Study of stability and drug-excipient compatibility of estradiol and pharmaceutical excipients

Abstract

Estradiol (E2) is the main drug used in menopause therapy. This study aimed to evaluate the drug-excipient compatibility of binary mixtures (BMs) (1:1 BMs, w/w), initially by differential scanning calorimetry (DSC), and subsequently, by complementary techniques such as X-ray powder diffraction (XRPD) and high performance liquid chromatography (HPLC) if there was any evidence of interaction. The samples were stored under accelerated stability conditions (40 °C at 75 % relative humidity). The DSC curves of estradiol and the BMs with excipients (corn starch, lactose, xanthan gum, microcrystalline cellulose, magnesium stearate, dibasic calcium phosphate, and talc) were obtained. The results show that estradiol was compatible with all the selected excipients. XRPD and HPLC analysis were instrumental in interpreting the DSC results and excluding relevant pharmaceutical incompatibilities in all cases. Overall, the compatibility of the selected excipients with estradiol was successfully evaluated using a combination of thermal and spectroscopic methods, and the formulations developed using the compatible excipients were found to be stable.