This study is for therapeutic confirmation of AG1321001 to evaluate the safety and efficacy as an anti-tussive agent in cough patients.

Inclusion Criteria:

1. Adult between the ages of 18 and 70.
2. Patient who has cough symptom caused by following diseases: chronic bronchitis, bronchiectasis, gastroesophageal reflux disease, postnasal drip syndrome caused by rhinitis, sinusitis, rhinopharyngitis, rhinolaryngitis.
3. Patient requiring internal treatment due to cough symptom, who has coughing more than 3 weeks.
4. patient who will continue to cough more than 1 week.(by physician's judgment)
5. Patient who decided to participate in this clinical trial at his(her) own will and agreed in written letter of consent.
6. Patient who is trustworthy, ready for cooperation and observing the restrictions during the trial period.

Exclusion Criteria:

1. Patient who is accompanied by the seriously abnormal symptom in respiratory system, such as Acute infectious Pulmonary Disease, Tuberculosis.
2. Patient who has clinical history of sensitivity to Xanthine drug.
3. Patient who has Peptic Ulcer or Asthma (Except Cicatrix)
4. Patient whose liver or kidney function is seriously abnormal: Including the cases of sGOT, sGPT, bilirubin and blood creatinine value exceeding twice of their upper normal limit.
5. Patient whose heart function is abnormal: including the case of showing abnormal EKG test value that is clinically significant.
6. Patient who has experience to have participated in other clinical trial within two months before starting the trial.
7. Pregnant woman, lactating woman.
8. patient who has convulsion or alcoholism.
9. patient who take medicines which can not use combination with AG1321001.