Influence of extrusion-spheronization processing on the physical properties of d-indobufen pellets containing pH adjusters

d-Indobufen pellets containing pH adjusters (acids, buffer, salt) were prepared by extrusion-spheronization technology.
The interaction effect between some processing variables (feeding/agitator speeds of extruder, plate speed and residence time of spheronizer) was evaluated by comparing the basic formulation pellets with the pellets in which the soluble filler (lactose) was substituted by fumaric, tartaric and citric acids and also sodium citrate.
The criteria of formulation and process evaluation were the reproducibility of the particle size distribution, the density, the hardness and morphological properties, in addition to the reproducibility of the drug dissolution rates.
In all cases, the physical/technological characteristics were not influenced very much by pH adjuster incorporation, but the drug dissolution profiles showed some significant variations in the first hour. As a logical extension of this work, wet granulations with aqueous ethylcellulose and acrylic resin dispersions instead of only water were tested to evaluate the wetting effect of the release modifier inclusion. The results confirmed the validity of polymeric systems in the preparation of pellets and their ability to produce a further delay of d-Indobufen release.