New treatment strategies: ipriflavone, strontium, vitamin D metabolites and analogs.

Drugs used to treat osteoporosis can be grouped in two main categories: those that decrease bone resorption and those that increase bone formation. Antiresorptive drugs are active in preventing bone fractures in patients characterized by a negative calcium balance. However, because antiresorptive agents are often coupled to inhibition of bone formation, inhibitors of bone resorption may not be candidates as potential curative drugs in osteoporosis. Conversely, drugs that act by increasing bone formation produce an increase in bone mass above the fracture threshold; therefore, these agents are good candidates for the treatment of osteoporosis. The ideal curative drug in osteoporosis should have the ability both to decrease bone resorption and to maintain a relatively high rate of bone formation, thus inducing a favorable uncoupling of bone remodeling.