Computational examination of degradation reactions of active drug ingredients used for pulmonary diseases

Lung diseases are one of the world's most serious health problems, causing one-sixth of deaths worldwide. In the European Union, one -eighth of all deaths per year are due to respiratory diseases, leading to at least 6 million hospitalizations. In this thesis, drug active substances used in different pulmonary diseases such as COPD( Chronic Obstructive Pulmonary Disease), which is the third most common causes of death in the world, asthma, pulmonary embolism, ipf(idiopathic pulmonary fibrosis) will be investigated. Degradation reactions of molecules to be investigated will be examined by molecular modeling methods and theoretical approaches will be proposed for reaction pathways. For this purpose, possible reactions were calculated using Gaussian09 package program. DFT method was used in the theoratical study. In this study, possible reaction paths in the reaction between drug active substances and OH radical were determined. Fragmentation reaction requires energy. Oh radicals are used to degrade drug active substances. The lowest energy molecule has the most stable structure. According to this, when we list the drug active substances from the most stable to most unstable, they are vilanterol, afatinib, tiotropium, nintedanib, dabigatran, oledaterol, formoterol, salmaterol, pirfenidone. These results will guide experimental workers and determine the mechanism of fragmentation.