Despite the lack of studies, Anchors discounts the potential for side effects similar to those encountered by phen-fen users. Arguing in his book that, since its introduction in 1987, Prozac has been connected to only eight instances of PPH out of 19 million users worldwide, he surmises that the differences in the way Prozac and fenfluramine affect serotonin levels account for the prevalence of cardiac effects in phen-fen users. But even Anchors can't be sure.
Although controlled studies are already underway to determine the actual cause of the cardiac effects, results are months, if not years, away. American Home Products, through its subsidiary Wyeth-Ayerst Laboratories, manufacturer of the withdrawn drugs, has already begun a clinical trial aimed at targeting the cause of the valvular damage.
Nutri/System's nationwide campaign to boost sales of phentermine(Drug information on phentermine)/Prozac combinations, without waiting for the hard, scientific data, according to Thomas Wadden, Ph.D., professor of psychology and psychiatry at the University of Pennsylvania School of Medicine, is "terribly irresponsible." Wadden, also director of the school's weight and eating disorders program, provided some of the subsequent data the FDA used to justify withdrawing fenfluramine and dexfenfluramine from the market. Rather than marketing a new, largely untested product, he said, Nutri/System ought to be giving echocardiograms to customers who got their phen-fen through its weight loss programs.
When Stanley Hertz, M.D., director of the eating disorders center at Schneider's Children's Hospital, at the Long Island Jewish Medical Center, first heard of the Mayo Clinic results at a Harvard conference over the summer, he immediately stopped prescribing the phentermine/Prozac combination.
"We don't know what the pathogenesis of the cardiac effects are of serotonin agonist medications and phentermine. So I, in good conscience, could not see giving it to patients...I took all of my patients off of it three months ago," Hertz said. "What is the mechanism that causes the cardiac effect? I would rather be conservative and do nothing from a lack of knowledge than be cavalier and do something."
The American Medical Association has also taken a cautious approach; acknowledging the physician's right to prescribe Prozac and phentermine for uses they deem appropriate, but at the same time warning doctors that there should be separate indications for each drug. If there were reasons to prescribe phentermine and Prozac to a single individual, for instance to treat obesity and depression, then the AMA would support it, said John C. Nelson, M.D., an AMA trustee. "But the combination of the two for weight loss we couldn't support. The reason we couldn't support it is because there's no clinical evidence for that...no studies done."
Nutri/System's marketing plan has its risks. Already, more than 100 lawsuits have been filed by individuals claiming injuries from phen-fen, and there are likely to be substantially more. Estimates are that the potential claims could reach over $3 billion as lawsuits spread beyond the manufacturers of phen-fen and Redux, to distributors, weight loss companies and physicians. DiBartolomeo declined to respond to questions regarding potential liability issues, including those claims asserted by Eli Lilly in its letter, despite numerous requests.
Four years ago, Nutri/System entered into a consent decree with the Federal Trade Commission (FTC) after it charged several weight loss firms with deceptive advertising by making unsubstantiated weight-loss and weight-loss maintenance claims. By the terms of the settlement, Nutri/System agreed not to misrepresent the performance or safety of any future weight-loss program, and was required to have scientific data to back up future claims about weight loss and maintenance.