Men's Osteoporosis Support Group

Taking other osteoporosis medications before Forteo

J Clin Endocrinol Metab. 2007 Dec 26 [Epub ahead of print], Effects of Prior Antiresorptive Therapy on the Bone Mineral Density Response to Two Years of Teriparatide Treatment in Postmenopausal Women with Osteoporosis. Boonen S and others. PMID: 18160462. This study was designed to see if there were any significant effects on bone mineral density (BMD) of the spine or hip if women had taken another osteoporosis medication before starting teriparatide (Forteo). A previous Update cited two studies that found it was not beneficial to take Forteo along with Fosamax. However, the Boonen and others study was designed to test the effect of prior bisphosphonates, or other approved osteoporosis medications, that were stopped before starting two years of teriparatide therapy.

This is a complex 27-page study that the abstract summarizes quite well with the conclusion that, "Teriparatide induces positive effects on BMD and markers of bone formation in postmenopausal women with established osteoporosis, regardless of prior long-term exposure to antiresorptive therapies." Basically the only observable effects from the previous long-term antiresorptive therapies was a transient decrease in total hip BMD at six months. At the 18- or 24-month check this was corrected with increased BMD in all groups of patients, no matter what antiresorptive therapy they had taken. Another interesting finding was that biochemical markers of bone formation were increased in all groups when checked after one month of teriparatide. Remember that teriparatide is a form of human parathyroid hormone that increases bone formation via stimulating osteoblasts. So, if teriparatide is stimulating bone formation as expected, we would expect biochemical markers of bone formation to be elevated upon testing. This is opposed to the method of action of the bisphosphonates, such as Fosamax (alendronate) or Actonel (risedronate), which stop the breakdown of bone by their effect on the osteoclasts. Thus we test for their effect by checking biochemical markers of bone breakdown, which should be lower than before therapy commenced.

There was an incidence of hypercalcemia in about 6% of the patients, which is in line with other studies that used teriparatide. So serum calcium levels are tested routinely whenever taking teriparatide.

Editor's comments: These findings are important because patients won't always be starting osteoporosis therapy with teriparatide. Often they may start with another approved osteoporosis medication but find they are not getting the desired results. The Boonen and others study shows that results with teriparatide should be adequate even if patients had been on long-term therapy with another medication before switching to teriparatide. Note that teriparatide is only given for a maximum of 24 months and then must be followed by some other osteoporosis medication for the duration. Another Update cites a study which showed that the gains in BMD were not maintained after stopping teriparatide except for those patients who followed up with Fosamax. Even though the Boonen and others study only included women, equal results should be expected with men since gender is not an issue with teriparatide's method of action, and it has been approved for use in men and women.

Return to Home