Merck (NYSE:MRK) Shares Plunge on Vorapaxar News

News that Merck's (NYSE:MRK) latest hope for a blockbuster drug were dashed caused the share price of the company to plummet, as it appears Vorapaxar won't be used in as widespread way as hoped.

Vorapaxar, which is a blood-thinning drug, will no longer be used to evaluate victims of strokes, implying a much tighter number of uses and smaller number of patients to treat.

Studies will continue on patients who have had peripheral artery disease or heart attacks.

This is also a blow to the $41 billion price they paid for Schering-Plough, which Vorapaxar was the major products Merck was looking at when making a decision to pay that price for the company.

Merck's head researcher Peter Kim attempted to assuage shareholders' concerns over the reasoning behind the decision, saying, “It is likely that some will try to draw conclusions based on this information. However, it is important to keep in mind that we do not yet know the specific safety and efficacy results of the trials.”

That brought little comfort to shareholders, who punished the stock on Thursday. Historically, when a drug trial is halted, it's either for safety reasons or lack of effectiveness. Either way, it's not good news for Merck, and to attempt to make it look like it's something besides those two reasons is disingenuous at best.

Merck closed Thursday at $34.69, down $2.46, or 6.62 percent.