Study of the Safety and Effectiveness of BC1036 Capsules to Treat Frequent Long-Term Cough

Inclusion Criteria: * Male or female aged 18 to 75 years. * Confirmed diagnosis of a persistent cough. * Leicester Cough Questionnaire score of ≤ 17 at baseline. * FEV ≥ 70% of predicted normal, at screening. See protocol Appendix 4 for formula for calculating predicted values. * Willing to use effective contraception for the duration of the study. Female subjects who are neither surgically sterilized nor post-menopausal (defined as no menses for one year or an FSH value \> 40 mIU/L) will be required to use two methods throughout the study and for 30 days after. Besides abstinence the following contraceptive methods are acceptable: hormonal (e.g. oral, injection, transdermal patch, implant, cervical ring), barrier (e.g. condom or diaphragm with spermicidal agent) or intrauterine device. If hormonal contraceptives are used they must be used from 6 weeks before the first administration of test product. Male subjects must agree to use condoms for the duration of the study and for 30 days after. * Willing and able to give informed consent and of complying with the trial assessments and any other trial procedures. Exclusion Criteria: * Pregnant or lactating females. * Major surgery within the 30 days preceding the screening visit. * Any serious infections within the 30 days prior to the screening visit. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, uncontrolled diabetes, renal or hepatic disease or psychiatric illness/social situations that would limit compliance with study requirements. * Known hepatitis B or C or human immunodeficiency virus (HIV) or syphilis seropositivity. * A history of serious adverse allergic reaction to any medication. * Treatment with another investigational medicinal product within the 30 days prior to enrollment. * Treatment with: * Systemic oral steroids within 7 days prior to randomisation at Visit 2. * Theophylline and theophylline-like agents within 7 days prior to randomisation. * Opiates or opioids e.g. codeine, dextromethorphan, within 7 days prior to randomisation. * ACE inhibitors within one month prior to the screening visit. * Depot injection of corticosteroids within 6 weeks of the screening visit. * History suggestive of febrile illness within the last 7 days prior to the screening visit. * Subjects with significant sputum production (defined as more than 5 ml (\~one teaspoon)/day on any three days in the screening period). * Current smokers or past smokers who have a smoking history of \> 20 pack years or stopped smoking ≤ 12 months prior to screening. * Any pulmonary co-morbidity such as COPD, recurrent lower respiratory tract infections (≥ 2 in the 12 months prior to screening) and bronchiectasis where cough suppression may lead to sputum retention and infection. * Any pulmonary abnormality on chest X-ray or CT scan performed in the twelve months prior to enrolment indicative of COPD, bronchiectasis etc. * Subjects diagnosed with asthma who have suffered an exacerbation requiring hospitalisation within 4 weeks prior to screening. * A history of cancer within the previous five years (excluding carcinoma in situ or nonmelanoma skin cancer treated by surgical excision). * Uncontrolled hypertension (resting systolic BP \> 170mmHg or resting diastolic BP \> 95 mm Hg). * A corrected QT interval of \> 470ms for female subjects or of \> 450ms for male subjects, calculated using the QTcF correction formula, or second degree or higher heart block on an ECG recording, at screening. * Subjects known to have a sensitivity to methylxanthines and related compounds, or known to have exhibited an allergic response or sensitivity to cocoa-based products. * History or presence of alcohol or substance abuse.