Erdosteine is a molecule with mucolytic activity. Structurally it is a thiol derivative characterized by the presence of two thiol groups. These two functional sulfhydryl groups contained in the molecule are released following first-pass metabolism with the conversion of erdosteine into its pharmacologically active metabolite Met-I. The molecule has been discovered and developed in Italy by Edmond Pharma, today it is prescribed for chronic and acute respiratory disorders in more than 40 countries worldwide. The drug is sold under several commercial names (Esteclin, Erdomed, Erdos, Erdotin etc.), as hard capsules 300 mg, dispersible tablets 300 mg, granulates for oral suspension 225 mg and powder for oral suspension 175 mg/5ml. Pharmacodynamics Erdosteine is an oral mucoactive anti-oxidant molecule, characterized by a multi-faceted pharmacological profile that may positively interfere in more than one of the pathological processes ongoing in all respiratory disorders characterized by thickened or increased mucus production, increased oxidative stress and chronic inflammation. Moreover, an important feature of the pharmacological profile of erdosteine is represented by its synergy with antibiotics. Anti-oxidant and anti-inflammatory activity Erdosteine exerts its role as anti-oxidant and anti-inflammatory thanks to the free sulphydrylc groups of its active metabolite Met I, which has a direct scavenging effect (particularly on reactive oxygen species, ROS), and it is able to bind the free radicals preventing tissue damage. Erdosteine exerts a protective role against lipid peroxidation (smokers, COPD patients) by increasing the availability of endogenous antioxidants, such as glutathione, in plasma and bronco-alveolar lavage. Antiadhesive activity Erdosteine is able to interfere with bacterial adhesion. In fact, Met I can affect the integrity of the natural intrachain disulphide bonds of pilin; the opening of this bond can induce a morphological change that interferes with the binding of bacterial adhesin (fimbriae) to receptor. The bacterial adhesion reduction is reached by Met I ad concentration similar to the plasmatic peak obtained after a single 300 mg oral administration of erdosteine. Erdosteine showed in vivo and in vitro synergistic activity with antibiotics, against bacterial adhesiveness, in patients with respiratory infections. Several clinical studies underline that, when given in combination with antibiotics, erdosteine does not interfere with their activity but improve their effects, causing an increase in therapeutic efficacy. Mucolytic activity Erdosteine shows an important muco-regulatory activity (it increases mucus production and makes it more fluid and much less thick), and positively influences the mucociliary clearance. Several studies show that erdosteine results more active compared