The invention relates to polysiloxanes contained as defoaming agents, amongst other things, in medicinal compositions such colon cleansing solutions and antiflatulants. The aim of the invention is to further improve the defoaming effect of polysiloxanes and also the compatibility of the agents. According to the invention, the use of calcium sulphate increases the defoaming effect of dimeticon or simeticon as polysiloxane defoaming agents. The invention also relates to PEG-containing colon cleaning solutions based thereon.
