We read with interest the letter signed by Doctors Entrenas-Costa and Entrenas-Castillo1 in which they suggest that the classification of the dose of 100μg of fluticasone furoate (FF) once a day (OD) that appears in the GEMA guidelines as medium dose2 should be “corrected” and classified in line with the GINA guidelines as low dose.1

GEMA is a clinical practice guideline drawn up by independent experts from 15 different scientific societies.2 The classification of 100μg FF OD as a medium dose is evidence-based and consistent with the approved Summary of Product Characteristics (SPC) for FF3 and with the classifications of other relevant international guidelines, such as SIGN 158 in the UK and the Australian Asthma Handbook. Few direct comparisons are available with FF and other inhaled glucocorticoids, particularly at low doses, so it is difficult to establish the exact equipotent dose (equivalent in efficacy and safety) of FF. According to the SPC, a daily dose of 100μg of FF in asthma is approximately equivalent to 250μg of fluticasone propionate (FP) twice a day (BID, medium dose), while 200μg FF OD is approximately equivalent to 500μg FP BID (high dose).3 A low dose of FF is not approved in asthma. Evidence of efficacy and safety with 50μg of FF OD in mild-moderate asthma is low and inconsistent, although at least one of the published studies indicates greater efficacy than placebo and approximately similar efficacy to that of low-dose FP (100μg BID) in mild asthma.4

With regard to safety, the authors comment that the dose of 100μg FF does not suppress cortisol, based on a pharmacokinetic/pharmacodynamic model and limited data from a 6-week study.1 However, in a 52-week study of 503 adults and adolescents with asthma specifically designed to assess safety, 24-h urinary cortisol excretion at the medium dose of 100μg FF OD was similar to that obtained at the high dose of 500μg FP BID after 1 year of treatment, and about 10% of patients treated with 100μg FF had persistently low urinary cortisol levels (<40nmol/24h) during treatment.5 All inhaled glucocorticoids present a risk of systemic (e.g. pneumonia, cortico-adrenal axis suppression, osteoporosis, glaucoma, etc.) and local (candidiasis, etc.) adverse effects, all of which are dose-dependent.

As a result, until new data become available, we believe that the classification of 100μg FF as a medium dose is the most correct and prudent option. Treatment for asthma maintenance should be administered at the minimum dose required to maintain disease control2 in order to minimize the risk of adverse effects.