A large, multi-center clinical trial testing the proton pump inhibitor omeprazole as a therapy for cough in idiopathic pulmonary fibrosis (IPF) patients seems achievable and justified, according to results of a single-center pilot trial.
The pilot study also suggests the need to screen large patient numbers and monitor adverse side effects regarding the occurrence of respiratory infections and changes in lung health and function in future trials.
Results from the pilot study were reported in the article, “Randomised, double-blind, placebo-controlled pilot trial of omeprazole in idiopathic pulmonary fibrosis,” published in the journal Thorax.
Chronic cough is a major disabling symptom affecting up to four of every five patients with IPF, and it is known to be extremely difficult to treat with conventional antitussive treatments (therapies to prevent or treat cough).
A strong association has been shown between the occurrence of cough and health-related quality of life. So, there is a need for newer, more effective antitussive treatments for IPF patients to address chronic cough and improve their quality of life.
Interestingly, IPF patients exhibit a high rate of comorbidity with gastro-esophageal reflux disease. In fact, reflux disease has been proposed as a contributing factor to chronic cough, and the overall progression and severity of disease in IPF. As such, many countries have recommended and updated medical guidelines to include the use of antacids, such as proton pump inhibitors, to treat chronic cough.
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However, there is no large-scale study evaluating the safety and effectiveness of proton pump inhibitors in treating chronic cough in IPF.
Researchers at Newcastle University, in the United Kingdom, designed a small pilot trial to assess the safety and effectiveness of the proton pump inhibitor omeprazole (20 mg capsule) in IPF patients. In doing so, the team also sought to understand whether a multi-center trial would be worthwhile and, if so, to identify barriers that should be addressed during clinical trial design to make such a study possible.
The study included 45 IPF patients, aged 40-85 years, who attended the ILD clinic at the Royal Victoria Infirmary, Newcastle. Participants were randomly split in half, and randomized to receive either oral omeprazole (20 mg; 23 patients), or matching placebo (22 patients), twice daily, before eating, for three months.
All participants were assessed for pulmonary function and quality of life using various tests, including pulmonary function tests, a 6-minute walking test, and validated questionnaires. Participants also used an ambulatory cough recorder for 24 hours. These tests were performed before and after the treatment period.
Results showed that treatment with omeprazole led to a decrease in average cough events per hour (cough frequency) compared to placebo, with omeprazole-treated participants coughing on average 4.6 times per hour, while those in the control group coughed 8.3 times per hour. However, this decrease was not statistically significant. The researchers believe it was due to the fact the groups analyzed had a small sample size.
Participant-reported outcomes, namely in terms of cough and reflux, were essentially indistinguishable between omeprazole and control groups throughout the entire study.
Concerning safety, omeprazole appeared to be safe and well-tolerated by patients. The adverse side effects reported were mostly evenly distributed in the two groups. However, lower respiratory tract infections were more common in the omeprazole group, though the numbers involved (six in the omeprazole group, three in the placebo group) raise the possibility that the observation arose by chance, the team noted.
Taken together, the researchers believe this work provides the foundation for a large controlled trial, although several considerations need to be taken into account to make such a clinical trial feasible.
“In summary, we believe these data support the pursuit of a larger multicentre trial to determine whether proton pump inhibitors can reduce cough in idiopathic pulmonary fibrosis and provide a suite of background information to inform rational design of such a trial,” the researchers wrote.
“Future trials should be large enough to mitigate risks to recruitment, and should specifically incorporate assessments of lower respiratory tract infection and lung function as part of safety analysis,” they added.