While the amount of the above-mentioned amorphous water-soluble compound (I) to be employed varies with, for example, kinds of the compound (I) and desired pharmacological effects and duration, it ranges, in terms of the concentration in the solution of a polymer in an organic solvent, from about 0.001% to 90% (w/w), more preferably from about 0.01% to 80% (w/w), especially preferably from about 0