Merck's Anti-Clot Drug 'Zontivity' Gets FDA Approval

Merck's clot preventing drug, Zontivity or vorapaxar, is now approved by the U.S Food and Drug Administration.

Zontivity belongs to a group of drugs called protease-activated receptor-1 (PAR-1) antagonist. It works by decreasing the tendency of blood platelets to clump together. The drug is aimed at reducing the risk of a second heart attack.

A major adverse reaction of the drug is that it increases risk of bleeding. Indeed, any drug designed to prevent blood clots up bleeding risk.
Zontivity's approval had been delayed over safety concerns about the increased chances of bleeding, Reuters reported.

In fact, two large clinical trials had earlier shown that the drug carried an unacceptably high risk of serious and sometimes, fatal bleeding, However, a new analysis of one of those trials, the TRA2P trial showed that vorapaxar could be used along with other drugs to reduce the risk of heart attack, stroke, Forbes reported. The drug can also reduce the need for procedures to restore blood flow to the heart.
The drug carries a Boxed Warning to alert health care practitioners about possible side-effects. People who have had stroke or bleeding in the head, FDA said in a statement.

"In patients who have had a heart attack or who have peripheral arterial disease, this drug will lower the risk of heart attack, stroke, and cardiovascular death. In the study that supported the drug's approval, Zontivity lowered this risk from 9.5 percent to 7.9 percent over a 3-year period - about 0.5 percent per year," said Ellis Unger, M.D., director of the Office of Drug Evaluation I in the FDA's Center for Drug Evaluation and Research, according to a news release.
Safety and efficacy of the drug was tested during clinical trials that included 25,000 people. Researchers found that Zontivity plus other anti-platelet agents (generally aspirin and clopidogrel) reduced risk of heart attack or stroke when compared to placebo.