Albumin, is the highly abundant protein in the plasma. The main function of protein is delivery various endogenous (fatty acid, vitamins, hormones) and exogenous compounds such as drugs. Further, human serum albumin has a very important role in distribution, free concentration and effectiveness of these compounds.

Pimethixene belongs to the group of antihistamines characterized by sedative and antitussive properties. It has shown remarkable ability to bind to receptors such as serotonin 5-HT2A and 2B, histamine H1 and muscarinic acetylcholine M2. Moreover, oral pimethixene is used to calm dry and irritating coughs in children. However, binding constants of pimetixene for human serum albumin, as the most abundant serum transport protein, have not been determined so far.

Accordingly, in the current study explored the interactions between pimethixene and human serum albumin (HSA) by the spectroscopic measurements (fluorescence spectroscopy and circular dichroism) and molecular docking method.