A combination drug containing niacin failed to lower the risk of heart attacks or strokes and even proved harmful for some with vascular disease, a study released Saturday reported.
Niacin, also known as vitamin B3, has for years been widely prescribed to lower "bad" LDL cholesterol and raise levels of "good" HDL cholesterol.
The link between high levels of LDL cholesterol and heart disease is well-documented, and doctors work to mitigate that risk with diet and lifestyle changes as well as a variety of medications.
But even with these protocols in place, heart disease and stroke claim lives and cause damage, so scientists continue searching for ways to improve the treatment.
Niacin -- in doses about 100 times higher than the recommended amount from food -- was thought to be helpful.
Indeed, the combination drug used in the study -- made by US pharmaceutical giant Merck and combining extended release niacin with laropiprant -- is already approved in 70 countries, though not the US.
But when tested against a placebo in more than 25,000 patients, it failed to reduce the numbers of heart attacks, strokes or other serious cardiovascular problems.
Even more worryingly, the study showed unexpectedly higher levels of bleeding and infections in the group taking the drug versus the placebo.
And the group taking the study drug also showed higher levels of other side effects, including new cases of diabetes and complications for previously-diagnosed diabetes, as well as rashes and diarrhea.
"We are disappointed that these results did not show benefits for our patients", said Jane Armitage, lead author of the study, which included more than 25,000 subjects.
But she and her fellow authors said the result is important, because it gives evidence that the risks of niacin outweigh the benefits when used with current treatments.
Armitage said it was unlikely the poor outcome could be linked to the second component of the drug, laropiprant, which was included to reduce the facial flushing caused by niacin.
The lack of benefit on heart attacks and strokes is consistent with another recent, smaller-scale study of niacin, which did not use laropiprant, and many of the side effects are known to be due to niacin, she explained.
Because of the results of this research, Merck has withdrawn its application for FDA approval of the drug and suspended its sale around the world.