Despite the established efficacy of inhaled corticosteroids in improving lu
ng function in asthma, there has not been a corresponding improvement in mo
rbidity and mortality associated with the disease, which, in part, may resu
lt from noncompliance with the prescribed regimen. The reasons for this are
many and varied, but an important measure in improving the level of compli
ance in asthma patients is simplification of the treatment regimen, which m
ay be achieved by reducing the dose frequency and improving the ease of adm
inistration. In clinical trials designed to determine whether a reduction i
n dose frequency to once daily is associated with similar efficacy to that
with more frequent administration, a number of studies have shown that once
-daily administration of inhaled corticosteroids in both adults and childre
n is as effective in controlling asthma as twice-daily administration of th
e same dosage, both when given as initial therapy in corticosteroid-naive p
atients and in patients already receiving an inhaled corticosteroid. The dr
ug for which most evidence to support a dosage change from twice-daily to o
nce-daily therapy currently exists is budesonide, though limited evidence w
ith other inhaled corticosteroids such as beclomethasone dipropionate, flut
icasone propionate and flunisolide also supports once-daily use. Despite th
e larger single dosage with once-daily budesonide therapy, there has been n
o evidence in clinical trials of a greater incidence of local adverse effec
ts such as hoarseness, throat irritation or oropharyngeal candidosis, and n
o evidence of adrenal suppression or growth retardation.
Since compliance is an important factor that can affect the success or fail
ure of asthma therapy, a reduction in the frequency of administration to on
ce daily offers the potential advantage of improved compliance with treatme
nt and hence better control of asthma. In the short term clinical trials co
nducted to date, patient preferences have favoured the once-daily regimen o
ver twice-daily administration. When combined with other (e.g. educational)
measures to improve patient compliance, a switch from twice-daily (or more
frequent) administration to once-daily inhaled corticosteroid therapy seem
s likely to be beneficial in improving the long term outcome of treatment.