Mesh nebulizers are small, silent, portable and comply with active drug compounds. Marketed mesh nebulizers, such as NebSmart®, Micro air® NE-U22V and Aeroneb® Go, for ambulatory patients, do better in performance to jet nebulizers in terms of inhaled drug mass and particle size.
The inhalable mass is defined as the drug mass, in the form of an aerosol, produced by the nebulizer that reaches the patient's mouth. It predicts the amount of drug penetrating into the patient's airways. The particle-size distribution of the aerosol predicts the region of aerosol deposition in the patient's airways. Particles with an aerodynamic diameter of 1–5 μm have a chance of being deposited in the lungs of adult patients. The optimal particle size for children is throught to be smaller.
Mass median aerosol diameter (MMAD) is a statistical parameter that describes the aerosol size. Mesh nebulizers have been evaluated in vitro in different studies in accordance with European standards, using a filter method and a pump that models patient inhalation. The MMAD obtained with NebSmart® from Aerosoon Medical ranged 1.5–4.2 μm with salbutamol.
The inhaled fraction, expressed as a percentage of nebulizer volume loaded in the reservoir, was 37.5% for NebSmart®. The aerosol output rate was 0.39 ml per minute for NebSmart®.
The physical properties of drug formulations slightly influence the particle size produced. Vibrating mesh nebulizers are adapted to nebulize marketed drugs with a particle size adequate for lung deposition.
