Blocked polymeric particles having internal pore networks for delivering active substances to selected environments

摘要

A composition for the controlled release of an active substance comprises a polymeric particle matrix, where each particle defines a network of internal pores. The active substance is entrapped within the pore network together with a blocking agent having physical and chemical characteristics selected to modify the release rate of the active substance from the internal pore network. In an exemplary embodiment, drugs may be selectively delivered to the intestines using an enteric material as the blocking agent. The enteric material remains intact in the stomach but will degrade under the pH conditions of the intestines. In another exemplary embodiment, the sustained release formulation employs a blocking agent which remains stable under the expected conditions of the environment to which the active substance is to be released.