Dissolution behavior of 17β-estradiol (E₂) from povidone coprecipitates. comparison with microcrystalline and macrocrystalline E₂

The dissolution rates of macrocrystalline 17β-estradiol (E₂), microcrystalline E₂and E₂-povidone coprecipitates and physical mixtures varying in weight ratio from 1 : 1 to 1:49 were determined at 37°C. E₂ dissolution from the coprecipitates was markedly faster than that from either macro- or microcrystalline forms of the drug and was found to increase with decreasing E₂-to-povidone weight ratio. Based on the results of X-ray diffraction, differential scanning calorimetric. Raman spectroicopic, and thermal gravi metric analysis studies, it is concluded that the formation of a more water soluble, high energy state of E₂ is responsible for the increased dissolution rate of this natural cstrogen from low weight ratio povidone coprecipitates. These findings suggest that the use of E₂-povidone coprecipitates may increase the systemic availability of E₂.