They suggest that the modified estrogen could be particularly helpful in treating vaginal atrophy in women for whom estrogen replacement is not advised, including those with breast or endometrial cancer. The drug has not yet been tested in humans. If the new estrogen ultimately proves to restore some of the physical comfort of sexual intercourse in postmenopausal women while reducing health risks, it could provide an important new tool in the treatment of female sexual dysfunction in much the same way that Viagra has helped relieve impotence in some men, predicts Hochberg. Studies have shown that more than 40 percent of postmenopausal women experience the condition, which causes thinning of the vaginal wall, dryness and itching, and leads to painful intercourse and sometimes bleeding. In addition to oral estrogen replacement therapy, vaginal atrophy can be treated with various lubricants, but these offer only temporary relief of symptoms and do not strengthen the vaginal wall, as estrogen does.
Vaginal creams containing estrogens are available and can alleviate symptoms.
But such estrogen-based products are easily absorbed into the bloodstream and transported throughout the body, elevating health risks similarly to oral estrogen therapy, according to the researchers. To reduce the risks, Hochberg and his associates created a modified version of estradiol, which is the major human estrogen. The new formulation stimulates vaginal cells but afterward is rapidly destroyed by the body's enzymes, which prevent it from circulating to other tissues and organs. In tests with rats, the estrogen showed no systemic action when injected under the skin. The researchers are collaborating with scientists at Columbia-Presbyterian Hospital in New York City to determine whether the drug causes vaginal stimulation or systemic action in female rhesus monkeys that do not produce estrogen.