Objectives: Novel assays have been developed for markers of type 1 collagen turnover. The aim of this study was to evaluate the effect of short-term exposure to inhaled corticosteroids on both the novel and conventional markers of bone metabolism.
Methods: Nine healthy subjects received 2 weeks treatment with inhaled budesonide 800 micrograms per day in week 1, and 1600 micrograms per day in week 2, or fluticasone 750 micrograms per day in week 1 and 1500 micrograms per day in week 2, with a 1-week washout in between. Measurement of carboxy-terminal propeptide of type 1 collagen (PICP), carboxy-terminal telopeptide of type 1 collagen (ICTP), plasma alkaline phosphatase bone isoenzyme, and 24-h urinary calcium excretion were made at baseline and at the end of each 2-week treatment period.
Results: ICTP was significantly reduced following treatment with budesonide but not fluticasone compared with baseline: baseline 4.2 micrograms.l-1 budesonide 3.0 micrograms.l-1, fluticasone 3.6 micrograms.l-1. There were no significant changes in PICP compared with baseline after treatment with budesonide or fluticasone. The ratio of PICP:ICTP increased significantly after treatment with both budesonide and fluticasone compared with baseline: baseline 27.4, budesonide 43.7, t 42.6. There were no significant differences between the two treatments for any of the measured parameters.
Conclusions: Thus, when using sensitive markers of collagen turnover, short-term inhaled corticosteroid therapy was found paradoxically to reduced bone resorption.