The work demonstrates that periodontitis, which was formed against the background of experimental pneumonia (4th, 8th, 10th and 18th day) accompanied by a gradual increase of malonyl dialdehide, dienic conjugate, asocasein, asocolagen, azoalbumine and decreased activity of superoxide dismutase, catalase, glutathione peroxidase and glutathione, alpha-2-macroglobulins and alpha-1-protease inhibitor in the lungs which testifies to the development of oxidative stress, activation of proteolytic processes and inhibition of antiprotease potential. Using thiotriazoline causes correcting effect on metabolic indicators in periodontitis in experimental pneumonia.