The present invention relates to pharmaceutical compositions comprising a .beta. (1-3).beta. (1-4) glucan and a pharmaceutically active agent or a botanical extract. A method to extract and purify cereal .beta.-glucan is also described. The high purity of the cereal .beta.-glucan obtained according to the present invention allows for the preparation of clear, colourless viscous liquid preparations. These liquid preparations are stable to gelling effects when kept at ambient temperatures and low ash concentrations, and can be used to prepare the pharmaceutical compositions of the present invention.