Thiol-Based Drugs in Pulmonary Medicine: Much More than Mucolytics

Thiol-based drugs are considered as mucolytics because they decrease the viscosity and mostly decrease the elasticity of bronchial secretions by reducing disulfide bonds in proteins. However, they can also act as antioxidant drugs directly through free sulfhydryl groups that serve as a source of reducing equivalents, as well as indirectly through the replenishment of intracellular glutathione (GSH) levels. Modulation of neurokinin A levels may also be related to the effect of thiol drugs on oxidative stress. Moreover, thiol-based drugs interfere with inflammatory pathways and modulate human bronchial tone. They might also be considered as therapeutic agents against some types of infection because they reduce bacterial adhesion to the respiratory epithelial cell surface and inhibit biofilm formation, causing biofilm disruption and thereby improving the efficacy of antibiotic therapy.