This is a phase II, randomised, double-blind, placebo-controlled, multicenter study to assess the efficacy and safety of HSK31858 in patients with airway mucus hypersecretion in chronic airway inflammatory diseases

Inclusion Criteria:

1)Able to fully understand and voluntarily sign informed consent; 2)Male or female patients ≥18 years of age at the time of screening; 3)Patient with chronic airway inflammatory diseases (bronchiectasis, chronic obstructive pulmonary disease, asthma); 4)24h sputum volume ≥10ml at screening period (V1) and baseline (V2); 5) If the subjects have used background therapy drugs, other background therapy drugs other than expectorant drugs were used to maintain stability for ≥1 month before screening; 6)Female subjects with fertility or male subjects whose partner is a female with fertility must agree to have no plans to have children and to use contraception voluntarily from the time of signing the informed consent form until 3 months after the last dose. All females of childbearing potential must have a negative screening pregnancy test.

7)Subjects are able to communicate well with the investigator and are able to complete the study in accordance with the protocol requirements.

Exclusion Criteria:

1. Known allergic history to the active ingredient of the investigational drug or other drugs with similar chemical structure;

2. FEV1 accounted for less than 30% of the estimated value after bronchodilator use;

3. Patients who have experienced any degree of acute exacerbation of asthma or are experiencing an acute exacerbation of asthma within 4 weeks prior to screening;

4. Hemoptysis (other than a small amount of bloody sputum or a blood clot smaller than a fingernail) occurs within 4 weeks prior to screening and requires urgent medical intervention;

5. Active infection or acute infection requiring systemic anti-infective therapy within 4 weeks prior to screening.

6. History of malignancy: subjects with basal cell carcinoma, limited squamous cell carcinoma of the skin, or cervical carcinoma in situ will be allowed to enter the study if curative treatment has been completed for at least 12 months prior to signing the informed consent form; subjects with other malignancies will be allowed to enter the study if curative treatment has been completed for at least 5 years prior to signing the informed consent form;

7. Presence of any severe and/or uncontrolled medical condition that, in the judgement of the investigator, affects the safety of the subject or interferes with the evaluation of the medication, including, but not limited to: severe neurological disease, history of serious mental disorders, major cardiovascular disease, diabetes mellitus that is poorly controlled on standardized therapy, presence of prolonged QTcF interval or cardiac arrhythmia, or immunodeficiency disorders;

8. Subjects with a history of liver disease or currently receiving treatment for liver disease during the screening period, including but not limited to acute and chronic hepatitis, cirrhosis or liver failure;

9. Uncontrolled hypertension (systolic blood pressure ≥ 160 mmHg, and/or diastolic blood pressure ≥ 100 mmHg at screening or baseline);

10. Abnormal screening and baseline laboratory tests:

    1. White blood cell count < 3 × 109/L, or neutrophil count< 1.5 × 109/L, or platelet < 70 × 109/L, or hemoglobin < 90 g/L;
    2. Alanine aminotransferase (ALT) > 2 × ULN (upper limit of normal), or aspartate aminotransferase (AST) > 2 × ULN, or total bilirubin (TBIL) > 1.5 × ULN;
    3. Patients with moderate to severe renal insufficiency (eGFR < 60 ml/min/1.73m2, calculation of eGFR using the simplified MDRD equation);

11. Participation in a clinical trial of any other drug or medical device (treated with a drug or medical device in a clinical trial) within 1 months prior to screening;

12. Having received a drug that may cause hyperkeratosis of the skin (e.g., tumor necrosis factor alpha antagonist) within 4 weeks prior to screening;

13. Patients who have used a strong inducer or inhibitor of CYP3A within 14 days or 5 half-lives prior to the first investigational product administration, whichever is longer;

14. Comorbidities associated with the development of non-hereditary palmoplantar keratoderma (e.g., myxedema, chronic lymphoedema);

15. Comorbid periodontal disease that, in the judgement of the investigator, has an impact on the study;

16. Asthmatic currently smoking subjects or subjects who quit smoking within 6 months prior to the screening visit; previous smoking subjects with a smoking history >10 pack-year = packs per day × years of smoking (Note: 1 pack = 20 cigarettes, 10 pack-year = 1 pack/day × 10 years or 1/2 pack/day × 20 years).

17. History of drug use, or substance abuse within 2 years prior to screening;

18. Pregnant, or planning to become pregnant during the study, or breastfeeding;

19. Subjects judged by the investigator to be unsuitable for participating in this trial for any reason.