An assessment of jet and ultrasonic nebulisers for the delivery of lactatedehydrogenase solutions

The aim of this study was to investigate the suitability of commercial jet and ultrasonic nebulisers for effective delivery of the model hydrophilic p rotein lactate dehydrogenase (LDH). Two jet nebulisers (Pari LC Plus and Pa ri LC Star) and two ultrasonic nebulisers (Sonix 2000 and Omron U1) were us ed to nebulise LDH solutions and the effects on protein activity and protei n concentration determined. The size distribution of the aerosols produced, measured by laser diffraction analysis, temperature changes during nebulis ation, the time to atomise a 5 ml dose volume and the mass output of the fo ur nebulisers were compared. A twin impinger (TI) was used to collect the n ebulised protein, which was assayed for total and active protein content. T here was a large variation in the median size and size distribution of the aerosols produced by each of the nebulisers from LDH and Sorensen's modifie d phosphate buffer, and in the time taken to reach the sputtering phase of aerosolisation. During use, the concentration of LDH increased in the Omron U1 nebuliser, but did not change significantly in the others. The temperat ure of the protein solution decreased by approximately 8 degreesC during je t nebulisation but increased by 3 and 10 degreesC in the Omron U1 and Sonix 2000 nebulisers, respectively. Denaturation of LDH within the nebuliser re servoir, occurred in the order Sonix > Pari LC Plus > Pari LC Star > Omron U1, whilst the deposition of active and total protein within the stages and throat of the TI was a function of the particle size of the aerosols gener ated and the specific device used. (C) 2001 Elsevier Science B.V. All right s reserved.