An anti-clotting drug usually prescribed for hemophiliacs might increase heart attack risk even in those without the clotting disorder.

The drug is a genetically engineered form of factor VII, a key protein missing in some people with the hemophilia.

The drug may be prescribed off label to stop any excessive bleeding from stroke, trauma or surgery, though not authorized to do so.

Researchers reviewed 35 clinical trials on off-label use of the drug and have made a conclusion that risk of heart attack, or any complications associated to that doubled with the drug use.

Dr. Marcel Levi of the University of Amsterdam and his colleagues found more people between ages 65 and 75 getting affected. However, they noticed that risk of unwanted clots did not rise when the drug was used.

"The authors appropriately warn readers that these data warrant scrutiny when rFVIIa is used on an off-label basis," Aledort noted.

"This article should serve as a template for pharmaceutical companies to report all studies involving the use of a given drug, on-label and off-label, so that physicians can fully appreciate the benefit and risks when making therapeutic decisions."