Inert monolithic device with a central hole for constant drug release

In vitro drug release from inert monolithic matrices is generally characterized by a non-linear profile. This paper examines the release of drugs from a heterogeneous insoluble matrix which was designed to obtain an in vitro constant release. This matrix system, which shows a special geometry, consists of a biconvex perforated inert core that is partially covered with a water impermeable polymeric film so that the inner hole surface is the only releasing surface. Both the tabletting of perforated cores and their partial coating can be performed under continuous operating processes. This makes the system suitable for industrial applications thus differentiating it from all previous geometry-based inert systems. The release rate from this kind of device proved to be constant, irrespective of drug solubility, at up to 80% of delivery.