Combinations of colistin solutions and nebulisers for lung infection management in cystic fibrosis patients

In this work different nebulisers were investigated in order to assess their efficiency in combination with colistimethate sodium (CMS) inhalation products. Four nebulisers, namely I-neb1, Aeroneb1 Go, eFlow1 rapid and PARI LC1 Sprint were studied in terms of delivered dose (DD), drug delivery rate (DDR) and respirable dose (RD) of CMS. The goal was to provide scientific data to physicians for prescribing the most appropriate nebuliser for the CMS specific user. All the apparatuses nebulised ColiFin 1MIU/3 ml solution (80 mg of CMS) with delivered doses between 31% and 41% of the loaded amount. Aeroneb Go showed the longest nebulisation time (more than 20 min). When ColiFin 2MIU/4 ml was nebulised with eFlow rapid or PARI LC Sprint, the CMS respirable dose was 45.3 mg and 39.2 mg, in times of 5.6 and 10.8 min, respectively. I-neb, having a medication cup capacity limited to 0.4 ml, loaded with Promixin 0.4MIU/0.4 ml (32 mg of CMS), provided in a time of 9 min a RD of 21.5 mg, a value slightly higher than those obtained by nebulising ColiFin 1MIU/3 ml with the other nebulisers (range 15.9–17.6 mg). The results illustrate that the clinical outcome depends on the comparative analysis of nebulisation efficiency (respirable dose) and convenience (time), not disregarding the ratios between the amount loaded, delivered and deposited at lung level.