The aim of this clinical trial is to evaluate the antitussive effect of "Theobromine capsule 300mg" in patients with acute bronchitis.

This study is double blinded, randomized, parallel designed, phase III clinical trial to evaluate the efficacy and safety of "Theobromine capsule 300mg" versus "Levodropropizine syrup" in patients with acute bronchitis.

Inclusion Criteria:

1. Patient who decided to participate in this clinical trial at his(her) own will and agreed in written letter of consent.
2. Adult aged over 18
3. Patient who has cough symptom caused by acute bronchitis
4. Patient who go to see the doctor for severe cough at his(her) own will
5. DCS score at screening vist sould be over 3.
6. For fertile woman, HCG test at screening visit shloud be negative.

patient who will continue to cough more than 1 week.(by physician's judgment)

Exclusion Criteria:

1. Patient who is accompanied by the seriously abnormal symptom in respiratory system, such as Acute infectious Pulmonary Disease, Tuberculosis, asthma.
2. Chronic bronchitis including bronchial obstruction
3. Patient who has clinical history of sensitivity to Xanthine drug.
4. Patient who has Peptic Ulcer
5. 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.
6. Patient whose heart function is abnormal: including the case of showing abnormal EKG test value that is clinically significant.
7. patient who has convulsion or alcoholism.
8. Patient who has experience to have participated in other clinical trial within two months before starting the trial.
9. Pregnant woman, lactating woman.
10. Patient who thought to be cured within 3 days without any medicine.