AN ISOTOPIC METHOD FOR ASSESSING THE PERF ORMANCE OF THE PNEUMATIC NEBULIZER NL9 ATOMISOR(R) IN THE PRODUCTION OF AEROSOLS FOR COLISTIN, TOBRAMYCIN AND AMILORIDE

The objective of this study was to assess the performance of a new pne umatic nebuliser NL9 Atomisor(R). The performance was assessed in term s of particle distribution, fraction nebulised, fraction inhaled and p ercentage of particles of a diameter of between 1 and 4 microns for th e nebulisation of physiological serum, colistin, tobramycin and amilor ide. The solutions were nebulised in the approved formula for their re constitution as used in the clinic after the addition of sodium pertec hnicate. The validity of this indirect isotopic method has been shown before. The nebuliser was coupled, during the nebulisation, to a pump respirator with six settings. The fraction nebulised was defined as th e percentage of the volume of the solution which had left the aerosol generator at the end of the nebulisation. The fraction inhaled was def ined as a percentage of the volume of the solution which was gathered at the end of the nebulisation on a filter placed in the inspiratory c ircuit of the aerosol generator. The study of the distribution of aero sol particle sizes was carried out using a cascade impactor at ten sta ges. Each of these parameters was determined in triplicate for the fou r solutions studied. The nebulised fraction consisted of between 33.5 and 58.6% (mean 49.7+/-8.1%). The inhaled fraction consisted of betwee n 14 and 30.4% (mean 24.5+/-5.5) and the duration of nebulisation was between 10 and 20 minutes. The MMAD was between 1.6 microns with tobra mycin 3.5 microns with physiological serum. The deposits on the 8 micr on disc of the cascade impactor for the physiological serum was respec tively 16.4, 27.1, 28.5% and for colistin 16.6, 18.5, 19.2% and with t obramycin 11.3, 16.7, 18.5% and finally for amiloride 19.9, 21.3 and 2 2%. The percentage of particles of a diameter between 1 micron and 4 m icrons was on average 64.3+/-4.4%. The different results determined be tween physiological serum and the three drugs could be linked to the d ifferent surface tensions of the solutions. This underlines the need t o characterise the performance of a nebuliser with the molecules which are destined to be nebulised. The stable performance of the NL9 Atomi sor(R) are optimal on the scanner for peripheral deposition of the aer osol which is the objective required for colistin, tobramycin and amil oride. The machine is easy to use on account of the compressor and is also easy to maintain and the material is adapted for use in the treat ment of patients siffering from mucovisdosis.