New and exciting research initiatives have yielded several promising osteoporosis prevention and treatment options. Recent research also reaffirms the benefits of currently available treatments and suggests better results with improved application of existing therapies;
Of the emerging therapies under investigation, diphosphonates and nasal calcitonin show the greatest promise for safe and effective osteoporosis management. Research continues to evaluate the role of growth factors or growth hormones and sodium fluoride in osteoporosis.
Diphosphonates are chemical compounds that bind to bone tissue and can impede bone resorption or removal, either by direct or indirect effect on osteoclasts (bone-resorbing cells). Several completed and ongoing studies suggest that diphosphonates can effectively treat osteoporosis by inhibiting bone resorption and assisting bone formation, resulting in a small increase in bone mass and a reduction of the symptoms of osteoporosis.
A diphosphonate being studied in a multicenter trial seems to be most effective when given in a cyclical-type therapy, a therapeutic practice in which the drug is administered for about 2 weeks to inhibit bone resorption by osteoclasts, and subsequently discontinued for 10 weeks, during which time a calcium supplement is given and osteoblasts form new bone as a normal part of the skeletal remodeling process.
Studies thus far have shown that diphosphonate therapy is associated only with occasional, mild gastrointestinal side effects. Diphosphonates hold added promise because their usage in cyclical therapy is relatively inexpensive.
Nasal salmon-calcitonin, a synthetic formulation of a naturally occurring hormone secreted by the thyroid gland, is currently undergoing clinical trials that indicate that it prevents progressive bone loss, primarily by inhibiting the action of osteoclasts, or bone-resorbing cells. The drug may have the added benefit of improving mobility and easing the pain associated with osteoporosis.
In two double-blind, placebo-controlled trials, 37 women with established postmenopausal osteoporosis, and 39 early postmenopausal women, were given either nasal calcitonin and calcium or placebo and calcium. Study results show that nasal calcitonin may delay bone loss in women with established osteoporosis, and it may prevent spinal bone loss in early postomenopausal women.
An injectable form of salmon-calcitonin is associated with occasional, mild side effects, such as nausea. Although calcitonin's efficacy has been studied for 2 to 3 years, longer-term studies have not been completed.
Growth factors and growth hormones stimulate the products of bone by osteoblasts. Insulin-like growth factor 1 (IGF-I) is the most promising of many growth factors that take part in the process of bone remodeling. Growth hormone, synthesized with recombinant technology to stimulate a hormone secreted by the pituitary gland, acts on naturally occurring IGF-I to stimulate bone production.
Although there are many potential benefits of growth factor and growth hormone therapy, they will probably not be available in the near future. Research is currently underway to develop appropriate drug delivery systems and determine dosage requirements. Also under investigation is the use of growth factors and growth hormones in cyclical therapy, which many researchers feel will optimize therapeutic efficacy.
Sodium fluoride is a chemical compound that increases bone mass by stimulating osteoblasts, or bone producing cells, particularly in the trabecular or sponge-like bone found in the spine.
Some studies have shown that fluoride may lessen the risk of vertebral fractures, the most common type of fractures associated with osteoporosis, which lead to curvature of the spine. Other studies indicate, however, that sodium fluoride may actually increase the risk of hip fractures, and there are several side effects associated with the use of sodium fluoride that require further research.
Available evidence has not confirmed sodium fluoride's efficacy in long-term therapy, and the drug's side effects, including gastrointestinal distress and lower extremity pain, can affect up toy 50% of patients.
Estrogen replacement therapy, or ERT, the most commonly used preventive therapy in osteoporosis, inhibits the acceleration of bone loss that occurs after menopause and has been shown to reduce the frequency of fractures. Nearly 2 decades 4 of clinical experience with ERT provides accurate guidelines for achieving optimal benefits.
ERT should be continued for at least 5 years. In those with an intact uterus, a progestogen should be added to reduce the risk of endometrial cancer. Longterm ERT reduces fractures at all skeletal sites, reducing the risk of hip fractures by around 50%.
Calcium and other nutrients, particularly vitamin D, play an important role in healthy bone production. Long-term nutritional deficiency of calcium probably results in a permanent skeletal deficit, increasing the risk of osteoporosis and fractures. The importance of calcium intake increases with age, particularly for postmenopausal women, and warrants calcium supplementation when recommended intake levels are not achieved through diet.
For more information, contact Michael Segger or Michael Rinaldo, 212-265-9150.