A pharmaceutical dosage form having a breaking strength of at least 300 N, said dosage form comprising:an opioid (A) selected from Oxymorphone, Oxycodone, Tapentadol, Hydromorphone, Hydrocodone, Morphine, and physiologically acceptable salts thereof wherein the weight content of the opioid (A) is from 5.0 to 35 wt.-%an anionic polysaccharide (B) selected from croscarmellose, carmellose, crosslinked carboxymethyl starch, carboxymethyl starch, and physiologically acceptable salts thereof wherein the weight content of the anionic polysaccharide (B) is within from 5.0 to 35 wt.-% anda polyalkylene oxide (C) having a weight average molecular weight of at least 200,000 g/mol wherein the weight content of the polyalkylene oxide (C) is from 20 to 80 wt.-%wherein all wt.-%s are based on a total weight of the dosage form, and the opioid (A) is present in a controlled-release matrix comprising the anionic polysaccharide (B) and the polyalkylene oxide (C).
