Differences in the potencies of inhaled steroids are not reflected in the doses prescribed in primary care in New Zealand

Objective: To determine whether the average doses of inhaled beclomethasone , fluticasone and budesonide prescribed in primary care reflect the relativ e potencies of these medicines. Methods: Retrospective analysis of 95,540 prescriptions for inhaled steroid s written by 293 general practitioners in Auckland, New Zealand, between No vember 1995 and June 1998. In addition, 177 general practitioners were pres ented with two case histories describing patients with uncontrolled asthma who were not on treatment with inhaled steroids. They were asked which medi cine they would prescribe and in what dose. Results: The average daily doses prescribed were 600 mu g for fluticasone, 747 mu g for beclomethasone and 1184 mu g for budesonide. The average dose of fluticasone was 80% of that for beclomethasone. In May 1997, when 4.5% o f the prescriptions for inhaled steroids were for fluticasone, the average doses of fluticasone and beclomethasone were 632 mu g and 760 mu g, respect ively. By May 1998, when 23% of prescriptions were for fluticasone, the ave rage doses of fluticasone and beclomethasone were little changed at 610 mu g and 726 mu g, respectively. In response to the two case histories, the av erage doses of fluticasone chosen were 71% and 77% of the doses of beclomet hasone. Conclusions: The average prescribed dose of fluticasone was 80% of that for beclomethasone, even though fluticasone is at least twice as potent as bec lomethasone. Similar findings were observed when the general practitioners responded to the case histories. The high doses of fluticasone prescribed m ay be due to a failure to appreciate that fluticasone is twice as potent as beclomethasone and to the availability of high strength preparations of fl uticasone, i.e. 250 mu g per actuation.