N-Acetylcysteine :

NAC is a precursor of the antioxidant enzyme glutathione. NAC brakes disulfide bonds in mucoproteins, resulting in liquification of mucus thus widely used as mucolytic agent.

Acebrophylline :

Acebrophylline is a compound which has been found to act as a bronchodilating, mucoregulating and anti-inflammatory drug due to its components theophylline-7-acetate and ambroxol. Theophylline-7-acetate, as with other xanthinic derivatives, has a bronchodilator effect due to inhibition of the intracellular phosphodiesterases, followed by an increase of adenosine monophosphate cyclic levels, which promote the relaxation of bronchial muscles. Ambroxol modifies the mucous gel phase of secretions by decreasing the viscosity and increasing the serous gel phase. It increases the mucociliary clearance by stimulating cilia motility. Acebrophylline inhibits phospholipase A2 and phosphatidylcholine leading to lesser production of the powerful pro-inflammatory substances like leukotrienes and tumor necrosis factor. By inhibiting the synthesis and release of these inflammatory mediators, acebrophylline reduces inflammation, a key factor in airway obstruction, especially in chronic forms.