The invention relates to an oral pharmaceutical dosage form providing resistance against dose dumping in aqueous ethanol and comprising a pharmacologically active ingredient embedded in a matrix material wherein the matrix material comprises an alkyl cellulose and a heteropolysaccharide and wherein the relative weight ratio of heteropolysaccharide to alkyl cellulose is within the range of from 1 : 20 to 20 : 1 and wherein the total content of alkyl cellulose and heteropolysaccharide is at least 35 wt. % relative to the total weight of the dosage form.
