Transgender Estradiol

Blogs, word-of-mouth, and small studies from the 1990s in the premature ovarian insufficiency and menopause populations have suggested sublingual or transdermal estradiol may be safer and/or more effective than an oral formulation. Sublingual administration entails holding the estrogen tablet under the tongue and allowing it to dissolve, where its absorption is enhanced by the rich vascularization under the tongue. According to Price et al., sublingual administration results in rapid absorption with significantly higher estradiol levels than does comparable oral dosing. This is likely because sublingual administration will bypass metabolism by the intestines and liver. The transdermal route, which also bypasses first-pass metabolism, is not associated with an increased venous thromboembolic risk nor a significant increase in plasma triglycerides or HDL-cholesterol levels. As such, transdermal estrogen is often preferred over oral formulations, although it is relatively expensive and not accessible to many transgender women. Conversely, sublingual administration of estrogen tablets is widely available and could be a cost-effective alternative to transdermal estrogen. However, there are no well-conducted studies that have evaluated the safety and efficacy of sublingual estrogen therapy in the transgender population. This pilot study will elucidate how estrogen levels in the blood change following sublingual versus oral administration of estradiol in transgender women. This data may be used later to design larger studies on safety and efficacy.

Additionally, analyzing a dosage method that patients themselves have tried independently and found effective is also important. This approach incorporates intelligence from the transgender community into our research, creating new knowledge that is supported by data but is founded in existing community insights. Thus, the outcomes of this research have the potential to integrate patient input while also aiding in the development of safety recommendations, with the goal of better caring for our transgender patients.

Primary aim. To establish the pharmacokinetics of sublingual estradiol versus oral estradiol in transgender women.