This paper describes the preparation and characterization of a versatile Losartan-controlled-release material based on a functionalized cellulosic matrix grafted with the ionic liquid, [(MeO)3Sipmim][Cl]: 1–(trimethoxysilylpropyl)–3–methylimidazolium Chloride. A silanized ionic liquid was used as a solvent and a surface modification agent at the same time, allowing higher anionic drug loading capacity. The anionic Losartan drug release kinetics were evaluated as a model. The Losartan release was made using two distinct media, one at pH 7.4 and the other at 3.0 to simulate blood and stomach pH, respectively. Higher Losartan release-rate 88% at blood pH after 1085 min in comparison with 84% at stomach pH, after 330 min was attained. The higher Losartan release profile in acid pH compared with neutral pH could be associated to the hydrolysis of Si-O bond from the ionic liquid, with the acidic medium acting as a catalyst. This cellulosic matrix modified with ionic liquid showed promising for applications over a wide range of pH-controlled-release systems.