Study measures effect of timed osteoporosis treatment on bone remodeling

Researchers in the Czech Republic recently tested the effect of timed osteoporosis medication injections on the daily rhythm of bone turnover among postmenopausal women.

Their results, which appear in the European Journal of Endocrinology, indicate that administration of the drug teriparatide in the morning, rather than in the evening, significantly decreased peak circadian levels of C-terminal telopeptide of type 1 collagen (beta-CTx), a marker for bone resorption.

Researchers have known for some time that bone resorption - the process by which bone minerals are broken down - operates on a circadian rhythm, peaking during the night and decreasing over the course of the day.

This rhythm does not depend on age, gender or physical activity, the study's authors said. They added that finding ways to alter the daily tempo of bone resorption and to dampen its nighttime peak may help make osteoporosis treatments more efficient.

Teriparatide is a synthetic form of parathyroid hormone, which regulates the amount of calcium in the blood and controls vitamin D synthesis in the skin. When given as a daily injection, teriparatide increases bone growth, strength and density in osteoporotic individuals of either gender, the Mayo Clinic says.

In the new study, rheumatologists and endocrinologists from Prague tested the blood levels of a number of bone resorption indicators to see how the markers responded to injections of teriparatide, which were applied either in the evening or the morning.

Researchers found that while evening shots entailed a high nighttime peak of beta-CTx followed by a low morning level, morning-time shots reduced the peak amount of beta-CTx and caused it to peak twice, at smaller levels, over the course of the day.

The team concluded that osteoclasts, the specialized cells that break down bone mineral, may be sensitive to the time of day during which osteoporosis medications are administered. In particular, the researchers theorized that choosing when teriparatide is injected may increase its efficiency.

In the U.S., an estimated 8 million women and 2 million men have osteoporosis, according to the National Osteoporosis Foundation.