Effect of adding calcium salt of ethylene diamine tetra-acetate (CaEDTA) to nebulised tobramycin on bacterial clearance and lung function in patients with cystic fibrosis with chronic Pseudomonas aeruginosa lung infections: a randomised controlled trial..

INTERVENTION: We tested if disrupting iron utilisation by Pseudomonas aeruginosa by adding the chelating agent, calcium salt of Ethylene diamine‐tetraacetate (CaEDTA) to nebulised tobramycin would enhance bacterial clearance and improve clinical outcomes in cystic fibrosis patients. Study drug: The study drug (active drug or placebo) was supplied in blinded 1·5 ml prefilled syringes which when added to 250 mg tobramycin (Tobra‐Day®) resulted in a 4 ml solution at pH 7·1. The active drug consisted of CaEDTA (75mg, 50mM final concentration) in Tris buffered solution, while the placebo consisted of Tris buffered saline. Study design: All patients received standard treatment of their pulmonary exacerbation as per their treating physician. In addition, patients were randomised 1:1 to receive either active drug or placebo. First dose of the study drug was given within the first 72 hours of initiation of intravenous antibiotics. The study consisted of three phases: (i) The inpatient phase for first 2 weeks (while on intravenous antibiotics) when participants received study drug (active drug or placebo) four times daily – twice combined with 250 mg inhaled tobramycin, and twice with 0·9% normal saline; (ii) the 2‐6 week outpatient phase during which the participants received study drug twice daily with 250 mg inhaled tobramycin. (iii) The safety phase between 6‐10 weeks, when no study drug was given. CONDITION: Cystic fibrosis;Pseudomonas aeruginosa; ; Cystic fibrosis ; Pseudomonas aeruginosa Human Genetics and Inherited Disorders ‐ Cystic fibrosis Infection ‐ Other infectious diseases Respiratory ‐ Other respiratory disorders / diseases SECONDARY OUTCOME: The secondary outcome was change in lung function (percentage predicted FEV1) in the CaEDTA group vs placebo group. Lung function was measured before the administration of the first dose of study drug and repeated at 2 weeks, 6 weeks and 10 weeks after commencement of the study drug. Change in lung function at 2 weeks, 6 weeks and 10 weeks relative to admission was analysed in CaEDTA group vs placebo group. [Secondary time points were 2 weeks, 6 weeks and 10 weeks from the time of administration of the first dose of the study drug ((active drug or placebo).] INCLUSION CRITERIA: • Male or female 6 years of age or older with a documented diagnosis of CF (positive sweat chloride test, genotype with two identifiable CF mutations) accompanied by one or more clinical features consistent with the CF phenotype. • Current pulmonary exacerbation requiring antibiotic therapy. • If older than 6 years, must be able to perform acceptable spirometric manoeuvres. • FEV1 > 25% of predicted values (if older than 6 years of age). • Positive sputum or bronchoalveolar lavage culture for Pseudomonas aeruginosa in the past 12 months. • Must be able to give informed consent or have legally acceptable representative who can give informed consent in accordance with ICH/GCP. • Females of child‐bearing potential must agree to use an acceptable method of contraception for the duration of the trial. Initially the study was planned to be conducted in children with cystic fibrosis, however due to slow recruitment, the study PRIMARY OUTCOME: The additional primary outcome was bacterial clearance of Pseudomonas aeruginosa from sputum in the CaEDTA group vs placebo group. Sputum was collected by induced sputum method before administration of the study drug and repeated at 2 weeks, 6 weeks and 10 weeks after commencement of the study drug. Sputum density of Pseudomonas aeruginosa was measured as colony factor unit/gram of sputum and change in sputum density of Pseudomonas aeruginosa relative to admission was analysed in CaEDTA group vs placebo group. [Primary time points were 2 weeks, 6 weeks and 10 weeks from the time of administration of the first dose of the study drug ((active drug or placebo). ] The primary outcome was safety and tolerability of nebulised CaEDTA in Tris buffered saline vs placebo (Tris‐buffered saline) in combination with 250 mg tobramycin,; ; Safety and tolerability of CaEDTA was assessed by both clinical and laboratory methods: ; Clinically by screening for respiratory symptoms and signs through vital signs and systems assessment (pre‐ and post first dose of the study drug). Clinical evaluation was repeated at subsequent clinic visits at 2 weeks, 6 weeks and 10 weeks from commencement of the study drug. Additional telephone calls were made at one week and 4 weeks to check safety and adherence to therapy. ; ; As the study drug was nebulised, patients were assessed for tolerability of the study drug by measuring lung function (percentage predicted FEV1) before the first dose of study drug and repeated again at 30 minutes, one hour and 2 hours after the first dose of the study drug during first visit.; ; Blood was collected at visit one before the administration of the study drug and repeated again at each clinic visit at 2 weeks, 6 weeks and 10 weeks. Blood was analysed for full blood count, electrolytes, urea, creatinine, liver function tests (alanine aminotransferase and aspartate aminotransferase), calcium, magnesium, phosphorus and iron indices (iron, ferritin, transferrin and transferrin saturation). ; ; Patients were screened for any treatment emergent adverse events (AE’s) during each visit (clinic visit and phone call visits). Details of all concomitant medications for the duration of the study were also obtained at each clinic visit. ; ; ; ; [Clinic visits were conducted on day one of commencement of the study drug and repeated again at 2 weeks, 6 weeks and 10 weeks from commencement of the study drug. Telephone calls were made at week one and week four from commencement of intervention.]