To test the hypothesis that DM could have anti-inflammatory effect and thus achieve vascular protection effect on heavy smokers.

Dextromethorphan (DM), an ingredient widely used in antitussive remedies, had been reported to reduce the inflammation-mediated degeneration of neurons. We recently found that DM can prevent vascular remodeling and neuron injury in animal models of carotid ligation and cerebral ischemia injuries, respectively. It was believed that its action was through the anti-oxidant and NADPH pathway to protect brain cells. However, the mechanism and actual effect on human vascular protection remained unclear.

To test the hypothesis that DM could have anti-inflammatory effect and thus achieve vascular protection effect on heavy smokers, this prospective study will be conducted to treat subjects with heavy smoking history with DM or not and evaluate the anti-inflammatory and the improvement of endothelial function.

Inclusion Criteria:

• healthy male volunteers who are currently smoking

Exclusion Criteria:

• personal history of hypertension or diabetes mellitus
• family history with
• documented premature cardiovascular events
• cardiovascular-associated sudden death
• total cholesterol > 240 mg/dL
• triglyceride > 200 mg/dL
• low-density lipoprotein > 160 mg/dL.