IV Colistin for Pulmonary Exacerbations: Improving Safety and Efficacy

The purpose of this study is to find the safest and most effective way to administer IV antibiotics to treat acute pulmonary exacerbations (APEs) in patients with cystic fibrosis (CF) that are caused by pathogens, like Pseudomonas aeruginosa. This study will test the safety and effectiveness of two commonly prescribed IV antibiotics: tobramycin and colistin. Though regularly used, not much is known about how these drugs compare with each other in terms of their toxicities, both during short term treatment of an APE and after many treatment courses with these drugs over many years. There are currently no guidelines on the safest and most effective antibiotics to use when treating APEs. We will study kidney function, sputum cultures, and treatment outcomes in patients receiving routine administration of one of these two IV antibiotics. We will also test these outcomes in patients receiving a less frequent dosing schedule for IV colistin. The hope is that this new schedule for IV colistin, which is twice a day and adjusted based on blood and urine tests, will reduce harmful side effects, such as kidney damage, while still being a powerful treatment against CF microbial pathogens.

Study Overview

• Status: Completed
• Conditions: Cystic Fibrosis
• Intervention / Treatment: Drug: Colistin; Drug: Tobramycin

• Study Type: Interventional
• Enrollment (Actual): 51
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Colorado
    • Denver, Colorado, United States, 80206
      • National Jewish Health

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Male or female ≥ 18 years of age at Visit 1.

2. Documentation of CF diagnosis as evidenced by one or more clinical features consistent with the CF phenotype and one or more of the following criteria:

   • Sweat chloride equal or greater than 60 mEq/L by quantitative pilocarpine iontophoresis test.
   • Two well-characterized mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene
   • Abnormal nasal potential difference (NPD) as measured by a change in NPD in response to a low chloride solution and isoproterenol of less than -5 mV.
3. Documentation of the presence of an acute pulmonary exacerbation, based on CF Foundation guidelines, as diagnosed by a faculty member of the Denver Adult CF Program.
4. Respiratory culture(s) demonstrating evidence of Pseudomonas aeruginosa or Achromobacter species airway infection.
5. Subject is able to produce sputum, undergo phlebotomy, and provide written consent.
6. The subject's treating physician has determined that they should receive either tobramycin or colistin intravenously as one of the designated agents for their APE treatment. Subjects who are able to receive either tobramycin or colistin as part of their antibiotic regimen will be randomized into one of three arms. If a treating physician deems that a subject cannot receive tobramycin due to vestibular toxicity, ototoxicity or bacterial resistance, the subject will be randomized to either standard or PK-adjusted colistin.

Exclusion Criteria:

1. Concomitant administration of bactrim (due to effects on creatinine).
2. Concomitant administration of inhaled colistin for patients in the colistin PK arm, as this will create inaccuracies in colistin sputum concentration measurements.
3. Patients being treated for B. cepacia, due to colistin resistance by the pathogen.
4. Presence of chronic renal insufficiency, with abnormal baseline creatinine >1.2mg/dL.
5. Presence of a condition or abnormality that in the opinion of the investigator would compromise the safety of the patient or the quality of the data.
6. Inability to perform reproducible spirometry.
7. Inability to expectorate sputum. -

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Standard colistin arm; Subjects initially receive IV colistin 2.5 mg/kg/d divided into three times daily (TID) dosing. Subjects receiving colistin will undergo a 2 day up-titration of dose to an ultimate dose of 4-5 mg/kg/day, for a total treatment of 14 days. The drug is infused over 30 minutes on a TID dosing schedule.	Drug: Colistin
Active Comparator: Modified colistin arm; Subjects receiving IV colistin undergo a 2 day up-titration to a maximum dose of 5 mg/kg/day, divided into twice daily (BID) dosing, for a total treatment of 14 days. The drug is infused over 30 minutes BID. Steady state plasma concentrations on day 3 of therapy (on 2nd- 3rd dose once at goal dosing) will be measured; specifically, colistin peak (30 minutes after infusion), midpoint (6 hour) and trough (30 minutes prior to next infusion).	Drug: Colistin
Active Comparator: Standard tobramycin arm; Subjects receive IV tobramycin 8-10 mg/kg/day with once daily dosing for 14 days. Peaks and troughs are drawn with the second dose of tobramycin, and the drug is infused over 30 minutes	Drug: Tobramycin

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Absolute Change in Forced Expiratory Volume at One Second (FEV1) % Predicted Between Study Arms With Acute Pulmonary Exacerbation (APE) Treatment	absolute change in forced expiratory volume at one second (FEV1) % predicted, or percent predicted FEV1, between study arms with acute pulmonary exacerbation (APE) treatment	up to 14 days, from beginning to end of APE treatment
Rate of Occurrence of the Development of Acute Kidney Injury (AKI) During APE Treatment		up to 14 days, from beginning to end of APE treatment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Differences in Occurrences of Neurotoxicity and Ototoxicity Related Side Effects Between Study Arms as Reported by Treating Physician(s)	absolute occurrences of adverse event rates are being compared between treatment groups using logistic regression, adjusting for age, co-administration of medications such as vancomycin and trimethoprim-sulfamethoxazole, baseline FEV1, admits in the previous year, and diagnosis of CF related diabetes (CFRD) as covariates.	up to 14 days, from beginning to end of APE treatment
Longitudinal Differences in Exacerbation Rates Between Tobramycin and Colistin Use as Seen in Readmission Rate	time to next hospital admission for pulmonary exacerbation measured in days when comparing of different antibiotic therapies	from the beginning of APE treatment to 12 months after APE treatment

Collaborators and Investigators

• Sponsor: National Jewish Health
• Investigators: Principal Investigator: Milene Saavedra, MD, National Jewish Health

Study record dates

Study Major Dates

• Study Start (Actual): August 26, 2016
• Primary Completion (Actual): September 10, 2020
• Study Completion (Actual): November 22, 2021

Study Registration Dates

• First Submitted: April 12, 2016
• First Submitted That Met QC Criteria: September 26, 2016
• First Posted (Estimated): September 29, 2016

Study Record Updates

• Last Update Posted (Actual): April 28, 2026
• Last Update Submitted That Met QC Criteria: April 8, 2026
• Last Verified: March 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Respiratory Tract Diseases; Digestive System Diseases; Lung Diseases; Infant, Newborn, Diseases; Pancreatic Diseases; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Cystic Fibrosis; Peptides; Amino Acids, Peptides, and Proteins; Proteins; Lipids; Carbohydrates; Polycyclic Compounds; Glycosides; Membrane Proteins; Aminoglycosides; Macrocyclic Compounds; Peptides, Cyclic; Lipopeptides; Kanamycin; Polymyxins; Antimicrobial Cationic Peptides; Antimicrobial Peptides; Pore Forming Cytotoxic Proteins; Nebramycin; Colistin; Tobramycin
• Other Study ID Numbers: SAAVED15A0

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO