Expectorant (thins and mobilizes airway secretions)
A named clinical ACTION, not a molecular target: increases the volume and reduces the viscosity of airway secretions so cough clears them more easily
Guaifenesin’s own mechanism remains unclear — a gastric vagal reflex raising respiratory-tract fluid is the leading proposal, and trial results conflict (Ohar 2019)
Not a mucolytic: nothing here cleaves mucin disulfide bonds
Drugs with this mechanism (1)
Guaifenesin — OTC expectorant; NMDA antagonism is incidental to its unclear clinical action.