Potency ratio fluticasone propionate (Flixotide Diskus)/budesonide (Pulmicort Turbuhaler)

In the choice of, or switch between, various inhaled corticosteroids (ICS) it is important to know equipotent doses for clinical treatment effects of the alternatives. Various ICS do have different inherent potency. Further, the ICS are delivered from inhalers that may differ markedly in output characteristics and drug delivery to intrapulmonary airways. Therefore, clinical efficacy comparisons must include drug-inhaler comparisons. We estimated the therapeutic potency ratio of the Flixotide Diskus (fluticasone propionate, FP) and the Pulmicort Turbuhaler (budesonide, BUD) in steroid-naive asthma patients, using a dose-reduction technique (FP 500-0 mcg/day, BUD 800-0 mcg/day). The dose defining end point was loss of asthma control in this paper denoted as exacerbation. In total, 282 patients with proven asthma were enrolled in the study, and 103 in the FP group and 98 in the BUD group completed the study per protocol. In total, 80 patients in the FP-group and 79 in the BUD-group experienced a dose defining exacerbation. The exacerbation frequency increased in a dose-dependent way as the dose was titrated down. From these data the potency difference between the present drug inhaler combinations, Flixotide Diskus and Pulmicort Turbuhaler, was calculated to be between 1.50:1 (95% CI 1.10:1-2.05:1) and 1.75:1 (CI 1.26:1-2.43:1) depending on if patients with insufficient steroid-response were excluded from the calculations or not. In these steroid-naïve patients, the potency difference was evident only at low daily doses, below 200 mcg.