Comparison of innovator and generic salbutamol inhalers: a double-blind randomized study of efficacy and tolerance

Preliminary feedback from physicians and pharmacists in Trinidad suggests that generic pressurized metered dose inhalers (pMDIs) of salbutamol are not as effective as Ventolin and that they have poor patient acceptance. This study was designed to compare the clinical efficacy and tolerance of two generic inhalers available in Trinidad (Asthalin and Salomol) with Ventolin in stable asthmatics. Twenty-one physician-diagnosed stable asthmatics were administered the inhalers in a Latin-square randomized double-blind study with 80% power to identify differences in forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) before and 0.25, 0.5, 1, 2 and 3 h after inhalation. Pulse and blood pressure were recorded at similar time points. Seventeen patients completed the study. Within 15 min basal respiratory function significantly increased following inhalation from all three inhalers with a gradual decline over the observation period. Asthalin produced the highest changes in FEV1, PEFR and the longest duration of effect (p < 0.001). Respiratory function tests did not differ between Ventolin and Salomol. Pulse was not affected by treatments and mean arterial blood pressure fell after Asthalin. Ventolin was not superior to the generic pMDIs in improving pulmonary function. Fifteen patents reported cough sensation after Asthalin. Throat irritation and cough sensation after inhaling Asthalin may negate patient compliance. We suggest that optimizing particle size and cascade impact in the Asthalin inhaler may improve patient tolerance and acceptance with enhanced treatment outcome with cost-efficacy.