Steroid release from silicone elastomer containing excess drug in suspension.

Abstract The in vitro release from a matrix consisting of silicone elastomer was studied for the purpose of testing release theories. The micronized steroid was suspended in silicone elastomer, and the release from a controlled surface area into an aqueous “sink” was experimentally determined. After a certain time period, the release from the matrixes displayed the predicted time and concentration dependencies. An initial period of apparent linear release was observed. The duration of this period was concentration and particle‐size dependent. The amount released assumed square root of time dependency after the initial linearity period terminated. The observed results are inconsistent with the equations developed to describe the release of solutes from ointment bases and matrix systems. The concentration and particle‐size effects on the duration of the linear release suggest that the release is dissolution rather than diffusion controlled.