The release behavior of progesterone from a silicone matrix to release media containing 60% (v/v) alcohol and water was investigated and kinetically evaluated. For this purpose, samples containing 5, 10, or 15% (w/w) micronized progesterone were prepared through the mixing of two-component silicone and the drug in a thermomixer. The discs were cured with compression molding. Then, the release from a controlled surface area was experimentally determined by a high-performance thin-layer chromatography technique, a new method for progesterone analysis. With Higuchi's model, the drug-release behavior of the dispersion systems was determined by a partition-controlled process (the relationship between the accumulated amount of the drug released and the time) and a matrix-controlled process (the relationship between the accumulated amount of the drug released and the square root of time). The release profile determined by experimental data was in good agreement with Higuchi's model. Moreover, the product of the solubility and diffusivity of progesterone in the polymer matrix was evaluated and found to be 8.1 x 10(-7) mg/cm/s. Finally, the effects of fillers on the release behavior were studied. (C) 2004 Wiley Periodicals, Inc.