McDonald CF et al. (2006) Calcitriol does not prevent bone loss in patients with asthma receiving corticosteroid therapy: a double-blind placebo-controlled trial. Osteoporos Int 17: 1546–1551

Oral glucocorticoids are associated with reduced BMD, but it is unclear whether inhaled glucocorticoids, used by most asthma sufferers, have the same effect. Calcitriol is thought to counteract the BMD loss caused by oral glucocorticoids, by promoting intestinal calcium absorption. Researchers in Australia hypothesized that inhaled glucocorticoids would also cause BMD loss that could be prevented by calcitriol treatment. They found that inhaled glucocorticoids did indeed have an adverse effect on BMD; however, this BMD loss was not prevented by calcitriol treatment.

Patients with asthma (mean age 50.6 years; 41 men and 67 women) who were taking ≥800 µg beclomethasone dipropionate (or equivalent) daily were randomly allocated to receive either 0.25 µg calcitriol twice daily, or placebo. Patients also took intermittent short courses of oral glucocorticoids. The study was completed by 41 patients in the calcitriol-treated group and 37 patients in the placebo-treated group. At 2 years, femoral-neck BMD had declined by a similar amount in calcitriol-treated patients and placebo-treated patients (1.9% versus 1.6%). Lumbar spine BMD declined in both calcitriol-treated and placebo-treated patients (by 1.6% and 0.2%, respectively); the differences between the groups were not statistically significant.

The power of the study was limited by the small sample size; however, the authors concluded that calcitriol did not prevent BMD loss and, therefore, might not be appropriate therapy for patients with asthma who take inhaled glucocorticoids.