After a long haul, Merck & Co’s Zontivity has become the first drug in the new protease-activated receptor-1 (PAR-1) antagonist class to be approved for marketing in the US.
The anti-platelet drug has been cleared by the FDA to reduce the risk of heart attack, stroke, cardiovascular death, and need for procedures to restore the blood flow to the heart in patients with a previous heart attack or blockages in the arteries to the legs.
Trials of the drug in patients suffering a heart attack or with peripheral arterial disease showed that vorapaxar was able to reduce the risk of heart attack, stroke and death from 9.5 per cent to 7.9 per cent over three years, according to the FDA.
Approval of vorapaxar was expected after an FDA advisory committee backed it earlier this year, although the prospects for the drug looked dim a couple of years ago when two studies raised questions about its safety, specifically an increased risk of intracranial haemorrhage (ICH) in patients with a history of stroke.
The FDA said vorapaxar will carry a boxed warning to alert prescribers about the risk of ICH, and stressed that the drug should not be used in patients who have a history of stroke or transient ischaemic attacks (TIA) or mini strokes.
Originally developed by Schering-Plough – which Merck acquired in 2009 – vorapaxar had been tipped as a potential $5bn-a-year product before the safety issues emerged.
Now, its sales prospects are considerably more modest with some analysts predicting sales well below $500m a year given the risk:benefit ratio and competition in the marketplace from other antiplatelet drugs such as AstraZeneca’s Brilinta/Brilique (ticagrelor) and Daiichi Sankyo/Eli Lilly’s Effient (prasugrel) as well as generic clopidogrel.
Merck plans to launch Zontivity in the US in the coming weeks, while the PAR-1 antagonist is also under regulatory review in Europe for the same indication.