The Safety, Feasibility, and Repeatability of Inhaled ATP Cough Challenges
The inhalation of adenosine 5'-triphosphate (ATP) to evoke cough (ATP cough challenge) is becoming increasingly used as a tool to measure cough hypersensitivity in patients with chronic cough. However, the safety, feasibility, and repeatability of this procedure is not widely known. In this study, we will perform ATP cough challenges in healthy individuals and in patients with mild asthma and chronic cough to better understand the safety, feasibility, and repeatability of these challenges. Such information will guide the future conduct of ATP cough challenges to measure cough hypersensitivity and identify patients who may better respond to ATP-blocking therapies.
∙ Eligible participants in Phase 1 will include healthy adults (≥18 years old) with:
• Normal spirometry; and
• No current or past medical history of chronic cough or other respiratory diseases.
∙ Eligible participants will include adults (≥18 years old) with:
• RCC/UCC for \>1 year, demonstrated by a normal chest radiograph and no airflow obstruction (FEV1/FVC\>0.7/LLN) with either:
‣ Insufficient improvement in cough despite treatment targeting any underlying condition(s) contributing to the cough (RCC); or
⁃ Cough for which an underlying cause has not been determined despite thorough investigation (UCC).
• Mild steroid-naïve asthma who demonstrate evidence of a positive screening methacholine (PC20\<16 mg/mL); symptoms of cough, shortness of breath, chest tightness, and wheeze, that, in the opinion of the qualified investigator, are well-controlled; and those have not used inhaled or oral corticosteroids for the past month.