Efficacy and Safety Study of Procaterol Hydrochloride to Treat Patients With Cough Variant Asthma (CVA)

• Patient cough symptom score [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
• Therapy duration [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]
• Rates of adverse events [ Time Frame: 8 weeks ] [ Designated as safety issue: Yes ]

The purpose of this study is to investigate the efficacy and safety of procaterol hydrochloride with inhaled glucocorticoid in treatment patients with cough variant asthma (CVA).

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.

• Drug: Procaterol hydrochloride
  25µg BID for 8 weeks
  Other Name: Meptin
• Drug: Meptin placebo
  25µg BID for 8 weeks
  Other Name: Meptin

• Experimental: I. Procaterol Hydrochloride
  Meptin (Procaterol hydrochloride) Tablets, 25µg twice daily orally plus inhaled budesonide 200µg twice daily for eight weeks;
  Intervention: Drug: Procaterol hydrochloride
• Placebo Comparator: II. Procaterol hydrochloride placebo
  Meptin placebo (Procaterol hydrochloride) Tablets, 25µg twice daily orally plus inhaled budesonide 200µg twice daily for eight weeks;
  Intervention: Drug: Meptin placebo

Inclusion Criteria:

• male or female patients,18-75 years old;
• cough lasting over 3 weeks ; dry cough or with slight white mucous phlegm; cough is the main clinical symptom or the only symptom;
• without wheeze and fever;
• without the history of upper respiratory tract infection within recent two months; non-smoking or giving-up smoking for over two years;
• without rales from lung;
• no obvious abnormalities from chest X-ray;
• bronchial provocation test: positive.

Exclusion Criteria:

• patients with chronic pulmonary disease;
• patients who are allergic to ß2 receptor agonist;
• patients taking ß2 receptor agonist for long time;
• severe heart, renal and hepatic disease;
• unable to comply with the protocol;
• pregnant, breast feeding, and childbearing potential women;
• patients improper to the trial according to the investigators' judgment.