Aerosolization of tobramycin (TOBI) with the PARI LC PLUS reusable nebulizer: which compressor to use? Comparison of the CR60 to the PortaNeb compressor.

Aerosol output, aerosol output rate, and aerosol size distribution are influenced by the compressed air flow rate through the nebulizer cup. Testing a nebulizer-compressor with a drug for inhalation in cystic fibrosis (CF) patients is mandatory prior to starting therapy. Tobramycin solution for inhalation (TSI), TOBI, is licensed in Europe with a recommendation for a "suitable" compressor connected to the PARI LC Plus nebulizer. To select a compressor, five devices were tested in a previous in vitro study and this resulted in a subsequent in vivo study. Two compressors [CR60 and PortaNeb (PN)] were compared in an open, randomized, crossover single dose pilot study in 10 CF patients to assess the most suitable device for inhalation of a tobramycin solution (TSI), TOBI, with the PARI LC Plus nebulizer. Lung function (FEV1 and FVC), pharmacokinetics [PK; safety (Cmax, Ctrough)], lung deposition (indirect method AUC0-6), nebulization time, and patients' experiences (questionnaire) were determined and compared. It was found that values of Cmax and AUC0-6 were higher with the CR60 than with the PortaNeb: 0.70 versus 0.54 mg/L, p = 0.005, and 2.54 versus 2.01 h.mg/L, p = 0.017, respectively. Tmax after use of the CR60 appeared earlier (0.64 vs. 0.85 h, p = 0.005). Transient airway narrowing was measured in three patients (2 x PN;1 x CR60) versus subjective chest tightness in seven patients (CR60 > PN). A shorter nebulization time for CR60 of 13.2 min compared to PN 16.1 min (p = 0.022) was observed, which was the main reason why patients preferred the CR60 (n = 7). No toxic serum levels were reached after inhalation of TSI. The CR60 compressor may seem advantageous based on a higher lung deposition and a shorter nebulization time, but a study in a large CF population to provide information on a possible higher risk of toxicity of TSI is called for.