This medical study is testing a new inhalation medicine, **RSP-1502**, for people with **Cystic Fibrosis (CF)** and a type of lung infection. **Cystic Fibrosis** is a disease where thick mucus can build up in the lungs. The study will last 14 days, and the medicine will be given by breathing it in. After taking the medicine, participants will be checked for another 14 days. The study is "double-blind," which means neither the participants nor the researchers know who gets the real medicine or a different treatment.

**Key Points:**

• The study needs people aged 12 or older with CF and specific health conditions.
• Participants cannot have certain allergies or take specific other medications.
• Participants must agree not to use other inhaled antibiotics during certain times of the study.

People who want to join must be healthy enough, not have certain infections, and cannot be pregnant or smoking. They also need to agree to use birth control if they can have children. This study helps find out if the new medicine is safe and effective for those with CF and lung infections.