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
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.
[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