The aim of this work was to evaluate water-soluble cellulose derivatives with tertiary amino groups for controlled drug delivery in artificial gastric juices, as well as in bowel medium. Acetylsalicylic acid and p-acetaminophen were used as model drugs of acidic and non-ionic character, respectively. Tablets were prepared containing 86% (w/w) of the drug, lactose, polymeric component and 1% of magnesium stearate as a lubricant. Lactose and cellulose derivative were used in equal ratio and both comprised 13% of the tablet weight. It was shown that the polymeric component contributes to achieving tablets of hardness sufficient for practical needs. Drug release from polymeric tablets in all cases was prolonged. Drug delivery was nearly linear. This indicates significant impact of tablet erosion on drug release. The acetylsalicylic acid release rate in artificial gastric juices depends on the content of the amino groups in cellulose. It is suggested that in the case of acidic active substances concomitantly with usual mechanisms, such as drug diffusion and polymer erosion, ionic interaction contributes to the drug release rate. (C) 2004 Elsevier B.V. All rights reserved.