[Effects of carbocisteine on airway inflammation and related events in SO2-exposed rats]

Airway inflammation leads to secretion of abnormal mucous glycoprotein and ciliary injury. To investigate the possible usefulness of carbocisteine against airway inflammation and events related to it, we conducted a study in SO2-exposed rats of the effects of carbocisteine and ambroxol, as an active control drug, on components of mucous glycoprotein (fucose, sialic acid and protein) in bronchoalveolar lavage fluid (BALF); on infiltration and activation of inflammatory cells in BALF; on tracheal and bronchial-ciliary lesions; and on cAMP levels in tracheal and alveolar tissues. Carbocisteine inhibited or improved all SO2-induced changes tested, and dosages of 125 and 250 mg/kg b.i.d. reduced fucose, sialic acid and protein contents, inflammatory cells (as markers of inflammation), free radicals, and elastase activity in BALF, and suppressed the development of ciliary lesions of the tracheal and bronchial mucosa, while ambroxol (10 mg/kg b.i.d.) showed no such effects. In addition, carbocisteine improved cAMP levels in the tracheal and alveolar tissues. These results indicate that carbocisteine is able to prevent the development of inflammation-related respiratory disease in this rat model, and that this remission of airway inflammation may be associated with carbocisteine-induced normalization of cAMP levels in tracheal and alveolar tissues as well as with its mucoregulant and anti-inflammatory effects. In conclusion, carbocisteine has a unique mucoregulant action and inhibits SO2-induced airway inflammation in a manner different from that of ambroxol.