This study is exploring a new medicine called HBI-002, which is a liquid form of carbon monoxide, for people with Parkinson's disease. Parkinson's is a brain disorder that affects movement. Scientists believe that low levels of carbon monoxide, like those from smoking, might help people with Parkinson's without the bad health effects of smoking. The study lasts around 7-10 weeks and involves taking medicine for 2 weeks. You will have study visits and need a care partner who can stay with you for 4 hours after you take the medicine.

• Participants must be 40-80 years old and not have smoked for 5 years.
• The study includes several visits and a lumbar puncture to collect spinal fluid for testing.
• All study-related expenses are covered, and you and your care partner will receive a small payment for some visits.