Clinical Research Directory

Inclusion Criteria: 1. Male or female patients aged 12 to 75 years, inclusive. 2. Acute bronchitis with onset within 48 hours before randomization and BSS total score \>=5 at both screening and randomization. 3. Females of childbearing potential and males agree to medically acceptable contraception during the trial: ovulation-inhibiting combined hormonal contraception (oral, intravaginal, or transdermal); ovulation-inhibiting progestogen-only contraception (oral, injectable, or implantable); intrauterine device; intrauterine hormone-releasing system; bilateral tubal ligation/salpingectomy; bilateral oophorectomy; vasectomized partner; or sexual abstinence. 4. Negative pregnancy test before study medication in females of childbearing potential. 5. Voluntary written informed consent after explanation of the study. A legally authorized representative also provides written consent for participants younger than 19 years. Exclusion Criteria: 1. Body temperature \>38.5 degrees Celsius at randomization. 2. Respiratory disease that could affect efficacy assessment, including pneumonia, bronchial asthma, cystic fibrosis, viral influenza, active tuberculosis, chronic obstructive pulmonary disease, bronchiectasis, or interstitial lung disease; or suspected pneumonia on chest radiography, auscultation, or vital signs. 3. Medical history or disease judged to affect the study, including a coagulation disorder, increased bleeding tendency, or abnormal coagulation test at screening; malignancy within 5 years (exceptions include completely excised basal/squamous cell carcinoma, radically resected papillary thyroid carcinoma, or successfully treated cervical carcinoma in situ at least 1 year previously; patients considered cured within the previous 5 years with no subsequent treatment or anticipated need for treatment may participate); or clinically significant hepatic, renal, cardiovascular, respiratory, endocrine, or central nervous system disease or disorder. 4. History of psychiatric illness, alcoholism, or drug abuse. 5. Hereditary galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption. 6. Use or planned use of prohibited medication: anticoagulants at screening; systemic antibiotics/antivirals or systemic/inhaled glucocorticoids from 2 weeks before randomization through the final visit; ACE inhibitors from 1 week before randomization (4 weeks for perindopril) through the final visit, except stable dosing for an underlying condition; expectorants, mucolytics, antitussives, or herbal antitussive/expectorant products from 2 days before randomization through the final visit; or antihistamines, anticholinergics including bronchodilators, other symptomatic treatments for acute bronchitis, or analgesics throughout the study. Temporary acetaminophen for fever up to 1.5 g/day is permitted, except within 24 hours before Visits 2 and 3. 7. ALT or AST \>3 times the upper limit of normal, or estimated glomerular filtration rate \<30 mL/min/1.73 m2 calculated using the CKD-EPI equation. 8. History of hypersensitivity to study medication ingredients. 9. Pregnancy or breastfeeding. 10. Average smoking of at least 15 cigarettes/day during the preceding 30 days. 11. Receipt of investigational medication or an investigational device in another trial within 30 days before screening, or current participation in another interventional trial. 12. Any other reason judged by the investigator to make participation inappropriate.