THE OSMOLARITY OF SOLUTIONS USED IN NEBUL IZATION

Inhaled medications are widely used in patients suffering from bronchi al diseases. Beside their pharmacological properties, nebulised soluti ons have physico-chemical characteristics that can alter bronchial rea ctivity. Non-isotonic solutions can induce a bronchial hyperresponsive ness and/or a severe bronchonconstriction. Nevertheless, multiple drug s are used for nebulisation despite their unknown osmolarity. The aim of this study was to measure the tonicity of drug solutions commonly u sed for nebulisation in patients suffering from bronchial disease. Dru g solutions were prepared either according to manufacturer recommendat ions or by diluting the stock in 5 mi of NaCl (0.9%) or H2CO3 (0.14%). Although bronchodilatator solutions (i.e. salbutamol, terbulatine, ip ratropium bromide) were nearly isotonic, some drugs prepared for nebul isation had either a very high (e.g. mesna, netilmicine) or a very low (e.g. gomenol, sodium cromoglycate) tonicity. These values may be res ponsible for bronchoconstriction. Some hypertonic solutions, prepared with drugs such as acetylcytein or netilmycin, are not commercialised for nebulisation but are commonly used for aerosol therapy. In additio n, solutions initially isotonic could become significantly hypertonic towards the end of nebulisation. Taken together these results suggest that non-isotonic solutions should be used with caution specially in p atients with bronchial hyperresponsiveness, even when aerosol therapy is prescribed for upper airways.