ETHEX 303 Pill with imprint ETHEX 303 is White, Elliptical / Oval and has been identified as Naproxen Enteric Coated 500 mg. It is supplied by Ethex Corporation. <span class=" fc-2nd">Aug 13, 2019 · </span> -Initial dose: 750 mg or 825 mg orally once on first day of attack-Following initial dose:...