Objective: To determine whether the average doses of inhaled beclomethasone, fluticasone and budesonide prescribed in primary care reflect the relative potencies of these medicines.
Methods: Retrospective analysis of 95,540 prescriptions for inhaled steroids written by 293 general practitioners in Auckland, New Zealand, between November 1995 and June 1998. In addition, 177 general practitioners were presented with two case histories describing patients with uncontrolled asthma who were not on treatment with inhaled steroids. They were asked which medicine they would prescribe and in what dose.
Results: The average daily doses prescribed were 600 microg for fluticasone, 747 microg for beclomethasone and 1184 microg for budesonide. The average dose of fluticasone was 80% of that for beclomethasone. In May 1997, when 4.5% of the prescriptions for inhaled steroids were for fluticasone, the average doses of fluticasone and beclomethasone were 632 microg and 760 microg, respectively. By May 1998, when 23% of prescriptions were for fluticasone, the average doses of fluticasone and beclomethasone were little changed at 610 microg and 726 microg, respectively. In response to the two case histories, the average doses of fluticasone chosen were 71% and 77% of the doses of beclomethasone.
Conclusions: The average prescribed dose of fluticasone was 80% of that for beclomethasone, even though fluticasone is at least twice as potent as beclomethasone. Similar findings were observed when the general practitioners responded to the case histories. The high doses of fluticasone prescribed may be due to a failure to appreciate that fluticasone is twice as potent as beclomethasone and to the availability of high strength preparations of fluticasone, i.e. 250 microg per actuation.