177Lu is a lanthanide radionuclide. In recent years, the possibility of applying a drug based on the 177Lu radionuclide as a palliative treatment for bone metastases has increased. 177Lu has many prospects in terms of its applications in nuclear medicine. The high-energy beta particles and the relatively short half-life of the radionuclide are used to provide an effective treatment. In this work, a comparison of organ and tissue doses is performed with two different drugs: 177Lu in an ionic radionuclide form and 177Lu labeled methylene diphosphonate (177Lu-MDP). 177Lu in an ionic form actively accumulates in the liver and bones. Phosphonate compounds form stable radio-labeled complexes. This suggests that 177Lu-MDP is a non-dissociated form of the drug. The distribution and elimination of the drug occur according to the kinetics of the carrier, i.e., methylene diphosphonate. It is shown that the use of an osteotropic complex (describing any drug that is attracted to and targets bone) allows for the concentration of a large dose in pathological areas and minimizes damage to healthy organs and tissues.