The Effect of Efavirenz on Estradiol Metabolism in Transgender Women

The goal of hormonal therapy in treating gender dysphoria is to maintain cross-sex hormone levels in the normal physiological range for the desired gender. Estrogen is the mainstay of hormonal therapy for male to female transgender patients. Efavirenz, a non-nucleoside reverse-transcriptase inhibitor, has been one of the most commonly prescribed antiretroviral therapies (ARTs). However, this regimen has also given rise to the most clinically significant drug–drug interactions between ARTs and hormone-based contraceptives. We discuss here three transgender HIV-positive women in whom efavirenz effected the metabolism of orally administered estradiol (and probably medroxyprogesterone).