Mycophenolate mofetil : A promising new immunosuppressant that does not cause bone loss in the rat

Background. Posttransplantation bone disease is a well-described phenomenon; among its etiology is immunosuppressant-induced bone disease. Mycophenolate mofetil (MMF) has emerged as a promising new immunosuppressant. Our study was designed to investigate the effect of MMF on in vivo bone mineral metabolism. Methods. Twenty-four 6-month-old male Sprague-Dawley rats were randomized into two groups to receive either MMF vehicle daily for 28 days or 30 mg/kg MMF daily for 28 days. The serum was assayed for osteocalcin and 1,25-dihydroxy vitamin D 3 . Subsequent to double-labeling, the right tibiae were removed on day 28 for histomorphometry. Results. MMF suppressed bone gla protein (osteocalcin) levels on days 14 and 28 (P<0.05). Except for percentage osteoid perimeter, there was no difference in bone histomorphometry between the two groups. Conclusion. In this relatively short-term study, MMF did not cause osteopenia in the rat model, but the suppressed bone gla protein merits further study.