The pharmacology of ambroxol--review and new results.

The major pharmacodynamic actions of ambroxol are surfactant stimulation, mucokinetic and secretagogue activity. The therapeutic activities of the drug in animal models of the infant and adult respiratory distress syndrome (IRDS and ARDS) are reviewed. SO2 exposed rats, which exhibited increased airway resistance and work of breathing, were used as an animal model of a bronchitic syndrome. The active group was treated with 25 mg kg-1 oral ambroxol for 10 days. The airway resistance of this group (53.6 +/- 7.0 Pa.ml-1.s) was significantly lower than that of the control (81.2 +/- 11.4). Specific work of breathing was also lower in the treated group (0.26 +/- 0.02 mJ.ml-1, control: 0.35 +/- 0.029). The alleviation of airflow limitation was a consequence of subacute treatment and not of acute bronchodilatation. Treatment with the beta 2-adrenergic drug clenbuterol further improved both active and placebo groups.