The Effects of Inhaled Glucocorticoids on the Postmenopausal Skeleton

Overview

There are over 10 million individuals with asthma using inhaled glucocorticoids (IGCs) in the United States. While oral GCs are recognized to have destructive skeletal effects, far less is known about the effects of IGCs. This gap in our knowledge is of critical importance, not only because of the prevalence, chronic nature and long duration of IGC use, but also because several studies have found that patients using IGCs are at increased risk of fracture. Fracture risk is greatest in postmenopausal (PM) women, in whom IGCs may augment negative effects of estrogen loss and aging. The investigators hypothesize that initiation of IGCs in IGC naïve PM women will lead to decreased bone formation and uncoupling of bone turnover, a potential mechanism for the effect of IGCs on the skeleton. To test our hypothesis, the investigators will perform a randomized, controlled 4 week study of the acute effects of commonly used doses of budesonide (360 or 720 mcg) on bone turnover and circulating osteoblast precursors in 60 treatment naïve, non-asthmatic, PM women. These studies are of high clinical significance because there are currently no guidelines regarding screening, prevention or treatment for osteoporosis in patients using IGCs, nor is IGC use taken into account when calculating fracture risk in PM women, the group at highest risk of fracture. High quality evidence for low volumetric bone mineral density (BMD) and abnormal bone quality in PM women using IGCs has the potential to change clinical practice by supporting specific interventions to prevent bone loss and fractures.

The investigators will study acute biochemical and hormonal responses over 4 weeks to commonly prescribed moderate and high doses of budesonide one of the most widely prescribed IGCs, and the preferred drug for Medicare and Medicaid. Sixty treatment naïve PM non-asthmatic women will be randomized to one of 3 groups (20/group): placebo, budesonide 360 or 720 mcg/day. IGCs will be self-administered as 2 puffs twice daily. Budesonide will be provided as Pulmicort flexhaler. At the baseline visit, subjects will be taught proper technique for self-administration of the inhaled medications, including mouth rinsing after each dose. Since dry powder formulations will be used, spacer devices are not required. Women will be assessed at baseline, 1,2, and 4 weeks. This time period and schedule was chosen to ensure adequate time for IGCs to reach peak levels, and to assess the bone metabolic response. Given the 4-6 hr half-life of budesonide, steady state pharmacokinetics will be reached at one week. The investigators will monitor medication adherence using the inhaler's device counter. Visits will be conducted in the Metabolic Bone Diseases Unit. To measure systemic absorption, serum steroid levels will be directly measured.To assess the effects of IGC and dose on the hypothalamic-pituitary-adrenal (HPA) axis, morning (AM) cortisol will be measured at each visit and urinary free cortisol at baseline and 4 weeks.