A Study of the Effect of 20 mg Ambroxol Hydrochloride on Acute Cough.

Inclusion Criteria: 1. Be informed of the nature of the study and have provided written informed voluntary consent; 2. Be able to speak, read, and understand English; 3. Be males or females, of any race, between 18 and 80 years of age, inclusive; 4. Subject has an acute cough and other symptoms consistent with a common cold or an acute upper respiratory tract infection (URTI) diagnosis deemed by the investigator based on findings from medical history review, full physical examination and vital signs; 5. The onset of symptoms must be within 72 h of study enrolment; 6. Have a Cough Severity VAS ≥ 40 mm at Screening; 7. Be in good general health (other than URTI) with no clinically relevant abnormalities based on the medical history, physical examination, and 12 lead electrocardiogram; 8. Cough at least twice to all cough challenge Agents - citric acid, capsaicin, ATP and distilled water cough challenges at baseline. 9. If a female of child-bearing potential (i.e., have not undergone a hysterectomy or bilateral oophorectomy) or not post-menopausal (defined as no menses for at least 12 months), agree to use 2 forms of acceptable birth control from Screening through to the Follow Up Visit; or if a male, they and/or their partner of child-bearing potential agree to use 2 forms of acceptable birth control from Screening through the Follow Up Visit; 10. Be able to communicate effectively with the Investigator and other study centre personnel and agree to comply with the study procedures and restrictions. \- Exclusion Criteria: 11. History of asthma or other respiratory related disease 12. Symptoms of runny nose, stuffy nose, sore throat, or sneezing due to any condition other than URTI or common cold (e.g., seasonal or perennial allergic rhinitis, sinusitis, strep throat, vasomotor rhinitis, etc.) as established by the investigator 13. Clinical features of a complication of the common cold during the physical examination at screening (e.g., otitis media, sinusitis, or pneumonia) with or without the need for systemic antibiotics 14. History of a severe cutaneous adverse reaction to any treatment; 15. Evidence of a possible bacterial infection i.e. sinus pain, purulent nasal discharge or pleuritic pain. 16. Evidence of chest infection or pneumonia 17. Fever greater than 39ºC (102ºF oral temperature) at the time of screening if, in the judgment of the investigator, the individual is too ill to participate in the study or the fever is due to reasons other than URTI 18. Demonstrate more than two coughs to inhalation of the normal saline solution during baseline challenge 19. Current smoker or individuals who have given up smoking within the past 6 months or those with \>20 pack-year smoking history; 20. Treatment with an ACE-inhibitor during the study or within 4 weeks prior to Screening 21. History of opioid use within 1 week prior to baseline; 22. Requiring concomitant therapy with prohibited medications 23. History of known or suspected allergy or hypersensitivity reactions to ambroxol (e.g., asthma, urticaria or allergic type) or any of the non-medicinal ingredients contained in the study investigational product. 24. Clinically significant abnormal electrocardiogram (ECG) at Screening; 25. Personal or family history of congenital long QT syndrome or family history of sudden death; 26. Pregnant or breastfeeding; 27. Treatment with an investigational drug or biologic within 30 days preceding the first dose of study medication or plans to take another investigational drug or biologic within 30 days of study completion; 28. Other severe, acute, or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with trial participation or investigational product administration or may interfere with the interpretation of trial results and, in the judgment of the Investigator or Sponsor, would make the subject inappropriate for entry into this trial -