of these treatments has drawbacks, including the risk of side effects. A new study from MIT, however, analyzes the potential usefulness of a new treatment that combines the benefits of angioplasty balloons and drug-releasing stents, but may pose fewer risks.
With this new approach, a balloon is inflated in the artery for only a brief period, during which it releases a drug that prevents cells from accumulating and clogging the arteries over time. While approved for limited use in Europe, these drug-coated balloons are still in development in the United States and have not received U.S. Food and Drug Administration (FDA) approval. The MIT study, which models the behavior of the balloons will, it is hoped, help scientists optimize their performance and aid regulators in evaluating their effectiveness and safety.
"Until now, people who evaluate such technology could not distinguish hype from promise," said Elazer Edelman, the Thomas D. and Virginia W. Cabot Professor of Health Sciences and Technology at MIT and senior author of the paper describing the study, which appeared online recently in the journal Circulation. The lead author of the paper is Vijaya Kolachalama, a former MIT postdoc who is now a principal member of the technical staff at the Charles Stark Draper Laboratory.
In 2003, the FDA approved the first drug-eluting stent for use in the United States, which releases drugs that prevent cells from clumping in the arteries. Drug-eluting stents are now the primary choice for treating blocked arteries, but they also have side effects: The drugs can cause blood to clot over time, which has led to death in some patients. Patients who receive these stents now need to take other medications, such as aspirin and Plavix, to counteract blood clotting.
Edelman's lab is investigating a possible alternative to the current treatments: drug-coated balloons. "We're trying to understand how and when this therapy could work and identify the conditions in which it may not," Kolachalama said. "It has its merits; it has some disadvantages."
The drug-coated balloons are delivered by a catheter and inflated at the narrowed artery for about 30 seconds, sometimes longer. During that time, the balloon coating, containing a drug such as Zotarolimus, is released from the balloon. The properties of the coating allow the drug to be absorbed in the body's tissues. Once the drug is released, the balloon is removed.
In their new study, Kolachalama, Edelman and colleagues set out to rigorously characterize the properties of the drug-coated balloons. After performing experiments in tissue grown in the lab and in pigs, they developed a computer model that explains the dynamics of drug release and distribution. They found that factors such as the size of the balloon, the duration of delivery time, and the composition of the drug coating all influence how long the drug stays at the injury site and how effectively it clears the arteries.
One significant finding is that when the drug is released, some of it sticks to the lining of the blood vessels. Over time, that drug is slowly released back into the tissue, which explains why the drug's effects last much longer than the initial 30-second release period.
"This is the first time we can explain the reasons why drug-coated balloons can work," Kolachalama noted. "The study also offers areas where people can consider thinking about optimizing drug transfer and delivery."
In future studies, Edelman, Kolachalama and colleagues plan to further examine how blood flow affects drug delivery. They also plan to study a variety of different drugs and drug coating compositions, as well as how the balloons behave in different types of arteries.
The U.S. National Insitutes of Health and Abbott Vascular funded the research.
SOURCE: MIT News Office