A solid pharmaceutical composition in the form of a single dosage unit for oral use, the composition comprising a first and a second fraction, the first fraction comprises a therapeutically and/or prophylactically active substance dispersed in a dispersion medium that is sufficiently fluid at body temperature and the second fraction comprises a matrix comprising a substantially water soluble and/or crystalline polymer or a mixture of substantially water soluble and/or crystalline polymers, the first fraction being included in the composition in such a manner that at least a part of the second fraction is firstly exposed to the gastrointestinal fluids upon administration before the first fraction becomes exposed. The system is designed to release the active substance after a predetermined period of time after administration, and the release of the active substance at that point in time is relatively fast.