Published Online: March 2016
Amirav & Newhouse explain in a recent report in The Journal of Allergy and Clinical Immunology: In Practice, that since particle size is proportional to the particle diameter cubed, the difference in aerodynamic particle “size” between ultra-fine mass median aerodynamic diameter of ~1um and standard particles mass median aerodynamic diameter of ~4um is about 60-fold, thus facilitating much better penetration to peripheral airways. Ultra-fine particle inhaled corticosteroids (ICS) may be better suited for targeting the narrower peripheral airways of infants and young children. They further suggest that asthma management in this age group can be simplified and the cost of therapy reduced by allowing more easily taught dose adjustments with only a single ultrafine-particle metered dose inhaler (MDI) ICS. This could result in a significant reduction in health care costs by making it unnecessary to prescribe a combination ICS and long-acting beta-agonist inhaler when ‘‘step-up’’ is required for deterioration of asthma control. With only a single MDI and single drug to deal with, a phone call to the pediatrician or relatively straight-forward written instructions, advising patients when and how to ‘‘step-up’’ the dose, as needed, to regain control could suffice when asthma symptoms increase.
Aerosol particle size does appear to be important in the treatment of asthma, particularly in young children. Instead of relying on large particle therapy (such as ICS+LABA MDI combinations, or dry powder inhalers) children may obtain increased benefit from ultra-fine ICS aerosol medications.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.