An assessment of jet and ultrasonic nebulisers for the delivery of lactate dehydrogenase solutions

Comment on: Devices and formulations for pulmonary vaccination

“…The high frequency waves create standing waves on the liquid surface from which droplets are released. There is a prolonged energy transfer to the solution, which has been shown to be an important cause of degradation of the active compound [1,2]. In vibrating mesh nebulizers, the piezo technology is combined with a perforated membrane (mesh) that is in contact with the solution.…”

“…Thus, they overcome many of the factors that were identified in the paper as making nebulization unsuitable for vaccine delivery. Mesh nebulizers are described and discussed more fully in papers by Kisser et al and Hardaker et al [2,3].The review also highlighted that degradation of a vaccine can occur, either due to shear forces in the jet nebulizers, or due to ultrasonic pulsing (plus heating) in the ultrasonic nebulizers. Due to the recirculation of droplets in the jet and ultrasonic nebulizers, a labile molecule can be subjected to these shear forces a number of times before it leaves the nebulizer.…”

“…Mesh nebulizers, by contrast, have no recirculation, and pass the labile molecule only once through the aerosol generation mesh; the passage through the mesh itself is subject to low shear. This makes mesh nebulizers ideally suited to delivery of labile molecules, and successful delivery, without loss of activity, has been demonstrated with a range of macromolecules and biological materials [2,[4][5][6][7][8][9][10].Another feature of nebulizers raised in the Tonnis et al review, which limited their use for vaccine delivery, was inaccuracy of dose. This can be overcome by breath activation, implementation of volumetric metering, and use of controlled breathing patterns; these features are found in the I-neb nebulizer and can result in lung deliveries of over 70% of the total inhaled drug [11].…”

“…Thus, they overcome many of the factors that were identified in the paper as making nebulization unsuitable for vaccine delivery. Mesh nebulizers are described and discussed more fully in papers by Kisser et al and Hardaker et al [2,3].…”

“…Mesh nebulizers, by contrast, have no recirculation, and pass the labile molecule only once through the aerosol generation mesh; the passage through the mesh itself is subject to low shear. This makes mesh nebulizers ideally suited to delivery of labile molecules, and successful delivery, without loss of activity, has been demonstrated with a range of macromolecules and biological materials [2,[4][5][6][7][8][9][10].…”