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 migration into the EC subcoating, and the latter may be caused by the fusion and resolidification of stearic acid particles and the further aging of the Eudragit(®) NE30D outercoating. In summary, regardless of the change in release, drug dissolution met the standard requirement and the stability was acceptable during the storage period.