M34 Complete delivery of medication from a valved holding chamber is affected by chamber capacity

Abstract

Aim Inhaled corticosteroid medication is the gold standard for the treatment of underlying inflammatory disease associated with asthma. Valved holding chambers (VHCs) are often prescribed to optimize fine particle delivery to the lungs whilst minimizing oropharyngeal deposition which is associated with both topical and systemic adverse events. Large volume VHCs have capacities greater than can be emptied in a single breath. This laboratory-based study compared a widely prescribed large and small volume VHCs for the delivery of pMDI-delivered fluticasone propionate (FP). Method The large and small volume VHCs (n=3 devices/group) were represented by the 750 mL Volumatic* and 149 ml antistatic AeroChamber Plus* Flow-Vu* VHC. Each VHC was connected to a breathing simulator mimicking a tidally breathing adult (tidal volume=500 mL, rate/min=13; inspiratory: expiratory ratio 1:2). A filter collected the medication delivered at the exit of the chamber. 1-actuation of FP (125 mg/actuation) was delivered to the VHC, and the mass collected on the filter after 1 complete breathing cycle (n=5 replicates) was assayed by HPLC. The procedure was repeated after 2, 3, 5, 8 and 10 breathing cycles. Results Performance measures (mean ±S.D.) are summarized in table 1. Differences in particle transport through the two different sizes of VHC investigated may have been partly responsible for the observed behavior. Another possible explanation for the lower and erratic performance with the Volumatic VHCs relates to the likely presence of electrostatic charges acquired on the internal surface of that VHC through normal handling even though pre-washing was undertaken. Other potential reasons for variability in data may relate to inhalation valve performance. Conclusions An effective VHC should be able to deliver sufficient medication in as few inhalations as possible and maintain the availability of medication for inhalation if multiple inhalations (and therefore more time) are required to empty. Using the smaller volume VHC appears to enable a larger and quicker delivery in this study.