In vitro drug delivery performance of five valved holding chambers with and without facemasks

Valved holding chambers (VHCs) are essential for efficient pulmonary delivery of inhaled medication in preschool children. The numerous devices in the market vary in material, aerodynamic characteristics, volume, valve properties, and mask design. Drug delivery is affected by the VHC characteristics as well as by the age and breathing pattern of the child.

We measured the drug delivery efficacy of five VHCs widely available in the market, evaluated the effect of facemasks and tested the differences between manufacturing lots. A breathing simulator was used to mimic normal (respiratory rate [RR] 25/minute and tidal volume (V_T ) 200 mL) and obstructive (RR 50/minute and V_T 50 mL) breathing of infants and toddlers.

Salbutamol output was significantly higher with a normal breathing pattern compared to the obstructive breathing pattern in most VHCs. Without masks, the differences in the median in vitro filter doses of salbutamol were mainly from 2 to 10-fold among different types of VHCs. With masks, there was a greater than 20-fold difference in drug delivery capacity between the most and least effective devices. Most VHCs had a notable variation of performance between individual devices from different lots within the same brand.

There was an extreme variation in the salbutamol delivery performance among different types of VHCs for both normal and obstructive pediatric breathing patterns with and without masks. This magnitude of performance variability can have significant and unpredictable clinical implications.