The new diet drug - small benefit, much hype - Redux

Healthfacts, August, 1996

The drumroll has begun for Redux, the first weight loss drug to be approved by the FDA in 20 years. Soon to be published is the obligatory doctor-authored book, complete with breathless title. The Redux Revolution by Sheldon Levine, M.D., which has been rushed into print by William Morrow Publishing Company, appears destined for the best-seller list.

And Wyeth-Ayerst, the manufacturer of Redux (chemical name: dexfenfluramine), recently announced plans to sponsor an education initiative to raise awareness about the seriousness of obesity among physicians and the general public. (As if most of the general public were not already obsessed with excess weight.)

Don't expect an objective opinion on Redux from registered dieticians. Wyeth-Ayerst has started a program with the American Dietetic Association to match dieticians with physicians who prescribe Redux. The ADA's July newsletter gushes in anticipation of the thousands of new referrals for its members...thanks to an agreement with Wyeth Laboratories. An 800 number for dietician referrals will be given to physicians by the Wyeth sales representatives as part of their Redux sales pitch.

Before we get to the specifics such as how much weight loss, a look beyond the hype is in order. Redux isn't exactly a new drug. It has been marketed in more than 65 countries. Furthermore, Redux is a variation on another diet drug, fenfluramine, which has been available in the U.S. since the 1970s, and it is chemically similar to the popular antidepressant, Prozac. But fenfluramine (brand name: Pondimin) never really took off until a few years ago when a study showed a weight loss benefit if combined with another drug, Ionamin.

No Comparison Studies

What is Redux's advantage over this older drug combination? We don't know because no researchers have compared Redux against the Pondimin-Ionamin combination in a clinical trial. As with all new drugs, Redux was compared with a placebo as required by the FDA. The manufacturer has no incentive to compare its new drug against old ones. What manufacturer wants to find out that its new drug isn't an improvement? Interestingly, Pondimin is owned by a division of Wyeth-Ayerst's parent company, American Home Products.

Redux does not eliminate the need to diet. It has been tested and proven beneficial to people who are obese, which is defined as 20-30% or more over the ideal weight range. This is the level at which excess weight is associated with serious medical conditions. Redux was approved--and note the careful wording--as an aid to diet for the treatment of obesity and maintenance of weight loss. But many obesity specialists have expressed concern that physicians will prescribe the drug to the merely overweight, as opposed to the obese.

Now for the question of how much weight loss. The FDA's approval rested largely on the results of a study of 822 obese people on a reduced-calorie diet; half took 15-mg Redux capsules daily and half took a placebo. The drug's effects were modest. After one year, the people taking Redux lost an average of 22 pounds and those on the placebo lost an average of 16 pounds. The losses peaked at six months and were maintained better in the Redux-treated group which remained on the drug to the end of the study (The Medical Letter, 19 July 1996).

Unimpressive Results

Two smaller studies cited by The Medical Letter showed unimpressive results. A one-year study of only 36 dieting obese people found no significant difference in weight loss between the placebo-treated and the Redux-treated. A six-month study of 60 dieting obese people showed the Redux-treated people lost twice as much as the placebo takers, but five months after stopping treatment, there was no difference in weight loss between the two groups.

Only one study of people on the Pondimin-Ionamin therapy was cited in The Medical Letter. Dieting people taking this combination did lose weight, but, over the course of three years, many gradually regained weight despite continuing the drugs. (Redux costs $2 a day which is only slightly more than the cost of combination therapy.)

The known side effects are minor, for example, dry mouth, drowsiness, and diarrhea, but Redux (and Pondimin) also holds the rare possibility of causing an often fatal condition called primary pulmonary hypertension. Since the study to support the drug's approval lasted only a year, no one knows whether the weight loss can be sustained after stopping the drug or whether it is safe to continue.

The mechanism of action for Redux has some experts concerned about potential mood-altering effects because the drug increases the amount of serotonin, a substance involved in transmitting signals between brain cells. The drug prevents the brain's available amount of serotonin from being broken down, which in turn signals the cells to produce more. In animal studies increased transmission of serotonin suppresses appetite. A similar action occurs with Prozac, which results in weight loss in some people taking this drug for depression.