In previous studies we have looked at the variability in dose between venturi jet, breath-enhanced, and mesh nebulizers. 1,2 In this study we extended the investigation to cover breath-activated nebulizers, comparing them to a representative breath-enhanced nebulizer. Here we report on a comparison of the delivered dose (DD) from the AeroEclipse II (AeroEclipse II; Monaghan Medical Corp.), a non-metered breath-activated nebulizer, the I-neb Adaptive Aerosol Delivery (AAD) System (Respironics Respiratory Drug Delivery (UK) Ltd), a metered breathactivated
nebulizer, and the LC Sprint (PARI GmbH), a breath-enhanced nebulizer. The I-neb AAD System and the AeroEclipse II nebulizer only deliver aerosol during inhalation, but the LC Sprint nebulizer also delivers during exhalation, albeit at a reduced rate. The breath-activated nebulizers claim greater reproducibility of DD. Each nebulizer was filled with 2.5 mL salbutamol sulphate (Salamol Steri-Neb, 2 mg/mL, IVAX Pharmaceuticals) and attached to an ASL 5000 breathing simulator (IngMar Medical Ltd) set to an adult breathing pattern (tidal volume = 500 mL, 10 breaths per minute, inhalation:exhalation ratio = 1:2). The AeroEclipse II nebulizer and the LC
Sprint nebulizer were driven by 6 L/min medical air and run until sputter plus 60 seconds. The I-neb AAD System was fitted with a 0.5 mL dosing chamber and run until the end of aerosol generation. Delivery period was recorded for all nebulizers. The results indicated that the breath-activated nebulizers allow for a more reproducible DD. The DD results from the 2 breath-activated nebulizers were significantly different, and a considerably greater DD was delivered from the AeroEclipse II nebulizer, compared to the LC Sprint nebulizer or the I-neb AAD System. If such differences in DD were replicated in vivo, they could be translated into clinically relevant differences in drug dose available to the patient.