Purpose: This study was to design and evaluate effervescent floating tablets with sustained release behaviour. Pentoxifylline is a water-soluble model drug with a short half-life, consequently developing sustained release preparations would be beneficial. Methods: A binary (1:1) mixture of sodium alginate and hydroxyethyl cellulose containing pentoxifylline, with either 10% or 20% calcium carbonate or sodium carbonate, was used to prepare floating tablets. Results: Tablets floated on the surface of the dissolution medium, showed an adequate floating lag time, and floated for more than 12 hours. Tablets manufactured from granules with 20%(w/w) calcium carbonate were promising with respect to their floating lag time (similar to 7min), floating duration (>24 hours), sustained drug release rate, and swelling ability. An in vivo study of these promising tablets and a reference solution of pentoxifylline were investigated following oral administration of 5.75 +/- 0.15mg in rats. Compared with the reference solution, the pharmacokinetic parameters changed significantly (p<0.05); the C-max of the tablets was decreased (945.32ng/ml versus 2552.30ng/ml for the solution), while the T-max and t(1/2) were prolonged. Conclusion: The study shows that a binary mixture of hydroxyethyl cellulose and sodium alginate, together with 20%(w/w) calcium carbonate, offers an exciting opportunity to develop sustained release pentoxifylline preparations. (C) 2017 Elsevier B.V. All rights reserved.