Concomitant Administration of Low-Dose Prednisolone Protects Against In Vivo β2-Adrenoceptor Subsensitivity Induced by Regular Formoterol

To assess whether concomitant administration of low-dose prednisolone (PRED) with regular inhaled formoterol (FM) might prevent the occurrence of β2-adrenoceptor (β2-AR) tachyphylaxis. Eleven healthy male subjects (mean age, 29 years) were randomized to receive 1 week with either inhaled FM, 24 µg bid, and placebo tablets (PL), or inhaled FM, 24 μg bid, and oral PRED, 15 mg daily, in double-blind, crossover fashion, with a 2-week washout between treatments. A dose-response curve (DRC) for systemic β2-responses to inhaled salbutamol (800 to 3,200 pg) was constructed before and after each treatment period (ie, FM+PL or FM+PRED). Lymphocyte β2-AR density (Bmax) and maximal cyclic adenosine monophosphate response to isoproterenol (isoprenaline) (Emax) were evaluated ex vivo at each visit; 8 AM serum cortisol level was also evaluated as a marker of systemic glucocorticoid activity. Comparisons for DRC were made as peak responses and area under curve (AUC). There was significant (p