Transdermal estradiol (TE) application (using gels, patches or a novel spray) is now a preferred route of hormone therapy (HT) in menopausal women, because various risks such as venous thromboembolism, stroke and unwanted hepatic effects can be reduced compared with oral HT. However, in the presence of an intact uterus, concurrent administration of progestogen is needed for endometrial protection. Due to the variety of progestogens available and differences in their clinical effects, the selection of the most appropriate substance and dosing for individual combination therapy can be difficult. This is especially true for TE gels and the novel spray because no fixed combination products are commercially available, meaning all progestogens must be added separately, and even for patches only two transdermal synthetic progestogens are available. The aim of this review was to summarize data on the endometrial effects of the different progestogens and to provide practical recommendations for the choice of progestogen (type and dosing), with a focus on endometrial protection when using TE, especially when using the novel estradiol (E2) spray.
Keywords: endometrial efficacy; endometrial histology; hormone therapy; progestogens; transdermal estradiol spray.