Study of gel-forming properties of sucrose esters for thermosensitive drug delivery systems.

Sucrose esters (SEs) are non-toxic, biodegradable, non-ionic surfactants. They have a wide range of hydrophilic-lipophilic balance values (1-16) and are usually applied as surfactants, or as solubility or penetration enhancers. The aims of this work were to study the gelling behaviour of SEs and the effects of this property on drug release. The gelling characteristics of two different SEs (P1670 and S970) were investigated by rheological measurements, and compared with each other. The effects of the gel-forming SEs on model drug (paracetamol) release were evaluated by in vitro drug release studies. The kinetics of the dissolution process were studied by analysing the dissolution data through the use of various kinetic equations. The results revealed that the gelling of the SEs is temperature- and concentration-dependent. The examined sucrose stearate (S970) has a stronger gel structure than that of sucrose palmitate (P1670) and this behaviour has a significant effect on the drug release. The analysis of the dissolution kinetic data in this study revealed that the dissolution follows the Korsmeyer-Peppas (paracetamol-P1670) or Higuchi (paracetamol-S970) equations.