This is a 8-week, double-blind, randomized, placebo-controlled study, the patients with CVA will be randomized to experimental or placebo control group.
During the screening period, eligible patients will be evaluated by cough symptom score and LCQ life quality score. After 4 and 8 weeks treatment, patients will be evaluated by cough symptom score and LCQ life quality score respectively. Adverse events will also be captured at every visit.
