Alternatives to Estrogen for Osteoporosis: SERMs in Development

For years, estrogen therapy was a principal method used to treat ailments associated with menopause, such as osteoporosis. However, when the potential for serious negative health consequences - including increased risk of breast cancer and heart attacks - was discovered, the use of estrogen for this purpose was drastically curtailed.

In the five to seven years after menopause, a woman may lose up to 20 percent of her bone mass without treatment. In recent years a number of doctors have turned to other drugs known as SERMs, or selective estrogen receptor modulators, to combat this problem, which can otherwise leave a woman at serious risk of fracture.

Evista for Osteoporosis and Benefits of SERMs

The advantage of SERMs is that their effects resemble those of estrogen on some parts of the body, significantly the bones, while not acting as estrogen on other areas, such as the breasts. One medicine, raloxifene, currently sold as Evista by Eli Lilly, is approved by the FDA for the prevention and treatment of osteoporosis in postmenopausal women.

Drug in Development, Viviant (Bazedoxifene), May Be Comparable to Evista

But other pharmaceutical companies are conducting research to provide women additional options. Among the most promising options is bazedoxifene, a drug being developed by Wyeth to be sold as Viviant. Thus far Vivant has received two approvable letters from the FDA for use in osteoporosis prevention, and action from the agency is expected in the near future regarding its use in osteoporosis treatment. In studies thus far, its bone-building effects have appeared comparable to those of raloxifene / Evista.

Bazedoxifene Also Being Tested As Part of Aprela

In addition, bazedoxifene is also under study for use in another drug, Aprela. In this formulation the medication would be brought together with conjugated estrogens (derived from the urine of pregnant mares), currently sold as Premarin. This combination would have the prospect of providing additional benefits to women - such as curbing hot flashes - associated with hormone therapy, but with fewer risks.

A "Next Generation" Hormone Therapy Drug

"Aprela is a next generation hormone therapy," says Wyeth spokesperson Danielle Halstron of the potential bazedoxifene/conjugated estrogens formulation. "When you bring those two things together, you have a hormone therapy that has been shown to be safe on the breasts and safe on the uterus."

Wyeth hopes to submit Aprela to the FDA by the middle of 2008.

Another Possible Option, Another SERM

At the same time Pfizer is working on a different SERM for osteoporosis treatment known as lasofoxifene, which it submitted to the FDA earlier this year. The drug, which now uses brand name Fablyn, has previously encountered setbacks in its road to the marketplace In 2005 it received a non-approvable letter from the FDA as Oporia, its previous brand name.