Combination therapy with anabolic and antiresorptive agents

Combination therapy, the use of an anabolic agent with an antiresorptive agent in some sequence, has been evaluated in a number of clinical trials. There is no fracture data on combination therapy except for a small trial using PTH and estrogen. It appears that simultaneous use of a bisphosphonate (alendronate 10 mg per day) with PTH offers no advantage (and appears to blunt PTH's effect) compared with the use of PTH alone based on bone density gains. Previous therapy with alendronate also blunts gains in bone density with PTH therapy. Estrogen and raloxifene, whether given before or with PTH, do not blunt its anabolic effect. Sequential therapy with PTH followed by an antiresorptive agent (alendronate) offers the greatest gains in bone mass. It is possible that alendronate or other bisphosphonates given in a different dosing regimes may have different effects on PTH's anabolic effect. More trial data on combination therapy is needed.