The present invention relates to a pharmaceutical formulation comprising the drug 4-[3-(4-cyclopropanecarbonyl--piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-phthalazin-1-one in a solid dispersion with a matrix polymer that exhibits low hygroscopicity and high softening temperature, such as copovidone. The invention also relates to a daily pharmaceutical dose of the drug provided by such a formulation. In addition, the invention relates to the use of a matrix polymer that exhibits low hygroscop-icity and high softening temperature in solid dispersion with 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-ben-zyl]-2H-phthalazin-1-one for increasing the bioavailability of the drug.