Riboflabin release from hydrophilic matrices using Dome Matrix® technology

ALVARO FEDERICO JIMENEZ KAIRUZ; RUGGERO BETTINI,; SONVICO, F.; COMO, C.; STRUSI, O. L.; PAOLO COLOMBO,

Versalles, Fr.

Congreso; Conference on optimising drug delivery and formulation: Evaluation of drug delivery system issues and perspectives; 2005

Hydrophilic matrices prepared by direct compression, shaped as disc having concave and convex bases, were used as drug delivery modules in controlled release system (Dome Matrix® technology) [[1]]. When two modules were soldered with the concave bases facing each other, a void space inside the system was created resulting in a floating device (void configuration). An alternative assemblage was obtained by soldering two modules with the convex base inserted in the concave base (stacked configuration) from modules and systems. The aim of this work was evaluate the influence of the matrix composition and the shape on rate and kinetic of riboflavin release in order to obtain a gastroretentive formulation using the Dome Matrix® technology.Five series of modules were prepared using riboflavin as model drug and different proportions of HPMC K15M and K100LV as hydrophilic matrices: 100:0, 75:25, 50:50, 25:75 and 0:100 (total HPMC 40%, riboflavin 4%, lactose 45.8%, PVP 5%, PEG6000 5% and Mg stearate 0.2%). Modules were soldered using a Branson® ultrasound apparatus. In vitro release studies were performed using a USPXXVI dissolution apparatus 2, with 900ml of simulated gastric fluid at 37°C. The analysis of kinetic data was performed through the Ritger-Peppas equation [[2]] and the release rate was expressed in mean dissolution time (MDT).Different proportion of two HPMC allows modulation of riboflavin release rate between 100 and 985 min of MDT values. It could be observed a linear relationship between the HPMC K15M quantities in the formulation and the MDT calculated. The influence of the geometry on the release rate was assessed by comparing different Dome configuration containing the same composition. Results showed that release rate of Dome Modules > Void Configuration > Stacked Configuration.All release profiles obtained were linear. The diffusional values n were close to the unit confirming that matrix erosion is the main mechanism of drug release. Also, when n values of the 3 modules were compared a higher dependence on the formula composition was observed for Dome Modules.The assembled modules in Void Configuration were able to float immediately and for a prolonged time. The assemblage and the formulation composition of the modules produced a change in the release rate of riboflavin without changing the release kinetics. The erosion of the matrices is the principal mechanism that controls drug release. The assembled modules in Void Configuration is interesting for the development of gastroretentive drug delivery system. [1] COLOMBO P., BETTINI R., SANTI P., CATELLANI P.L. Modular systems for the controlled release of a substance with space and time control. BREVETTO PCT/EP02/12988, 20 novembre 2002. [2] RITGER P.L., PEPPAS N.A. A simple equation for description of solute release I. Fickian and non-Fickian release from non-swellable devices in the form of slabs, spheres, cylinders or disks. J. Controlled Release 5 (1987) 23-36.