NEW YORK (Reuters Health) – The risk of hip fracture is significantly lower when organic nitrates are used as needed rather than continuously, according to a February 3rd online report in the Journal of Clinical Endocrinology and Metabolism.

The drugs – nitroglycerin and isosorbide dinitrate or mononitrate – are reportedly associated with increased bone mineral density and a decreased risk of fracture, according to lead author Dr. Sander Pouwels, of Utrecht University, the Netherlands, and colleagues.

In order to analyze these associations more closely, the authors performed a population-based a case-control study using data from the Dutch PHARMO Record Linkage System from 1991 to 2002.

The 6763 cases (patients with a first hospital admission for hip fracture) were compared to 26,341 controls, who were “enrolled” in the study on dates that matched the fracture dates of the cases.

Among current nitrate users, there was no difference between cases and controls in hip fracture risk (adjusted odds ratio = 0.93). Hip fracture risk was lower among those who used as-needed nitrates compared to those who used maintenance medication (adjusted ORs = 0.83 and 1.17, respectively).

There was no association of hip fracture risk with duration of nitrate use nor with discontinuation of nitrates.

There are several theories as to why intermittent exposure to nitrates may have a beneficial effect on fractures. “It has been hypothesized that tachyphylaxis, i.e., the development of nitrate tolerance, could affect the potential beneficial effects of organic nitrates on BMD,” the authors explain.

Another possibility is that maintenance medication users may have an increased risk of orthostatic hypotension, “which can result in falling and ultimately in a hip fracture,” the researchers note.

Reference:

J Clin Endocrinol Metab 2010.