WASHINGTON - An FDA proposal released last week holds out the prospect of an additional two years of market exclusivity for newly approved drug products such as Interneuron Pharmaceuticals Inc.'s Redux dexfenfluramine whose active ingredient is a single enantiomer of fenfluramine, a previously approved racemate

FDA was prompted to revisit its policies in part by IPIC's dexfenfluramine, which was approved in April 1996 as a treatment for obesity. Dexfenfluramine was the first single enantiomer of a previously approved racemate to be approved in the U.S.