According to a study published early online in the Annals of Emergency Medicine, two days of dexamethasone is as effective as five days of prednisone for the treatment of adults with asthma flares.

The authors note that many clinicians use a brief course of prednisone for the treatment of mild to moderate asthma.  As the bioavailability of dexamethasone is equivalent to prednisone but it has a longer half-life (up to 72 hours), it may offer a shorter, alternative treatment option to possibly improve compliance. 

This study involved adults presenting to the emergency department (ED) with an acute asthma exacerbation (peak expiratory flow [PEF] <80% of ideal).  They were randomised to receive double-blind treatment with either oral dexamethasone (16mg daily for two days) or oral prednisolone (50mg daily for 5 days).  Patients were contacted by telephone two weeks after their visit and asked about the length of time until return to normal daily activities, the number of times salbutamol was used per day in the week following the visit, and whether they suffered a relapse (defined as repeat hospital admission or visit to their primary care provider within the 2-week follow-up period). 

Although 257 patients were initially randomised and included in the study, 57 of these were lost to follow-up (25 in the dexamethasone group and 32 in the prednisone group).  In total 96 patients randomised to prednisone and 104 to dexamethasone completed the study regimen and follow-up and were included in the analysis. The main findings were as follows:

• 90% of patients in the dexamethasone group and 80% of those in the prednisone group reported a return to normal activities within three days (difference 10%; 95% CI 0% to 20%; P=0.049).

• The rate of relapse was similar between groups (13% versus 11%; difference 2%; 95% CI –7% to 11%, P=0.67).

The authors highlight the limitations of their study: the use of number of days until patients believed they were able to return to their normal activities as the primary outcome measure (rather than an asthma scoring system), and the large loss to follow-up (it is unknown whether outcomes might have differed between those who were and were not contactable). 

The authors conclude that their results suggest a 2-day course of oral dexamethasone is at minimum as effective as a 5-day course of oral prednisone in the treatment of mild to moderate asthma exacerbations in patients who are discharged from the ED.  They comment that the study “contributes to the growing body of evidence that equivalent potencies of different corticosteroid preparations are at least equally effective in the treatment of acute asthma exacerbation and that the convenient short-course dosing of dexamethasone makes it an attractive treatment option.”