The paper reports results of the studies of sulfonamide tablets obtained by the incorporation in hydrophilic carrier (Cellulose ether). The rate of sulfonamide release was determined by the paddle method. The occurrence of physical and chemical interactions of sulfonamides and cellulose ethers in the solid phase was confirmed by X-ray diffraction and thermal (TG and DSC) studies. The influence of these interactions on the sulfonamide release from the tablets was analyzed.