Tolerability and physiological effects of elevated inspired carbon dioxide (CO2) concentrations in human volunteers

1. Age of 18 to 35 years (inclusive);

2. Body Mass Index (BMI) between 18 and 25 kg/m2 (inclusive) and body weight between 50 kg and 100 kg (inclusive);

3. Subject is able to read and understand the written consent form, complete study‐
related procedures, and communicate with the study staff;

1. Clinically relevant abnormal history of physical and mental health, as determined by medical history taking and physical examinations obtained during the screening visit and/or prior to the administration of the initial dose of the study drug (as judged by the investigator);

2. A semi recumbent systolic blood pressure of >150 mmHg and/or diastolic blood pressure of > 90 mmHg at screening;

3. History of alcoholism or substance abuse within three years prior to screening;

4. Use of medication during the study period;

5. Subjects smoking > 10 cigarettes/day or equivalents

6. Participation in an investigational drug trial in the 3 months prior to administration of the initial dose of study drug or more than 4 times per year;

7. Any other condition that in the opinion of the investigator would complicate or compromise the study, or the wellbeing of the subject, including pulmonary disease such as a history of asthma.