Pharmacological study of the new mucolytic drug N-guanyl-cysteine.

The pharmacological evaluation of N-guanyl-cysteine (IQB-782) is reported. This new cysteine derivative shows a potent mucolytic-expectorant activity in different test systems. Thus, IQB-782 protects rats against tobacco-smoke-induced respiratory airway obstruction, increases the tracheo-bronchial mucus secretion in rabbits and increases the pulmonary excretion of fluorescein in mice, an index of broncho-secretagogue activity. Like other mucolytics, IQB-782 is also effective in vitro in reducing the viscosity of a suspension of gastric mucin. This new drug is apparently devoid of any cardiovascular or autonomic activity and shows a moderate CNS depressant effect. IQB-782 is consequently a new thiol derivative which may offer some advantages in the treatment of different types of obstructive pulmonary disease.