A process for preparing Form A of (S) -5-methoxy-2 - [[(4-methoxy-3,5-dimethyl-2-pyridinyl) -methyl] sulfinyl] -1Hbenzimidazole magnesium dihydrate comprising crystallizing or recrystallizing the (S) -5-Methoxy-2 - [[(4-methoxy-3,5-dimethyl-2-pyridinyl) methyl] -1 H -benzimidazole magnesium dihydrate in the presence of ethyl acetate and in which the product of the Crystallization or recrystallization is filtered and washed with ethyl acetate.Un proceso para preparar la Forma A del (S)-5-metoxi-2-[[(4-metoxi-3,5-dimetil-2-piridinil)-metil]sulfinil]-1Hbenzimidazol magnésico dihidrato que comprende cristalizar o recristalizar el (S)-5-metoxi-2-[[(4-metoxi-3,5-dimetil-2- piridinil)metil]-1H-benzimidazol magnésico dihidrato bruto en presencia de acetato de etilo y en el que el producto de la cristalización o de la recristalización se filtra y se lava con acetato de etilo.
