Use of a water-soluble polymer having a solubility in water of greater than 5% (m/m) in the pH range of 1 to 13 and which is obtained by free-radically initiated polymerization of a monomer mixture of i) 70 to 90% by weight N-vinylpyrrolidone and ii) 10 to 30% by weight acrylic acid, wherein the sum total of i) and ii) corresponds to 100% by weight, for the formulation of basic active ingredients sparingly soluble in water, wherein the active ingredients in uncharged form or as hydrochloride have a solubility of less than 0.1% (m/m) in water, artificial intestinal juice or gastric juice.