Melt extruded helical waxy matrices as a new sustained drug delivery system

The aim of this research was to prepare helical and cylindrical extrudates by melt extrusion and to evaluate their potential as sustained release dosage form. The systems contained theophylline as water-soluble model drug and microcrystalline wax as thermoplastic binder. The temperature suitable to ensure a successful extrusion process of formulations containing the wax in three different percentages was found to be below the melting point of the excipient. Then, the different systems were analysed from the in vitro dissolution point of view to study the influence of the shape and of the composition on the drug release. An in vivo pilot study on the best performing system (helix with 3 blades) was carried out on five healthy volunteers and monitoring the intestinal transit by X-ray images. The resulting plasma profiles were analysed by means of a suitable pharmacokinetic analysis. A mathematical model was developed to perform a description of in vitro and in vivo release.