Coating stents with an erectile dysfunction drug may be the way forwards in treating stent patients, say researchers.
In a series of laboratory and animal studies, the drug reduced blood clots and prevented re-narrowing (restenosis) of the arteries after stent placement.
The preliminary research, which was carried out by Han-Mo Yang (Seoul National University Hospital) and colleagues was presented at the American Heart Association's Basic Cardiovascular Sciences 2017 Scientific Sessions.
If the effect is reproduced in human trials, the drug may be used to coat stents in future heart procedures or it may be given orally after stent placement.
Stents are metal or plastic tubes that help to keep coronary arteries open and prevent them from becoming narrow or blocked again. With traditional bare-metal stents, tissue growth within the artery can lead to restenosis.
Second- and third-generation drug-eluting stents counteract this problem, but they can lead to another problem, which is the clumping of blood platelets and clot formation nearby the stent. To prevent this, patients are prescribed an anti-clotting medication such as aspirin.
In Yang and team’s studies, the drug, which is a phosphodiesterase type 5 (PDE 5) inhibitor, was effective in preventing both restenosis and blood clot formation. In laboratory tests, it reduced platelet clotting by 30% and in animal studies, it triggered increased activity of an enzyme called protein kinase G (PKG).
This enzyme prevents artery walls from thickening after they are subject to injury – as they may be after a stent placement procedure. Such injury reduces the level of PKG activity in the artery, which leads to thickening of the artery and increases platelet clumping.
The drug was originally developed to treat high blood pressure and patient follow-up revealed that a side effect was improvement of erectile dysfunction. This is because the PKG enzyme is also highly expressed in the erectile tissue of the penis.
If clinical trials show that the drug reduces restenosis after stent placement, it could be used in the clinical setting right away because the medication is safe and already used in the real world for other purposes, Yang explains.