Below is a brief excerpt from "Absorbable Stents" from the MedMarket Diligence report #C245, "Worldwide Drug-Eluting, Bare and Other Coronary Stents, 2008-2017."
The limitations of available metallic DES have created new interest in fully absorbable, fully biodegradable stents. The leading efforts in this area are sponsored by Abbott, Biotronik and REVA Medical. Only a handful of other companies are working on such a stent and none of the devices are approved for marketing in the United States or abroad.
With so much controversy surrounding standard DES, researchers (and investors alike) have readily turned toward development of devices that will reach beyond the benefits promised by standard DESs. As Dr. Serruys said at CRT 2007, “Abolition of neointimal hyperplasia is no longer the ultimate goal. Development of more biocompatible and bioabsorbable stents facilitating adequate endothelialization is expected in the near future.”
In the DES industry, the term “bioabsorbable” has been used interchangeably. In some cases, it has referred to the coatings on the stent and, in other cases, to the stents and coatings in their entirety, which degrade until nothing remains. These biodegradable stents prop open the vessel, some deliver an anti-restenotic drug and then, job completed, the stent dissolves and leaves behind a healthy vessel. However, one of the primary debates in regard to biodegradables is whether they will remain viable long enough to effect the necessary therapeutic benefit.
Within the biodegradable DES camp, there are polymers and metallics. Polymers have been utilized for their ability to dissolve promptly. However, studies conducted over the last couple of years show evidence that in some cases, bits of polymers may be left behind undissolved—and any rough surface in the vessel provides ready ground for restenosis.
There is also the question of whether polymers can provide optimum biological incompatibility. In experimental models, polymers have proven to incite a greater inflammatory reaction than inert materials. In addition, the biological response to a polymer is dependent on its formulation (including chemical structure and bulk load) and the time required for dissolution.
The complete coverage of the current and emerging global markets for absorbable, drug-eluting, bare metal and other coronary stents is provided in report #C245.