Dexfenfluramine

Dexfenfluramine, marketed as dexfenfluramine hydrochloride under the name Redux, is a serotoninergic anorectic drug: it reduces appetite by increasing the amount of extracellular serotonin in the brain. It is the d-enantiomer of fenfluramine and is structually similar to amphetamine, but lacks any psychologically stimulating effects.

Dexfenfluramine was for some years in the mid-1990s approved by the United States Food and Drug Administration for the purposes of weight loss. However, following multiple concerns about the cardiovascular side-effects of the drug, such approval was withdrawn and it was retired from the market in 1997. After it was removed in the US, dexfenfluramine was also pulled out in other global markets. It was later superseded by sibutramine, which although initially considered a safer alternative to both dexfenfluramine and fenfluramine, was removed from the US market as well in 2010.

The drug was manufactured by Interneuron Pharmaceuticals, a company co-founded by Richard Wurtman, aimed at marketing discoveries by Massachusetts Institute of Technology scientists. In the case of Redux, Interneuron's manufacture was under licence to Wyeth-Ayerst Laboratories. Although at the time of its release, some optimism prevailed that it might herald a new approach, there remained some reservations amongst neurologists, twenty-two of whom petitioned the FDA to delay approval. Their concern was based on the work of George A. Ricaurte whose techniques and conclusions were later questioned.

In actuality, most conversant with the discussion felt that dexfenfuramine's only advantage was patent protection for its licensed companies. Racemic fenfluramine was far cheaper.