The present invention is based on the discovery that a marked increase in aqueous stability (and thereby shelf life) of prostanoid agonist prodrug compositions is achieved by incorporating into the compositions certain well defined carboxylic acids and thereafter adjusting the pH of the compositions from about 4.0 to about 8.0. As a result the compositions and methods of the invention provide the aqueous stability required for marketable topical drug treatments of a wide variety of ocular disorders.
