Aims: The effect of the electrostatic charge in plastic spacers in vivo on drug delivery to the lung of hydrofluoroalkane (HFA) salbutamol spray was studied in children.
Methods: Five children, aged 7-12 years, were included in a 3-way crossover randomised single-blind trial. Salbutamol HFA spray was delivered on 3 different study days from plastic spacers with mouthpiece. Pre-treatment of the spacers differed between study days: (a) Non-electrostatic 350 ml Babyhaler (coated with benzalkonium chloride) (b) New 350 ml Babyhaler (rinsed in water), and (c) New 145 ml AeroChamber (rinsed in water). Plasma salbutamol was measured before and 5, 10, 15 and 20 min after inhalation of four single puffs of 100 microg salbutamol. Cmax and Cav (5-20min) were calculated as a reflection of lung dose.
Results: For Cmax: (A) Non-electrostatic Babyhaler 4.3 ng ml(-1) (B) New Babyhaler 1.9 ng ml(-1) (C) New AeroChamber 1.6 ng ml(-1): AvsB (95% CI for difference 0.5-4.5 ng ml(-1)), A vs C (95% CI for difference 0.7-4.8 ng ml(-1)). The geometric mean ratio for A:B was 2.4 fold, and for A:C was 2.9 fold. The values for Cav were similar with ratios for A:B of 2.4 fold, and A: C of 4.1 fold. The nonelectrostatic Babyhaler delivered a significantly (P<0.05) higher lung dose (for both Cmax and Cav) than either of the other two spacers.
Conclusions: The electrostatic charge in plastic spacers reduces lung dose in children by more than two-fold. This is clinically significant and the use of potentially electrostatically charged spacers should be avoided.