June 22 (Reuters) - The U.S. Food and Drug Administration approved Medicines Co's (MDCO.O) blood clot preventer Cangrelor on Monday, close to a decade after the drug first entered late-stage studies.

Cangrelor is an intravenous threpay aimed at preventing blood clots in patients who need percutaneous coronary intervention (PCI) or angioplasty - a non-surgical procedure to widen narrowed or obstructed arteries or veins using stents.

Cangrelor is a P2Y₁₂ inhibitor under investigation as an antiplatelet drug^[1] for intravenous application. Some P2Y₁₂ inhibitors are used clinically as effective inhibitors of adenosine diphosphate-mediated platelet activation and aggregation. Unlike clopidogrel (Plavix^®), which is a prodrug, cangrelor is an active drug not requiring metabolic conversion.Poor interim results led to the abandonment of the two CHAMPION clinical trials in mid-2009. The BRIDGE study, for short term use prior to surgery, continues. The CHAMPION PHOENIX trial was a randomized study of over 11,000 patients published in 2013. It found usefulness of cangrelor in patients getting cardiac stents. Compared with clopidogrel given around the time of stenting, intravenous ADP-receptor blockade with cangrelor significantly reduced the rate of stent thrombosis and myocardial infarction. Reviewers have questioned the methodology of the trial.