Abstract
Chymase-positive mast cells located in distal airways play a crucial role in asthma (Balzar 2005 & 2010). A review on inhaled DSCG by Keller & Schierholz (2011) provided evidence that poor efficacy of DSCG is most probably linked with sub-therapeutic lung doses. The hygroscopic nature of DSCG causes particle growth associated with reduced lung deposition (Hiller 1980) which may explain insufficient therapeutic efficacy. Significantly higher in-vitro respirable doses were found by aerodynamic particle size assessments in a next generation impactor operated at 50% and 95% rel. humid., respectively using small droplet nebulisers compared to Intal® MDI and DPI (Keller 2007). Nebulised isotonic solutions provided better tolerability and efficacy than hypotonic Intal solution (Weiner 1988, Soferman 1990). Higher Cmax and AUC values were obtained for nebulisers compared to MDIs and DPIs (Patel 1986 & Kato 1999). Above mentioned aspects and critisism on earlier meta-analyses by Stevens 2007 were still ignored in the latest Cochrane meta-analysis by van der Wouden 2009. Recent data from a clinical trial in 48 asthmatic children (10.3±2.8 yrs, 19 girls) inhaling for 6 months either 3× daily 20 mg isotonic DSCG via an investigational eFlow® electronic nebuliser or twice daily inhaled steroids via MDI with spacer showed comparable efficacy to inhaled steroids (Basek 2010). In conclusion, in-vivo data suggest that DSCG is a safe and effective asthma controller when a highly efficient, small droplet size generating nebuliser is used. Impactor data obtained at 50% and 95% rel. humidity show that therapeutic efficacy of DSCG is strongly affected by the delivery system.
- © 2011 ERS
