They are held in place on the skin by an adhesive. The hormone is dissolved in the adhesive with a facilitator that allows the medication to be pushed through the skin and into the blood system. The transdermal delivery systems offer an additional benefit in that they provide a relatively smooth, constant blood level of the hormone as opposed to the rapid increases and decreases that are found with oral administration of medication. Alternative delivery systems include a transvaginal ring that releases estrogen as well as creams that also release estrogen that can be administered by the vaginal route. There are now vaginal preparations for the administration of a hormone known as progesterone.
Progesterone is a second female hormone secreted by the ovary.
Progesterone-like compounds are administered in hormone replacement therapy for women who have a uterus. Postmenopausal women with a uterus need both an estrogen and a progesterone. Hormone replacement therapy is used in order to reduce the risk of developing an endometrial cancer. Alternative routes such as transdermal or vaginal are available now and are effective as a means of delivering hormones for hormone replacement therapy in the postmenopausal individual. A woman should be advised to discuss frankly with her health care provider the use of these alternative routes for administration of hormonal medication.