Regulation of dosage of conjugated equine estrogen is useful for add-back therapy

In the hormonal treatment of uterine myomas, which are estrogen dependent, GnRH agonist (GnRHa) therapy has become widespread. However, the severe hypo-estrogenic state induced by the GnRHa gives rise to annoying side effects. Although the risk of these side effects may be reportedly modified when GnRHa is combined with estrogen (add-back therapy), it is difficult to target serum estradiol (E2) concentration to stay within the therapeutic window (20 approximately 50 pg/mL) by administering 0.625 mg conjugated equine estrogen (CEE)/day. Also, there is great individual variation in the circulating E2 concentration by administering the same dosage of CEE. Therefore, the use of smaller quantities of CEE in different dosages may approximate more closely to the clinical situation. This article focuses on the methods of administration of CEE combined with GnRHa for women with symptomatic uterine myomas.