Researchers testing the effects of two bone active drugs in heart transplant recipients have found that both reduce the degree of bone loss commonly seen in the first year following transplant surgery. The drug alendronate, however, which reduces the activity of cells that cause bone loss, was judged to be more clinically useful than calcitriol, a synthetic substance similar to vitamin D, which helps regulate calcium metabolism in the body. The results point to the value of treating bone loss in transplant patients.

The study, published February 19 in the New England Journal of Medicine, was funded in part by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), one of the Department of Health and Human Services' National Institutes of Health.

Elizabeth Shane, M.D., of the Columbia University College of Physicians and Surgeons in New York, and her colleagues there and at the Newark-Beth Israel Medical Center in New Jersey conducted a randomized trial involving 149 patients in whom either alendronate or calcitriol was begun within the first few weeks after heart transplantation. The results were compared with those from a reference group of 27 patients who had undergone transplantation during the same time period. No significant difference in either bone loss or fracture rate was found between the two treatment groups, and both drug groups showed reduced bone loss compared to the reference group. Alendronate, say the scientists, might be easier to monitor in these fragile patients, as calcitriol caused higher calcium levels in the blood and urine.

"The bottom line," says Joan McGowan, Ph.D., chief of the NIAMS Musculoskeletal Diseases Branch, "is that drugs to prevent bone loss should be considered in all transplant patients."

Transplant recipients are at high risk for osteoporosis, a skeletal disorder marked by reduced bone strength and fractures, because of the drugs they must take to prevent the body's rejection of the transplanted organ. The fracture rate is particularly high for heart transplant patients.

The trial was difficult to conduct and monitor because of the serious medical conditions involved and the lack of control over the many drugs and interventions related to the transplantation.

"I think the trial provides good insight for clinicians," says Dr. McGowan. "It is hoped that this will bring more attention to post-transplant bone loss and its prevention."

Additional funding for the study was provided by the National Center for Research Resources, also a part of the National Institutes of Health, and Merck.

The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases, the training of basic and clinical scientists to carry out this research, and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at www.niams.nih.gov. Information on osteoporosis is available from the NIH Osteoporosis and Related Bone Diseases~National Resource Center; phone toll-free 800-624-BONE (2663), or visit www.osteo.org.

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Shane E, et al. Alendronate versus calcitriol for the prevention of bone loss after cardiac transplantation. NEJM 2004;350(8):767-776.