Voltage-gated Na⁺ channels (VGSC, Na_V) are critically important for electrogenesis and nerve impulse conduction. Certain Na⁺ channel isoforms are predominantly expressed in peripheral sensory neurons associated with pain sensation. The expression and functional properties of Na_V in peripheral sensory neurons can be dynamically regulated following axonal injury or peripheral inflammation¹.

Ambroxol is a secretolytic compound for the treatment of respiratory diseases². It is an effective expectorant, has been shown to normalize the structure of surfactant, to prevent the infant respiratory distress syndrome, and to be effective for the treatment of bronchitis^3,4.

In addition to its effects on the respiratory system, Ambroxol is an effective blocker of neuronal Na⁺ channels⁵. In rat dorsal root ganglia, TTX-resistant Na⁺ currents were suppressed in a concentration-dependent manner with IC₅₀ values of 35.2 and 22.5 μM for tonic and phasic block, respectively. TTX-sensitive currents were inhibited with lower potency; approximately 50% inhibition with 100 μM⁵.

Ambroxol has local anesthetic properties, which make it an efficacious treatment for sore throat⁶ and to reduce symptoms of chronic, neuropathic, and inflammatory pain in vivo^7,8. Ambroxol inhibits the release of histamine, leukotrienes and cytokines from human leukocytes and mast cells⁹. It also has well documented antioxidant properties^10,11.