Raloxifene and PTH may have synergistic effect on BMD.(Gynecology)

SAN ANTONIO -- Women who are taking raloxifene for osteoporosis do not need to stop taking the bisphosphonate to begin parathyroid hormone therapy.

In fact, the two drugs may have some synergy, Chad Deal, M.D., said at the annual meeting of the American College of Rheumatology.

In a 6-month study comparing parathyroid hormone (1-34) plus raloxifene with parathyroid hormone monotherapy, the combination increased total hip bone density to a greater degree, observed Dr. Deal, who is the head of the center for osteoporosis and metabolic bone disease at the Cleveland Clinic Foundation.

The combination "could potentially enlarge the anabolic window, maximizing the formation of bone and minimizing the resorption of bone," said Dr. Deal, whose study included measurements of bone turnover markers.

Dr. Deal's double-blind study enrolled 137 subjects who were randomized to daily therapy with either the combination of teriparatide (Forteo), 20 mcg, plus raloxifene (Evista), 60 mg, or to monotherapy with teriparatide, 20 mcg.

All of the study participants also received calcium and vitamin D supplementation.

At 6 months' follow-up, the combination increased bone mineral density over baseline by a mean 6.19% at the lumbar spine, a mean 2.23% at the femoral neck, and a mean 2.31% for the total hip, as measured by dual x-ray absorptiometry. By comparison, teriparatide increased lumbar spine density by a mean 5.19%, femoral neck density by a mean 1.03%, and total hip density by 0.68%.