Transdermal delivery of bioidentical estrogen in menopausal hormone therapy: a clinical review

Introduction: The history of menopausal hormone therapy (HT) use has evolved over the years based on the influence of many factors, including availability and safety related to formulation and route of estrogen products. Given unexpected findings from the Women's Health Initiative (WHI) in the early 2000's that used oral conjugated equine estrogen, the desire for and research supporting transdermal estradiol products grew. Transdermal estrogen is now a popular and commonly used formulation for treating menopausal symptoms. Many FDA approved products are available and preferred to custom compounded bioidentical products given superior consistency and safety standards.Areas covered: This review explores the history of transdermal estrogen products, as well as their pharmacodynamics. It also includes a detailed exploration of the advantages and disadvantages of different estrogen formulations with a focus on clinically useful information.Expert opinion: FDA approved transdermal estradiol products are the preferred formulation and route for HT, along with a progestogen for women with a uterus, given their efficacy and superior safety profile.