Estradiol undecylate (EU or E2U), also known as estradiol undecanoate and formerly sold under the brand names Delestrec and Progynon Depot 100 among others, is an estrogen medication which has been used in the treatment of prostate cancer in men.It has also been used as a part of hormone therapy for transgender women. Although estradiol undecylate has been used in the past, it was discontinued and hence is no longer available.The medication has been given by injection into muscle usually once a month.
Side effects of estradiol undecylate in men may include breast tenderness, breast development, feminization, sexual dysfunction, infertility, fluid retention, and cardiovascular issues.Estradiol undecylate is an estrogen and hence is an agonist of the estrogen receptor, the biological target of estrogens like estradiol.It is an estrogen ester and a very long-lasting prodrug of estradiol in the body.Because of this, it is considered to be a natural and bioidentical form of estrogen.An injection of estradiol undecylate has a duration of about 1 к 4 months.
