Redux (dexfenfluramine hydrochloride)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.


Approval Status:

Approved May 1996

Specific Treatments:


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General Information

Redux, when combined with a reduced-calorie diet, has been indicated for the management of obesity, including weight loss and maintenance of that weight loss. The safety and effectiveness of Redux beyond one year have not been determined at this time.

Redux is recommended for obese subjects with an initial body mass index (BMI) of at least 30 kg/m2 (which is approximately 30% over desirable weight) or a BMI of at least 27 kg/m2 (which is approximately 20% over desirable weight) in the presence of other risk factors (e.g., hypertension, diabetes, or hyperlipidemia). Redux is available by physician's prescription in 15 mg capsules to be taken twice daily.

Clinical Results

In clinical trials, Redux therapy was associated with decreased appetite and may make people feel full and lessen their desire to eat.

In a large, one-year clinical trial of more than 900 subjects, individuals taking Redux in conjunction with a reduced-calorie diet loss significantly more weight than subjects on diet and placebo. Redux helped produce a significant reduction in weight during the first four to six months. This response was maintained during a year of therapy. At the end of the year, 64% of all subjects lost at least 5% of their initial total weight, 40% lost at least 10%, and 21% lost at least 15%. In a study of 60 obese subjects who had successfully lost weight by dieting alone (i.e., lost at least ten pounds in the previous year), the addition of Redux to their regimen resulted in the further loss of 26% of initial excess weight.

Side Effects

The most commonly reported side effects in clinical trials included drowsiness, diarrhea, and dry mouth. These side effects were usually mild and disappeared in a few weeks.

There is a low incidence of a serious, potentially life-threatening cardiovascular condition, primary pulmonary hypertension (PPH), associated with the use of all types of prescription weight loss drugs (anorexigens). A two-year study looked to investigate all incidences of PPH in Europe and identified 95 cases: 20 of these had been exposed to anorexigens in the past. Eighteen of the 20 cases identified a history of dexfenfluramine use. In an initial review of these cases (excluding ten additional cases where the specific drug or dates of use were unknown), the use of anorexigens for longer than three months was associated with a nine-fold increase in the risk of PPH. Therefore, the risk of PPH in obese subjects was estimated to be at least 18 cases per 1,000,000 subjects per year. The authors of the initial review are continuing to analyze the data. In the general population, the yearly occurrence of PPH is one to two cases per one million people.

Redux should not be used in subjects hypersensitive to dexfenfluramine or related compounds, in subjects with diagnosed pulmonary hypertension, or in subjects taking (or without 14 days of discontinuing) monoamine oxidase (MAO) inhibitors. Redux should not be administered to patients using other serotoninergic drugs. Redux is not recommended for women who are pregnant or nursing or for pediatric subjects.

Mechanism of Action

The mechanism of action of Redux is based upon its effects on serotonin, a neurotransmitter in the brain. Redux works primarily by decreased caloric intake associated with increased activity of serotonin in the brain.