The combination of two different drugs for osteoporosis was found to increase bone mineral density (BMD) more than treatment with either drug alone, according to the results of a small clinical trial published in The Lancet.

The combination, which included teriparatide, a bone-building (anabolic) drug, and denosumab, a targeted therapy to stop bone loss, also increased BMD better than previously reported with any available treatment in postmenopausal women with osteoporosis.

According to Medilexicon’s medical dictionary, osteoporosis is a “reduction in the quantity of bone or atrophy of skeletal tissue; an age-related disorder characterized by decreased bone mass and loss of normal skeletal microarchitecture, leading to increased susceptibility to fractures.

Early signs of osteoporosis include joint pains, difficulty standing, and difficulty sitting up straight. As the patient’s bone density or bone mass keeps going down, fractures of the wrist, hip, or bones in the spine become more common.

Most currently available treatments for osteoporosis include drugs like denosumab, which are antiresorptive – they block the action of cells that break down bone (osteoclasts) during the normal process of bone remodeling in order to curb bone loss.

The drug teriparatide, on the other hand, has a different mechanism of action. It works by increasing the activity of osteoblasts in order to stimulate the development of new bone.

Until now, scientists have not been able to successfully combine these methods.

In the novel research, investigators from Massachusetts General Hospital in Boston randomly assigned 94 postmenopausal women with osteoporosis to receive either teriparatide (20 micrograms daily), denosumab (60 mg every 6 months), or both medications for 1 year.

The experts used low-dose x-rays (dual energy x-ray absorptiometry, or DXA) and bone biomarkers to measure changes in lumbar spine, hip bone, and femoral neck at the start of the study and at 3, 6, and 1 year.

According to the results, the combination therapy improved BMD at the spine, hip, and femoral neck significantly better than either drug by itself.

“One year improvements in femoral neck (4.2%) and hip (4.9%) BMD in the combined group were greater than previously reported for any approved treatment,” the researchers said.

Bone formation was also reduced less in females receiving combination therapy compared to those given only denosumab.

Lead author Benjamin Leder said:

“Our results demonstrate that the combination of denosumab and teriparatide increases bone density more than either individual therapy, most likely because denosumab is able to potently block bone resorption (loss) even when given along with a bone-building agent like teriparatide. While additional studies are needed, the results suggest that this combination may prove to be an effective osteoporosis treatment in women at especially high risk of fracture.”

In a linked Comment, Richard Eastell, Director of the Mellanby Centre for Bone Research, and Jennifer Walsh, from the University of Sheffield in the UK, wrote:

“Whether the combination remains effective needs to be investigated, however, because at 12 months mean concentrations of the bone formation marker PINP no longer differed between the denosumab-alone and combination-therapy groups.

The safety of this combination therapy also needs to be explored, as does what happens when teriparatide is stopped (the licence only supports use for a maximum of 24 months). Finally, the reduction in fracture risk needs to be quantified so that cost-effectiveness can be assessed.”

A previous study showed that women who suffer from depression are more likely to reach the menopause with an increased risk of osteoporosis.

Written by Sarah Glynn