The primary objective of the study was to assess the bioequivalence between the test product (Albuterol Sulfate inhalation aerosol 108mcg per actuation) and the reference product (Proair HFA [albuterol sulfate] Inhalation Aerosol 90mcg per actuation) under fasting conditions. Bioequivalence would be demonstrated if the 90% confidence interval for the ratios of geometric means for AUC(0-t), AUC(0-inf), and Cmax between test products and reference products were completely contained within the FDA defined acceptance range of 80.00%-125.00%.

A single-dose, randomized, open-label, two-period, two-sequence, two-treatment, single-centre, two-way crossover bioequivalence study of Albuterol Sulfate inhalation aerosol 108mcg per actuation (equivalent to 90mcg of Albuterol) and Proair HFA (albuterol sulfate) Inhalation Aerosol 90mcg per actuation was carried out under fasting conditions in healthy adults, aged 20-60 years. For each period, 60 subjects were planned to receive a single dose of albuterol inhalation aerosol (2 puffs) according to the pre-determined randomization scheme. Venous blood of each subject was drawn 22 times over the period of 24 hours. Plasma samples were collected and analysed for albuterol concentrations by LC-MS/MS. For each subject, there were 2 dosing periods, separated by a 14-day washout period. During the study, standardized meals were provided to all subjects when institutionalized.

Inclusion Criteria:

1. Healthy male and female volunteers, aged 20-60, inclusive.

2. BMI of 18.0-30.0 kg/m², inclusive. The body weight should be over 50 kg, inclusive. (BMI will be calculated as weight in kilogram [kg]/height in meters² [m²]).

3. Healthy or non-clinical significant (NCS), according to the medical history, ECG, chest X-ray and physical examination as determined by the Principal Investigator/Sub-Investigator.

4. Systolic blood pressure between 90-139 mmHg, inclusive, and diastolic blood pressure between 50-90 mmHg, inclusive, and pulse rate between 50-100 bpm, inclusive and temperature between 35.0-37.4℃.

5. Screening laboratory values within reference range or NCS as determined by the Principal Investigator/Sub-Investigator.

6. Ability to comprehend and be informed of the nature of the study, as assessed by clinical staff. Capable of giving written informed consent prior to receiving any study medication. Must be able to communicate effectively with clinical staff.

7. Willing to fast for at least 14 hours and to consume standard meals.

8. Availability to volunteer for the entire study duration and willing to adhere to all protocol requirements.

9. Agree not to have a tattoo, body piercing, or any invasive procedure and blood donation until the end of the study.

10. Never-smokers; or former smokers who have smoked ≥ 100 cigarettes in their lifetime and have not consumed any tobacco or tobacco containing products for at least 12 months prior to screening.

11. Subjects who are non-asthmatic, defined as no clinical history of asthma, allergy or atopy.

12. Able to perform special breathing using nebulizer correctly as per the required standard.

13. Subjects must fulfill at least one of the following:

    • Be surgically sterile for a minimum of 6 months;
    • Post-menopausal for a minimum of 1 year;
    • Agree to avoid pregnancy and use medically an acceptable method of contraception from screening day until 30 days after the study ends (last study procedure).

Exclusion Criteria:

1. Known history or presence of any clinically significant hepatic (e.g. active liver disease, hepatic impairment), renal/genitourinary (e.g. renal impairment), gastrointestinal, cardiovascular, cerebrovascular, pulmonary, endocrine (e.g. hypothyroidism), immunological, musculoskeletal (e.g. myopathy, rhabdomyolysis), neurological, psychiatric, dermatological, hematological disease, or any other medical conditions, unless determined as not clinically significant by the Principal Investigator/Sub-Investigator.

2. Presence of any clinically significant illness within 30 days prior to first dosing, as determined by the Principal Investigator/Sub-Investigator.

3. Presence of any significant physical or organ abnormality as determined by the Principal Investigator/Sub-Investigator.

4. A positive test result for any of the following: HIV, Hepatitis B surface antigen, Hepatitis C, drugs of abuse (amphetamines, barbiturates, benzodiazepines, cocaine, opiates, phencyclidine, tetrahydrocannabinol), breath alcohol test. Positive pregnancy test for female subjects.

5. Known history or presence of:

   • Alcohol abuse within one year prior to first drug administration;
   • Drug abuse or dependence;
   • Hypersensitivity or idiosyncratic reaction to albuterol, its excipients, and/or related substances;
   • Allergy to standardized meal provided by site and/or presence of any dietary restrictions;

6. Intolerance to and/or difficulty in blood sampling through venipuncture.

7. Abnormal diet patterns (for any reason) during the 4 weeks preceding the study, including fasting, high protein diets etc.

8. Except for screening procedures, blood donation that results in blood loss of not more than 250 ml in the past 2 months prior to first dosing; blood loss of more than 250 ml within 3 months prior to first dosing.

9. Donation of plasma by plasmapheresis within 7 days prior to first drug administration.

10. Individuals who receives an investigational drug from 2 months prior to first drug administration.

11. Consumption of products containing caffeine/methylxanthines, poppy seeds and/or alcohol within 48 hours before dosing and products containing grapefruit and/or pomelo (shown to inhibit cytochrome P450 [CYP] 3A4 activity) within 10 days prior to first drug administration.

12. Use of any medication, including oral multivitamins, herbal and/or dietary supplements within 30 days prior to first drug administration (except topical agents without systemic absorption as determined by the Principal Investigator/Sub-Investigator).

13. Females taking oral or transdermal hormonal contraceptives within 30 days prior to first drug administration.

14. Females having used implanted, injected, intravaginal, or intrauterine hormonal contraceptive within 6 months prior to first drug administration.

15. Individuals having undergone any major surgery within 6 months prior to the start of the study, unless deemed otherwise by Principal Investigator/Sub-Investigator.

16. Using tobacco products, nicotine products (patches, gum etc.) within 6 months prior to first drug administration.

17. Lactating women.