Comparative lung delivery of salbutamol given via Turbuhaler and Diskus dry powder inhaler devices

The environmental concerns surrounding the use of chlorofluorocarbons (CFC) have led to a resurgence of interest in dry powder inhaler devices. The aim of our study was to compare two commonly used dry powder inhaler devices, namely the Turbuhaler and Diskus.

Eight healthy volunteers with a mean (SEM) age of 21 years (0.8) were studied using a randomised single-investigator blind crossover design. Single doses of 1.2 mg salbutamol as Turbuhaler (12 x 100 micrograms) and Diskus (6 x 200 micrograms) were administered over 6 min. Mouth rinsing was performed after every inhalation. Lung delivery from each device was assessed by measuring the early plasma salbutamol profile at 5, 10, 15 and 20 min after inhalation.

Significant differences in lung delivery were found between the Diskus and the Turbuhaler for salbutamol Cmax 3.21 vs 4.04 ng.ml-1, respectively and Cav 2.65 vs 3.73 ng.ml-1, respectively. This amounted to a 1.28-fold difference (95% CI 1.09 to 1.45) between these devices for Cmax and a 1.42-fold difference (95% CI 1.57 to 1.66) for Cav.

We have demonstrated that, in vivo, the Turbuhaler dry powder inhaler produces significantly greater lung delivery of salbutamol than the Diskus. This illustrates that dry powder inhaler devices may have different in vivo deposition characteristics.