Therapeutic equivalence study of two formulations (innovator v. generic) of beclomethasone dipropionate in adult asthmatic patients

Objective. To study the therapeutic equivalence of two formulations (innova tor v. generic) of bedomethasone dipropionate (BDP) 400 mug twice daily adm inistered 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 3-week treatment period. Thirty-six symptomatic adul t asthmatics on a mean daily dose of 750 mug inhaled corticosteroids during nm-in, a mean forced expiratory volume in 1 second (FEV1) of 70% predicted normal and a mean histamine concentration provoking a 20% reduction in FEV 1 (histamine PC20) Of 0.11 mg/l were randomised to one of the two treatment groups. Primary variables were morning peak expiratory now (mPEF), FEV1 an d histamine PC20. Secondary variables were beta (2)-agonist use, symptom sc ore and nocturnal awakening. The Schuirmann two one-sided tests procedure w as used for the statistical analysis. Ninety-five per cent confidence inter vals (CIs) were calculated for the differences in means. Results. The mean differences end of treatment to baseline for the two form ulations (Becotide and Beclate) respectively were: mPEF 5.61/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 d ifferences with CIs for primary variables were contained within the limits set for equivalence. The sample size was sufficient to differentiate the gr oups for mPEF, but this was not of clinical significance. Conclusion. After 8 weeks of treatment the two formulations of BDP, deliver ed by MDI through a large-volume spacer, were therapeutically equivalent in moderate-to-severe asthmatic adults.