Hydrophilic matrices as carriers in felodipine solid dispersion systems

Abstract

Hydrophilic matrices or hydrocolloids are polymers which swell on contact with aqueous solutions and dissolve slowly from the surface forming a gel mass. Several studies have been carried out in the past few years on the use of hydro-colloids in controlled release formulations. The present study used three modified celluloses, carboxymethyl cellulose sodium, hydroxyethyl cellulose (HEC), and hydroxypro-pylmethyl cellulose (HPMC) in systems using the dihydropyridine felodipine, which is slightly soluble in water, as the active ingredient. This study was concerned with solid dispersions, which were prepared following the dissolution method using a common solvent. The drug—polymer interactions were studied using differential scanning calorimetry and IR techniques, as well as high-performance liquid Chromatographic purity after storage in strength conditions. Neither significant interactions nor degradation of the active ingredient was observed after storage at 40 °C for 3 months. In addition, felodipine release from the solid dispersion systems was studied and the factors influencing release, such as the drug—polymer ratio, interactions, and polymer properties were investigated. HPMC was observed to promote a more significant retard and a more linear release of the active ingredient than HEC. Finally, the natural mixtures presented a larger variation and high relative standard deviation values.