Dry powder inhalation of colistin in cystic fibrosis patients: A single dose pilot study

Abstract

Background Dry powder inhalation (DPI) may be an alternative to nebulisation of drugs in the treatment of chest infections in cystic fibrosis (CF) patients. In a pilot study the feasibility of a colistin dry powder inhaler (prototype Twincer ®) by a single dose in CF-patients was assessed and compared to nebulised colistin. Methods Ten CF-patients, chronically infected with P. aeruginosa, participated in a randomised cross over study. On two visits to the outpatient clinic, patients inhaled colistin sulphomethate as 25 mg dry powder (Twincer ®) or as 158 mg nebulised solution (Ventstream ® nebuliser, PortaNeb ® compressor). Pulmonary function tests were performed before, 5 and 30 min after inhalation. Serum samples were drawn prior to each dose and at 15, 45 min, 1.5; 2.5; 3.5 and 5.5 h after inhalation. Results The DPI was well tolerated by the patients: no significant reduction in FEV1 was observed. Relative bioavailability of DPI to nebulisation was approx. 140% based on actual dose and approx. 270% based on drug dose label claim. Conclusions The colistin DPI (Twincer ® inhaler) is well tolerated and appreciated by CF-patients. Optimisation with respect to particle size and internal resistance of the inhaler is necessary to attain equivalent pulmonary deposition to liquid nebulisation.