The Influence of Drug Solubility and Particle Size on the Pellet Formulation in a Rotoprocessor

Abstract

Pellets containing drugs of different properties were prepared in a Rotoprocessor in order to study changes in the formulation process and resulting pellet characteristics. Diltiazem hydrochloride, diclofenac sodium, and theophylline were chosen as model drugs. Pellet size distribution, sphericity, density, hardness, friability, and repose angle were determined using standard methods. The amount of water as a wetting agent necessary for successful pellet formulation was observed for each sample and changed depending on drug solubility, concentration, and particle size. The pelletization of freely soluble diltiazem hydrochloride required 24.8-23.1% of the wetting agent and its amount decreased as the drug concentration increased. The demand for water in the formulation of theophylline pellets was 31.0-34.4% and it increased with increasing drug concentration. The pellet samples containing both drugs were easy to prepare. However, the cohesion of micronized diclofenac sodium particles negatively influenced both the pellet size distribution and the formulation process itself. When the drug concentration exceeded 40%, it was not possible to produce pellets of an appropriate size and the process was not reproducible.

Multiparticulate systems containing 5-aminosalicylic acid for the treatment of inflammatory bowel disease

“…Particles of homogeneous matrix structure and drug content of 65% can be obtained. Their particle size distribution is however broader than that resulting from the above mentioned two methods 70,71 . Spray drying is a method of converting solution or suspension droplets into porous spherical particles by hot air in a production chamber.…”