Intermittent inhaled tobramycin and systemic cytokines response in CF patients with Pseudomonas aeruginosa

CF pulmonary guidelines recommend alternate therapy (one month on, one month off) with inhaled tobramycin for chronic Pseudomonas aeruginosa colonization in cystic fibrosis (CF). Tobramycin-inhaled powder (TIP™) is increasingly replacing time-consuming nebulizer therapy. It is unclear whether laboratory parameters change during the month off period compared with the month on therapy. Purpose: Our aim was to assess whether spirometry, lung clearance index and circulating inflammatory markers differ between on/off treatment periods. Materials and methods: A prospective pilot study evaluating CF patients treated with TIP, on two consecutive months (on/off) therapy. The evaluations were performed at the end of a month off therapy (1-2 days before the initiation of TIP) and after 28 days of treatment with TIP (1-2 days after the end of the treatment cycle). Results: Nineteen CF patients (10 males) with a mean age of 18.7±9.7 years and BMI (body mass index) of 19.62±3.53 kg/m2 were evaluated. After a month off treatment with TIP, spirometry parameters and lung clearance index remained unchanged. IL-6 increased significantly (p=0.022) off treatment. There was a non-significant change in the other inflammatory cytokines off therapy [hs-CRP, IL-8,TNF-α, α1-antitrypsin (α1AT) and neutrophilic elastase]. Conclusions: The results of lung function parameters support the relative stability of CF patients during the month off therapy; however, the difference in serum IL-6 raises the possibility of ongoing higher degrees of inflammation during the month off therapy with TIP. The small sample size and the multiple parameters evaluated preclude firm conclusions; therefore, larger multicenter studies are needed to assess the on/off treatment strategy.