Traditional dosing strategy for asthma challenged
Doubling the dose of inhaled corticosteroids does not seem to be an effective way to prevent asthma exacerbations.
In a study published in The Lancet, Tim Harrison and colleagues from
City Hospital, Nottingham, challenge the use of this intervention when
asthma control deteriorates (2004;363:271).
They asked 390 patients deemed to be at risk of asthma exacerbations
to use an additional steroid inhaler (active or placebo) if their morning
peak flow fell by 15 per cent or if their daytime symptoms worsened.
Patients used the study inhaler for 14 days in addition to their usual
treatment and were monitored for subsequent use of oral prednisolone.
During the year-long study, the researchers found that around 12 per
cent of patients went on to need oral prednisolone whether or not they
had received increased inhaled steroid therapy.
“Doubling the dose of inhaled corticosteroid led to a small reduction
in the mean maximum fall in peak flow. There was no difference, however,
in the lowest peak flow recorded, rise
in symptom scores, or highest symptom score recorded when compared with
remaining on the same dose,” say the researchers. Furthermore,
doubling the dose of inhaled corticosteroid had no effect on the time
taken for peak flow or symptom scores to return to the baseline values.
The researchers suggest several reasons why the intervention was ineffective
at preventing exacerbations — that perhaps a doubling of the steroid
dose was an inadequate increase, or that the onset of action of inhaled
steroids may be too slow compared with the rapid deterioration in asthma
control.
Anna Murphy, consultant respiratory pharmacist, Glenfield Hospital, Leicester,
told The Journal: “We know that steroid inhalers have a flat dose-response
curve and there is little benefit for most patients in increasing the
steroid dose above 800µg of beclometasone or equivalent. Steroid
inhalers also have a slow onset of action which makes them a poor candidate
for acute management of asthma.”
She added that before the latest guidelines were published by the British
Thoracic Society and the Scottish Intercollegiate Guidelines Network
(PJ, 1 February 2003, p141) it was common practice to increase the dose
of inhaled steroids if the peak flow fell by 20–30 per cent. “In
practice, many GPs are confused by the new BTS/SIGN guidelines and are
unsure what to do for an exacerbation. I know many GPs still recommend
the doubling of the dose. Although this may be ineffective, they feel
they have treated the patient. The National Asthma Campaign is supporting
a study to look at increasing the dose by at least five times to see
if this helps.”
Ms Murphy added that recent data for Symbicort (budesonide/formoterol
fumarate) have shown that flexible dosing, when patients alter doses
themselves, reduces exacerbations, a finding that contradicts the data
from the latest study. |
The
Pharmaceutical Journal