Controlled Release of Diclofenac by a New System Based on a Cellulosic Substrate and Calcium Alginate

Abstract

Promising controlled release systems were prepared from renewable natural products. Paper, used as the system core, was made with commercial kraft pulp and with bleached lignocellulosic pulps extracted from local plants. The characteristics of those pulps (fines content and fiber length) as well as paper thickness, porosity, and roughness, were evaluated. Alginate served as the protective membrane. The releasability of Diclofenac as a function of time and pH was studied under constant temperature (37 °C) and constant stirring (200 rpm). Also the influence of the type of paper and the calcium alginate concentration in the protective layer were highlighted. The extent of release reached 80% in a basic medium in a variable time interval 7 to 16 h, whereas in an acid medium it did not exceed 24% in 33 h. Diffusion, Fickian diffusion, and diffusion-erosion were judged to be important contributing mechanisms based on the Korsmeyer-Peppas kinetic model for those various matrixes. Different formulations were found to have significant controlled release properties that could be used in the prolonged release of the active ingredients. Because of the low release in acidic medium, the formulated system could be a good candidate to protect the active ingredient from acidic medium.

Keywords

• Alignate
• Controlled release matrix
• Cellulosic substrate
• Kinetic models
• Diclofenac