New details from two studies reveal more side effects from niacin, a drug that hundreds of thousands of Americans take for cholesterol problems and general heart health. Some prominent doctors say the drug now seems too risky for routine use.
Niacin is a type of B vitamin long sold over the counter and in higher prescription doses. Some people take it alone or with statin medicines such as Lipitor.
Introduced in the 1950s, the drug hadn't been rigorously tested until recent years when makers of prescription versions were seeking market approval.
The two studies were testing prescription versions of niacin, and the bottom line -- that it didn't help prevent heart problems any more than statins alone do -- has already been announced. Those details are in this week's New England Journal of Medicine.
Heart specialists stress that patients never should stop taking any medicine without first talking with their doctors. Many have shied away from niacin since the initial results came out.
more than 700,000 prescriptions for various niacin drugs are written each month in the U.S. The top brand is Abbott Laboratories' Niaspan, which had nearly $900 million in sales in the U.S. alone last year, according to IMS Health, a health data firm.
The larger of the two studies tested Tredaptive -- a Merck & Co. combo of niacin and an anti-flushing medicine -- in nearly 26,000 people already taking a statin. Full results confirm there was a 9 percent increase in the risk of death for those taking the drug -- a result of borderline statistical significance, meaning the difference could have occurred by chance alone, but still "of great concern," Lloyd-Jones wrote in a commentary in the medical journal.
The drug also brought higher rates of gastrointestinal and muscle problems, infections and bleeding. More diabetics on the drug lost control of their blood sugar, and there were more new cases of diabetes among niacin users.
The initial results in December 2012 led Merck to stop pursuing approval of Tredaptive in the U.S. and to tell doctors in dozens of countries where it was sold to stop prescribing it to new patients.
Prompted by that study, leaders of an earlier one that tested a different niacin drug, Niaspan, re-examined side effects among their 3,414 participants and detailed them in a letter in the medical journal.
Besides more gastrointestinal, blood-sugar and other complications, the new report details a higher rate of infections and a trend toward higher rates of serious bleeding.
The consistency of the results on studies testing multiple types of niacin "leaves little doubt that this drug provides little if any benefits and imposes serious side effects," said Yale University cardiologist Dr. Harlan Krumholz.
"It's an astonishing reversal of fortune" for niacin, one of the very earliest cholesterol treatments, he said. "This is a billion-dollar drug and it never really had the evidence to warrant that sort of blockbuster status."
The studies were on prescription niacin; risks and benefits of over-the-counter forms are unclear.
Lloyd-Jones said niacin still may be appropriate for some people with very high heart risks who cannot take statins, and for people with very high triglycerides that can't be controlled through other means.
Krumholz said patients should talk with doctors about other treatment options besides niacin.
"This drug can hurt you," he said.
Niacin study: http://www.nejm.org/doi/full/10.1056/NEJMe1406410
Cholesterol guidelines: http://bit.ly/1j2hDpH
Cholesterol info: http://tinyurl.com/2dtc5vy
Heart facts: http://circ.ahajournals.org/content/127/1/
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP