Diet pill Meridia may garner new warning labels or be pulled from the market completely following today's meeting of the Food and Drug Administration's drug advisory committee.
In a vote this afternoon on the safety of the Abbott Laboratories' diet drug, panel members were split -- eight voted to boot the drug from the market while the remaining eight voted to keep it on the market with new safety restrictions.
Spurred by concern that Meridia might increase cardiovascular risk, Abbott Laboratories had sponsored a six-year trial, SCOUT, to further evaluate its safety, the results of which were reviewed today by the committee.
Now that results are in, it will be up to the FDA to consider the split decision and weigh whether the 16 percent increased risk in major adverse cardiac events seen in the trial is reason enough to restrict access or withdraw the drug from the U.S. market.
Given that patients on Meridia only lost five pounds more in the study than those on placebo, many doctors feel that this increased cardiovascular risk is simply not worth it.
"The key point here is that obesity itself is associated with increased risk of cardiovascular disease, so the rationale for prescribing obesity drugs is to improve outcomes [by lowering that risk]," says Dr. Kevin Niswender, assistant professor of medicine at the Vanderbilt University School of Medicine.
"A drug that is modestly successful at increasing weight loss but increases cardiac risk further, that's clearly an issue," he said.
Abbot Laboratories products containing Meridia's main ingredient, Sibutramine, were already pulled from the European market in January based on preliminary results from SCOUT.
SCOUT is a double blind placebo-controlled study that tested a 10 mg dose of Meridia plus diet and exercise in about 5,000 patients, comparing their side effects and weight loss to 5,000 control patients who followed diet and exercise and received a placebo pill.
Subjects were those with cardiovascular disease or type 2 diabetes who had not had a heart attack or stroke in the previous three months before starting the trial.
Though Abbot Laboratories expected its drug to decrease cardiovascular risk at the onset of the trial, the outcome six years down the road veered in the other direction.
"The SCOUT trial was powered on the assumption that sibutramine-related weight loss would reduce the relative risk for [major adverse cardiac events] by at least 15 percent. In contrast to this expected outcome, in an intent-to-treat analysis, the hazard ratio for [major adverse cardiac events] was 16 percent higher in subjects treated with sibutramine versus placebo," clinical reviewer of the trial, Dr. Monique Falconer, writes in the FDA briefing material on the drug.
What's more, it is possible that the study design may have underestimated the cardiac risks.
All subjects in the study underwent a six-week trial of the drug before starting the study. Some 900 subjects who had an immediate negative reaction to the drug, such as an increase in blood pressure or pulse rate, were thrown out of the study. The remaining subjects were randomized and used in the trial.