Sodium channel blocker and mucolytic agent with antioxidant, anti-viral and anti-inflammatory properties. Inhibits tetrodotoxin (TTX)-resistant channels more potently than TTX-sensitive subtypes (IC50 values for tonic block are 35.2 and 111.5 μM respectively). Inhibits release of histamine, leukotrienes and cytokines from human leukocytes and mast cells.