Inclusion Criteria:
1. Male and non-pregnant, non-lactating female subjects aged between 18 to 65 years (both ages inclusive)
2. Stable mild asthmatics based on National Asthma Education and Prevention Programme (NAEPP) guidelines
3. Subjects who were diagnosed by physician with mild asthma at least 6 months prior to screening visit date
4. Pre-bronchodilator forced expiratory volume in one second (FEV1) ≥ 80% of predicted
5. Airway responsiveness to methacholine demonstrated by pre-albuterol-dose (baseline) PC20 less than or equal to 1.56 mg/mL using AeroEclipse II BAN and 1-minute tidal breathing method at Screening MCT A
6. The ≥20% reduction in FEV1 at Screening MCT A relative to post-saline FEV1 should be obtained above the lowest methacholine concentration
7. At Screening MCT-B, subjects should have at least four-fold increase in PC20 over Screening MCT-A
8. At Screening MCT -B, the ≥ 20% reduction in FEV1 relative to post saline FEV1 must be obtained up to methacholine concentration 24.96 mg/mL
9. Non-smokers for at least six months prior to screening visit and a maximum smoking history of five-pack years (the equivalent of one pack per day for five years)
10. Women of child-bearing potential or women who are less than or equal to 1 year postmenopausal prior to screening visit must have negative result for urine pregnancy test
11. Women of child-bearing potential or women who are less than or equal to 1 year postmenopausal prior to screening visit must agree to the use of a reliable and medically acceptable method of contraception throughout the duration of the study
12. Women of child-bearing potential or women who are less than or equal to 1 year postmenopausal prior to screening visit using hormonal contraception must be on the same hormonal contraceptive for at least thirty days before the screening period and must be continued same throughout the study.
13. Able to provide signed written informed consent and willing to comply with all aspects of the clinical study protocol
Exclusion Criteria:
* 1.Subjects with FEV1 \< 1.5L during methacholine challenge test 2.Evidence of upper or lower respiratory tract infection (e.g., pneumonia, bronchitis, sinusitis) within six weeks prior to the study.
3.History of seasonal asthma exacerbations, in which case the subject should be studied outside of the relevant allergen season 4.History of cystic fibrosis, bronchiectasis or other respiratory diseases other than asthma (e.g., COPD, interstitial lung disease) 5.Treatment in an emergency room or hospitalization for acute asthmatic symptoms within past three months prior to screening visit 6.Need for daily oral corticosteroids within past three months prior to screening visit 7.History of life-threatening asthma leading to hospitalization within the past 1 year prior to screening visit 8.Known intolerance or hypersensitivity to any component of the albuterol metered dose inhaler (MDI) 9.Uncontrolled hypertension (systolic BP \>200 mmHg, or diastolic BP \>100 mmHg) 10.History or evidence of myocardial infarction or stroke 11.History of known aortic aneurysm 12.Current use of cholinesterase inhibitor medication (for myasthenia gravis) 13.Clinically significant ECG recording at screening such as flattening of T wave, prolongation of QTc interval (\>450 milliseconds), and ST segment depression, which in the opinion of the Investigator, would compromise subject's safety or interfere with the study results 14.History of recent eye surgery or intracranial pressure elevation risk 15.Uncontrolled diabetes (HbA1c ≥9%) at screening 16.Evidence or history of clinically significant disease or abnormality including congestive heart failure, uncontrolled artery disease, cardiac dysrhythmia, or ECG with evidence of ischemic heart disease. In addition, historical or current evidence of significant hematologic, hepatic neurologic, psychiatric, renal, or other disease or that, in the opinion of the Investigator, would put the subject at risk through study participation, or would affect the study analyses if the disease exacerbates in the study 17.Presence of any abnormal clinically significant laboratory investigation at screening visit 18.History of paradoxical bronchospasm 19.Has participated in another investigational study or device research study within 30 days before screening visit date 20.Women are pregnant, breast-feeding, or planning pregnancy during study
Period continuation criteria If subject does not meet any one Period continuation criteria at any visit of Period; retest visit will be conducted and study treatment dosing should not be administered. Period continuation criteria will be checked for maximum three visits.
If subject does not meet all Period continuation criteria at any one visit and within three consecutive visits:
At Period 1: subject should not be randomized and will be considered a 'randomization failure' At Period 2 to Period 4: subject should not administer study treatment dosing and must be discontinued from the study
1. Baseline FEV1 should not be less than 70% of predicted normal value and should be within 88 -112% of qualifying day FEV1 value.
Baseline FEV1: highest pre-saline FEV1 obtained prior to saline control test at Period MCT and which has met the acceptability criteria and have repeatable quality grade A, B, C mentioned in ATS 2019 standards Qualifying day FEV1 value: highest pre-saline FEV1 obtained prior to saline control test on qualifying day and which has met the acceptability criteria and have repeatable quality grade A, B, C mentioned in ATS 2019 standards and which has not met the retest criteria for Scr-MCT A on qualifying day
-Qualifying day: Scr-MCT A PC20 is obtained and the results of the Scr-MCT A on this day confirms that subject has met inclusion criteria 4, 5, and 6
2. Baseline FEV1 should be ≥ 1.5 L
3. Baseline FEV1 should meet FEV1 acceptability criteria as mentioned in ATS 2019 standards
4. Baseline FEV1 should meet repeatability quality grade A, B, or C as mentioned in ATS 2019 standards
5. Fall in FEV1 due to the saline control (i.e. post-saline FEV1) should not be more than 10% from the baseline FEV1 Post-saline FEV1: is the highest post-saline FEV1 value from at least one acceptable FEV1 maneuver obtained after nebulization with normal saline is completed (i.e. after saline control test is completed)
6. At least one FEV1 obtained after saline control test (post-saline FEV1) should meet acceptability criteria mentioned in ATS 2019 standards
