WASHINGTON, D.C. – The Food and Drug Administration (FDA) should not approve the new diet drug rimonabant (marketed as Acomplia in Europe and known as Zimulti in the U.S.) because it produces only modest weight loss and has been shown to produce serious physical and psychological adverse effects, according to Public Citizen testimony before an FDA advisory committee meeting today. The group argued that more extensive studies of the drug’s effectiveness and safety are needed to fully evaluate its benefit-to-risk ratio.

The testimony about rimonabant was prepared by Dr. Sidney Wolfe, Ben Wolpaw and Elizabeth Barbehenn, Ph.D., all of the Health Research Group at Public Citizen. Wolfe delivered the testimony to the FDA’s endocrine metabolic drugs advisory committee.

Rimonabant inhibits brain receptors involved in eating. But the drug also inhibits other areas of the brain and other organs, raising serious concerns about the drug’s toxicity.

Sanofi-Aventis, the maker of rimonabant, has claimed that in pre-clinical animal studies, the drug “was shown to have very limited potential to induce toxicity,” and that there was no specific organ pathology identified. Yet a report from the European drug regulatory authority acknowledges such adverse effects in animals as increased birth defects, impaired fetal survival, convulsions, liver toxicity, chromosomal aberrations and carcinomas.

“The elusive idea of a magic bullet drug that has a benefit mediated through its action on one receptor site, yet is devoid of risks at a myriad of other sites in the body, is once again exemplified by rimonabant,” said Wolfe. “Other such drugs – including Vioxx, Rezulin and Redux – were eventually removed from the market because of their toxicity.”

Because the receptors are widespread in the brain, rimonabant has been shown to cause extraordinarily broad kinds of psychiatric dysfunction, in addition to increased suicidal tendencies and other depressive symptoms. In clinical studies, patients given 20 milligrams of rimonabant showed significant increases in anxiety, insomnia and panic attacks, as well as increases in aggression and agitation compared to patients given a placebo. In addition, significantly more patients receiving rimonabant required a sedative, tranquilizer or an anti-depressant for adverse events caused by the drug.

“The evidence for increased suicidal tendencies and depression is of particular concern for a drug targeted toward the obese, a population that has been shown to have a significantly higher incidence of depression and eating disorders compared to non-obese individuals,” Wolfe testified.

Wolfe told the committee that another major issue with the drug is the lack of reliable information regarding the long-term effects of its use. Because patients regain weight lost while using rimonabant after they discontinue its use, the drug will have to be prescribed on a long-term basis to be effective. But of the studies performed to date, two lasted two years, while the other three were one year in length.

“Because rimonabant is the first drug of its class, there is no data on its use in humans over an extended period of time,” said Wolfe. “The complete lack of information about the long-term effects of this drug is a serious cause of concern.”

To read the testimony, click here.