TREATMENT

1 . A method for reducing frequency of an exacerbation of chronic obstructive pulmonary disease (COPD) in a human subject having COPD, wherein the exacerbation of COPD is a temporary worsening of one or more symptoms of COPD suffered by the human subject lasting at least two consecutive days, the method comprising administering to the human subject via inhalation two or more doses per day of a composition comprising a therapeutically effective amount of ensifentrine or a pharmaceutically acceptable salt thereof, wherein the frequency of the exacerbation of COPD is reduced by at least about 40% compared to the frequency of the exacerbation of COPD in an untreated human subject having COPD and not administered the composition.

2 . The method of claim 1 , wherein the composition is administered to the human subject as a maintenance therapy.

3 . The method of claim 1 , wherein the method reduces the frequency of the exacerbation of COPD by at least about 50% compared to the frequency of the exacerbation of COPD in the human subject prior to the administering to the human subject.

4 . The method of claim 1 , wherein the method further comprises administering to the human subject a muscarinic receptor antagonist, a beta-adrenergic receptor agonist, an inhaled corticosteroid, or a combination thereof.

5 . The method of claim 4 , wherein the beta-adrenergic receptor agonist is salbutamol.

6 . The method of claim 1 , wherein the one or more symptoms of COPD is selected from the group consisting of COPD related dyspnea, increased coughing, increased sputum volume, sputum purulence, wheezing, sore throat, cold, and fever.

7 . The method of claim 6 , wherein the exacerbation of COPD is dyspnea.

8 . The method of claim 6 , wherein the exacerbation of COPD is sputum purulence.

9 . The method of claim 1 , wherein the COPD is moderate COPD.

10 . The method of claim 1 , wherein the COPD is severe COPD.

11 . The method of claim 1 , wherein the human subject has one or more conditions selected from the group consisting of asthma, pulmonary hypertension, bronchiectasis, allergy, lung cancer, chest infection, cystic fibrosis, pulmonary fibrosis, pneumonia, hay fever, allergic rhinitis, bronchitis, emphysema, adult respiratory distress syndrome (ARDS), interstitial lung disease, tuberculosis, asthma, high serum immunoglobulin (Ig), previous tuberculosis, severe airflow obstruction, chest infection, and allergic conditions in addition to COPD.

12 . The method of claim 1 , wherein time to the exacerbation of COPD is increased by at least one month following the administering to the human subject compared to the time to the exacerbation of COPD prior to the administering to the human subject.

13 . The method of claim 12 , wherein the time to the exacerbation of COPD is increased by at least two months following the administering to the human subject.

14 . The method of claim 1 , wherein the administering to the human subject is twice per day in a first dose and a second dose.

15 . The method of claim 14 , wherein the first dose and the second dose are administered to the human subject in equal amounts.

16 . The method of claim 14 , wherein the first dose and the second dose are administered 10 to 14 hours apart.

17 . The method of claim 14 , wherein the therapeutically effective amount of the ensifentrine or the pharmaceutically acceptable salt thereof is 2 mg to 4 mg.

18 . The method of claim 14 , wherein the therapeutically effective amount of the ensifentrine or the pharmaceutically acceptable salt thereof is 3 mg.

19 . The method of claim 1 , wherein the composition is a suspension.

20 . The method of claim 19 , wherein the suspension comprises particles, wherein the particles comprise at least 90 weight percent ensifentrine relative to total weight of the particles.

21 . The method of claim 19 , wherein the suspension comprises particles, wherein the particles comprise at least 99 weight percent ensifentrine relative to total weight of the particles.

22 . The method of claim 19 , wherein the suspension comprises 3mg ensifentrine free base.

23 . The method of claim 19 , wherein the suspension comprises:

a. ensifentrine particles at a concentration of from 1 to 1.4 mg/mL;

b. polysorbate 20 (Tween 20) at a concentration of from 0.3 to 0.7 mg/mL;

c. sorbitan monolaurate (Span 20) at a concentration of from 0 to 0.1 mg/mL;

d. sodium dihydrogen phosphate dihydrate at a concentration of from 0.5 to 1 mg/mL;

e. disodium hydrogen phosphate dihydrate at a concentration of from 0.5 to 1 mg/mL;

f. sodium chloride at a concentration of 5 to 10 mg/mL; and

g. water.

24 . The method of claim 19 , wherein the suspension comprises:

a. 1.2 mg/ml ensifentrine;

b. 0.5mg/ml polysorbate 20;

c. 0.05 mg/ml sorbitan monolaurate;

d. 0.744 mg/ml sodium dihydrogen phosphate dihydrate;

e. 0.853 mg/ml disodium hydrogen phosphate dihydrate;

f. 8.6 mg/ml sodium chloride; and

g. water.

25 . The method of claim 1 , wherein the administering to the human subject is via a nebulizer.

26 . The method of claim 1 , wherein the administering to the human subject is via a pressurized metered dose inhaler (pMDI).

27 . The method of claim 1 , wherein the administering to the human subject is via a dry powder inhaler (DPI).

28 . The method of claim 1 , wherein the exacerbation of COPD is a moderate exacerbation as determined by the human subject requiring treatment with oral and/or systemic corticosteroids and/or antibiotics as a result of the exacerbation of COPD.

29 . The method of claim 1 , wherein the exacerbation of COPD is a severe exacerbation as determined by the human subject requiring hospitalization as a result of the exacerbation of COPD.