Therapeutic equivalence study of two formulations (innovator v. generic) of beclomethasone dipropionate in adult asthmatic patients
The original publication is available at http://www.samj.org.za
Objective. To study the therapeutic equivalence of two formulations (innovator v. generic) of beclomethasone dipropionate (BDP) 400 μg twice daily administered per metered dose inhaler (MDI), in adults with moderate to severe asthma. Methods. A double-blind randomised parallel-group trial was performed with a 2-week run-in and an 8-week treatment period. Thirty-six symptomatic adult asthmatics on a mean daily dose of 750 μg inhaled corticosteroids during run-in, a mean forced expiratory volume in 1 second (FEV1) of 70% predicted normal and a mean histamine concentration provoking a 20% reduction in FEV1 (histamine PC20) of 0.11 mg/l were randomised to one of the two treatment groups. Primary variables were morning peak expiratory flow (mPEF), FEV1 and histamine PC20. Secondary variables were β2-agonist use, symptom score and nocturnal awakening. The Schuirmann two one-sided tests procedure was used for the statistical analysis. Ninety-five per cent confidence intervals (CIs) were calculated for the differences in means. Results. The mean differences end of treatment to baseline for the two formulations (Becotide and Beclate) respectively were: mPEF 5.6 l/min (CI-16.4 - 27.6) and -22.3 l/min (CI-35.6 - -9); FEV1 -2.9% (CI -11 - 5.2) and 0.2% (CI-4.8 - 5.2); Histamine PC20 -0.04 mg/ml (CI -0.15-0.06) and 0.02 mg/ml (CI -0.37 - 0.4). Changes in clinical variables were not conclusive. The mean differences with CIs for primary variables were contained within the limits set for equivalence. The sample size was sufficient to differentiate the groups for mPEF, but this was not of clinical significance. Conclusion. After 8 weeks of treatment the two formulations of BDP, delivered by MDI through a large-volume spacer, were therapeutically equivalent in moderate-to-severe asthmatic adults.
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