Stabilized benzimidazole derivative and composition

A composition containing a physiologically active amorphous benzimidazole derivative having the formula (I):

• ##STR6## wherein R.sup.1 is hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, a cyclohexyl group, phenyl group or a benzyl group, R.sup.2 is hydrogen atom or a lower alkyl group, or R.sup.1 and R.sup.2 together with the adjacent nitrogen atom form a piperidine, and each of R.sup.3a, R.sup.3b, R.sup.4a, R.sup.4b and R.sup.4c independently is hydrogen atom, a halogen atom, a flouroalkyl group having 1 to 6 carbon atoms, a lower alkyl group, a lower alkoxy group, a lower alkoxycarbonyl group or an amino group, dispersed in an organic polymer wherein the organic polymer is selected from the group consisting of hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose sodium, poly(vinylpyrrolidone), poly(vinyl alcohol), poly(sodium acrylate), sodium alginate, gelatin, gum arabic, .alpha.-starch, oxidized starch, heat-treated starch, enzyme-treated starch and agar and is contained in an amount of not less than 0.5 time as much as a weight of the benzimidazole derivative.