The assessment of the systemic effects of inhaled glucocorticosteroids. The effects of inhaled budesonide vs oral prednisolone on calcium metabolism.

In a randomized, double-blind crossover study, the effects of 0.8, 1.6 and 3.2 mg/day inhaled budesonide and 5, 10 and 20 mg/day oral prednisolone on mineral metabolism were compared. Twelve healthy subjects (4 m, 8 f) were treated for 1 week at each dosage level, the graduated dosages being given in ascending order. Budesonide and prednisolone were given twice daily and once daily, respectively, which reflects the schedules common in clinical practice. Serum calcium and the regulatory hormones of calcium metabolism (parathyroid hormone, vitamin D metabolites and calcitonin) were not changed either by prednisolone or budesonide. Prednisolone significantly increased 24 h and 08.00 h fasting urinary calcium excretion and decreased renal calcium reabsorption, while budesonide had little or no effect on urinary calcium loss and increased renal reabsorption at the highest dose level. Both drugs significantly increased renal phosphate reabsorption and serum phosphate levels, but prednisolone caused greater increases than budesonide. In conclusion, during short-term treatment with the dosages used, inhaled budesonide had less effect on calcium and phosphate metabolism than oral prednisolone, and so it may have a lesser action on the skeleton of the type contributing to osteoporosis during long-term treatment.