Comparative study of the stability of venlafaxine hydrochloride sustained-release pellets prepared by double-polymer coatings and hot-melt subcoating combined with Eudragit ® NE30D outercoating

The aim of this paper was to study the comparative stability of venlafaxine hydrochloride (VEN) sustained-release pellets prepared by double-polymer coatings and hot-melt subcoating combined Eudragit® NE30D outercoating. The uncoated VEN pellets, containing 45% (w/w) VEN, 45% (w/w) MCC (PH101), 10% (w/w) stearic acid and 0.5% (w/w) Carbopol974, were prepared by extrusion-spheronization. Satisfactory release profiles were obtained when VEN pellets were prepared by 4% EC subcoating combined with 4% Eudragit® NE30D outercoating and 8% hot-melt subcoating combined with 6% Eudragit® NE30D outercoating, respectively. The storage stability was monitored by measuring the drug release over six months storage at 40°C/75% RH and at room temperature (25 ± 2°C/60% RH). The release of pellets with double-polymer coatings increased markedly, while drug release of pellets prepared by hot-melt subcoating combined with polymer coating gradually decreased. Basically, the former may be attributed to the main role of drug mig...