Background. The continuous increase in lung diseases argues the identification and development of safe, effective medicinal products meant to optimize inhalation treatment methods. One of the essential stages in the development of medicines is the preclinical studies based on the use of pathological animal models, through which the pathology is simulated and the possible pharmacological or toxic effects that the substance can have on the human body are monitored [1]. Aim of the study. Evaluation of research specifics of the efficacy and toxicity of inhaled drug substances in preclinical studies. Material and Methods. Bibliographic research of scientific articles using databases ResearchGate, PubMed, Hindawi, MDPI, Environmental Issues & Policy Index, Current Contents, Medline, Sage Journals: 68 scientific articles. Results. The evaluation of the selected scientific publications shows that the basic factors in preclinical studies are the correct choice of the pathological animal model and the method of inhalation administration. Body mass, airway branching, respiratory rate are just some aspects that can influence the absorption of inhaled particles. To evaluate the effectiveness and harmlessness, two methods of inhalation administration are used. The most frequently applied method is the direct one, by using a sprayer with a long, thin needle that allows the substance to be introduced deep into the lungs (51% of the articles studied). The second method is the passive one, through nose-only exposures, of the head-only or the whole body, in specialized rooms (49% of the evaluated publications). As a rule, a large number of species are used, with the recording of the mass of each and the dose of the administered preparation. Animals are kept under observation from 2 to 28 weeks. After the administration of the drug, the concentration of the preparation in the fluid epithelial mucosa and lung tissues, as well as the plasma concentration, is determined. Also, another essential parameter is the toxicity of the preparation, that's why inhalation toxicological tests are performed: acute, sub-chronic and chronic, and the dose-effect relationship is also evaluated. Conclusion. During the evolution of the medical and pharmaceutical system, significant changes are observed in the treatment of lung diseases, from invasive methods to methods that are becoming easier to use by the patient at home, inhalant treatment also being in this category. The evaluation of multiple preclinical studies of pharmaceutical products with inhalation application indicates that this is a route of administration, through which the substance is transported directly to the site of action, with reduced systemic adverse effects and high efficacy at the lung level, avoiding the worsening of the health condition.