SILVER SPRING, MD, 28 June 2007 — Members of FDA’s Endocrinologic and Metabolic Drugs Advisory Committee in June agreed unanimously that rimonabant, a weight-management drug made by Sanofi Aventis, lacks adequate safety data to merit FDA approval.
“I wouldn’t in any way suggest that it be approved at the present time for use,” said committee member Jules Hirsch of Rockefeller University in New York.
Rimonabant is a selective cannabinoid-1 (CB-1)-receptor inhibitor and would have been the first in this class of drugs available in the United States. The drug inhibits the body’s endocannabinoid system, which affects appetite, energy balance, glucose and lipid metabolism, and body weight.
Rimonabant is already approved for sale in nearly 40 countries under the brand name Acomplia but would be called Zimulti in the United States, according to Sanofi Aventis.
When accompanied by a low-calorie diet, rimonabant led to significantly greater weight loss than placebo during clinical trials. Most of the weight loss occurred during the first nine months of therapy before leveling off and was accompanied by improvements in waist circumference and plasma levels of triglycerides and high-density-lipoprotein cholesterol.
Although FDA stated that the weight loss from rimonabant was clinically and statistically significant, the agency expressed concerns about rimonabant’s safety profile—in particular, the neurologic and psychiatric adverse events that were frequently reported in clinical trials of the drug.
Amy Egan, an FDA medical officer, told the panelists that adults who received a once-daily 20-mg dose of rimonabant, the amount effective for weight loss, were about twice as likely as placebo recipients to report psychiatric effects such as depression, anxiety, suicidality, and other cognitive and neurologic symptoms.
“The vast array of these events gave us a considerable sense of uneasiness,” Egan said, adding that rimonabant recipients were more than twice as likely as placebo recipients to drop out of clinical trials because of psychiatric symptoms.
Patients with a significant history of depression were excluded from clinical trials of rimonabant, even though overweight and obese people are believed to be at great risk for depression.
Egan said that 8.5% of rimonabant recipients began taking an anxiolytic or hypnotic and 4.8% began antidepressant treatment during clinical trials—roughly double the percentages who initiated these therapies while taking placebo. She noted that 88% of participants in the major rimonabant trials who reported neuropsychiatric symptoms while receiving the drug had no prior history of depressive symptoms.
Sanofi Aventis had proposed creating a risk-management program for rimonabant in the United States to prevent people with depression from taking the drug.
After the meeting, the manufacturer released a statement saying that it planned to work closely with FDA to resolve the committee members’ concerns about rimonabant.
An FDA decision on rimonabant is expected on July 27. Although FDA is not required to take the committee’s advice and reject the manufacturer’s application, the agency usually follows the recommendations of its experts.
Shannon Finks, a cardiology specialist and assistant professor at the University of Tennessee College of Pharmacy in Memphis, said the meeting’s outcome was “a big disappointment for the 60% of all Americans who are overweight or obese that could benefit from cardiometabolic risk reduction.”
“I had high hopes for this agent,” she said. But, she added, “I am certain that the advisory panel—hearing, seeing, and analyzing all data—made the right decision at this time to keep patients out of harm’s way.”
Finks, whose practice site is the Memphis Veterans Affairs Medical Center, is especially interested in the treatment of metabolic syndrome, a condition that is characterized by abdominal obesity, abnormal plasma triglyceride levels, and insulin resistance.
“Sixty percent or [more] of our patients are overweight,” Finks said. “We deal with the complications of being obese and having metabolic syndrome every single day.”
Sanofi Aventis had initially sought FDA’s approval to market rimonabant for the treatment of metabolic syndrome, according to FDA, but the agency stated that clinical data on the drug did not adequately support that indication.
Finks said that losing just a little bit of weight can improve patients’ cardiometabolic risk profiles.
“If you lose 5–10% of your body weight, we know that lipid parameters improve, we know that blood pressure decreases, we know that triglycerides decrease,” Finks said. “We know that you have an overall improvement in health.”
But Finks emphasized that neither rimonabant nor any other weight-loss drug should be the cornerstone of a program to help people lose weight.
“Lifestyle modification is the number-one treatment for metabolic syndrome and obesity,” Finks said. “Pharmacotherapy is not the answer. Pharmacotherapy can be used, though, with diet and exercise.”
Amy Franks, assistant professor at the University of Arkansas for Medical Sciences College of Pharmacy in Little Rock, emphasized that health care practitioners need to view weight management as a lifelong issue.
“We should be thinking about obesity as a chronic illness and treating it with the same vigor that we treat someone who’s hypertensive or someone who has diabetes or someone who has hyperlipidemia,” she said.
Franks, who recently completed a pilot study of a pharmacist-run program to identify and counsel adults with metabolic syndrome, said she is not a big proponent of pharmcotherapy for most patients.