Substantially pure 3-(3-indolyl)propionic acid free acid is synthesized by converting the free acid to 3-(3-indolyl)propionic acid calcium salt (3-IPA calcium), precipitating and washing, and then reconverting the 3-IPA calcium to the free acid. 3-IPA calcium is suitable for use in pharmaceutical compositions in tablet and sustained-release dosage forms. 3-IPA calcium can be used to inhibit the cytotoxic effects of amyloid beta protein on cells, to treat fibrillogenic diseases in a mammal, and to treat diseases or conditions in which free radicals or oxidative stress plays a role.
