ABSTRACTMatrix tablets containing paracetamol and hydroxypropyl methylcellulose (HPMC 2906) of different viscosity grades (50, 400, 1500, and 4000 mPa·s) were evaluated for drug release and change in matrix tablet mass [ΔM (%)] after exposure to 0.09, 0.15, 0.31, and 0.52M ionic strengths of dissolution media. At 0.09 and 0.15M ionic strength, drug‐release profiles reflected the extended release characteristic; in addition the increase in ΔM was slow and continuous within first few hours. At 0.31M the higher viscosity grade matrices showed extensive initial swelling and the loss of extended release whereas at 0.52M a similar tablet performance is observed for the matrices of all viscosity grades. Notably, when extensive increase in ΔM occurs in the very beginning of exposure to medium the loss of extended release from the matrix is expected. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43604.