A blinded study in healthy volunteers to evaluate the safety of the test medicine and compare how the test medicine behaves when the dosage is increased, and when taken alone or alongside salbutamol (albuterol)

INTERVENTION: Participants will be randomised to receive a single oral dose of GDC‐6988 or placebo twice daily for 14 days (from Day 1 to Day 14). Participants will also receive a single oral dose of salbutamol twice daily, approximately 15 minutes prior to being given GDC‐6988 for 7 days (from Day 8 to Day 14). CONDITION: Cystic fibrosis (CF) ; Nutritional, Metabolic, Endocrine ; Cystic fibrosis PRIMARY OUTCOME: ; 1. Incidence and severity of adverse events, with severity determined according to the Division of AIDS (DAIDS) toxicity grading scale assessed throughout the trial from screening until discharge from the study (approximately 10 weeks); 2. Incidence and severity of vital sign, laboratory test, spirometry, oscillometry, and ECG abnormalities assessed throughout the trial from screening until discharge from the study (approximately 10 weeks); 3. Incidence and severity of spirometry and oscillometry abnormalities after salbutamol (albuterol) pretreatment assessed throughout the trial from screening until discharge from the study (approximately 10 weeks); SECONDARY OUTCOME: ; 1. Plasma concentration of GDC‐6988 and relevant pharmacokinetic (PK) parameters measured from the first dose of GDC‐6988 until discharge from the study (approximately 6 weeks); 2. Relationship between GDC‐6988 exposure and safety endpoints assessed throughout the trial from the first dose of GDC‐6988 until discharge from the study (approximately 6 weeks); INCLUSION CRITERIA: 1. Signed Informed Consent Form 2. Age 18‐55 years at time of signing Informed Consent Form 3. Ability to comply with the study protocol 4. Body mass inde Xof 18‐32 kg/m² at screening 5. Body temperature of 35‐37.5 degrees C at screening and at Day ‐1 6. Systolic blood pressure of 90 ‐ 150 mmHg and diastolic blood pressure of 50‐95 mmHg at screening and at Day ‐1. Blood pressure should be measured while the subject is in a seated position 7. Agreement to abstain from consumption of caffeine‐containing foods and beverages from 72 hours prior to clinic check‐in and during the residential stay at the clinic 8. Agreement to abstain from consumption of alcohol from 24 hours prior to clinic check‐in and during the residential stay at the clinic 9. FEV1 >80% of predicted at screening and at Day ‐1 10. Forced vital capacity (FVC) >2.0L by spirometry at screening 11. Ability to demonstrate correct