Mesh nebulizers are driven by a piezo-element and use ultrasonic frequencies to vibrate the mesh. The vibration of the mesh causes aerosol generation as the liquid passes through it. Ultrasonic nebulizers, by contrast, produce ultrasonic waves directly into the solution causing aerosol to be produced at the liquid surface. Since both use ultrasonics to generate the aerosol, confusion between the 2 types of nebulizers and their differing performance can occur. It is known that ultrasonic nebulizers are unable to deliver suspension formulations such as budesonide and this perception of inability to deliver budesonide can incorrectly be assumed to be the same for ultrasonically driven mesh nebulizers.
We compared an ultrasonic nebulizer, the Flores Medical GmbH Aerosonic Mobil 3060 nebulizer, and an ultrasonically driven mesh nebulizer, the Philips Respironics I-neb Adaptive Aerosol Delivery (AAD) System nebulizer, when delivering budesonide (2 mL of 250 µg/mL fill) to highlight the performance differences between the mesh and conventional ultrasonic devices. Nebulizer performance was assessed in terms of delivered dose, delivered dose output rate, total gravimetric output, mass median diameter, mass median aerodynamic diameter, and aerodynamic particle size distribution (APSD). These performance parameters were compared for the 2 devices against the delivery of a solution of salbutamol (2.5 mL of 2 mg/mL fill).
The Aerosonic Mobil 3060 and the I-neb AAD System nebulizers delivered 714 µg and 1079 µg of salbutamol respectively. With budesonide, the Aerosonic Mobil 3060 delivered 9.2 µg and the I-neb AAD System nebulizer delivered 109 µg. APSD data indicated the low delivery by the Aerosonic Mobil 3060 was a consequence of it being unable to deliver the suspended particles.
The results demonstrated that both nebulizer types are capable of delivering solutions but that the ultrasonic nebulizer cannot effectively deliver budesonide, whereas the mesh nebulizer can.