Stents are metal or plastic tubes used in heart surgeries to open the narrowed coronary arteries and keep them so in future. However, bare metal stents cause restenosis or narrowing of the artery again after few years.
Second- and third-generation drug-eluting stents counteract this problem, but can lead to clumping of blood platelets and clot formation near the stent. To overcome this problem, a team of researchers led by Han-Mo Yang, Seoul National University Hospital conducted a study on animals where stents used for heart surgery were coated by the drug phosphodiesterase type 5 (PDE 5) inhibitor. The drug was initially developed to treat high blood pressure and patient follow-ups revealed an additional benefit of improvement in erectile dysfunction.
The researchers observed a decline in platelet clotting by 30% and an increase in the activity of the enzyme protein kinase G (PKG). This enzyme is known to prevent thickening and narrowing of arteries after any injury such as stent placement. Placing a stent reduces PKG activity in the body but a stent coated with the drug can increase the activity of PKG enzyme and prevent thickening of the arteries after surgery.
“If these effects are reproduced in human clinical trials, it can be used to coat stents in future heart surgeries or given orally after a stent placement because the efficacy and safety of the drug have already been established for other purposes” explains Yang.