Aim. The work aims to prepare smart biomaterials (thermosensitive Poly(N-isopropylacrylamide)-based hydrogels cross-linked by acid-activated Lap (aLap) doped with doxorubicin (Dox) (aLap+Dox/hydrogel)), to determine and compare the indicators of its acute toxicity, and to estimate its effects on the level of generation of superoxide radicals (SR), activity of ribonucleases (RNases), ornithine decarboxylase (ODC) and gelatinase (matrix metalloproteinases-2 and -9 (MMP-2 and -9)) in liver and kidney tissues of C57Bl/6 mice. Conclusions. Dox in aLap-based/hydrogels exhibits significantly less overall toxicity compared to the traditional Dox drug. It can be explained by the successive release of the incorporated drug during the degradation of the hydrogels in the conditions of the animal organisms. Therefore, the aLap+Dox/hydrogels are the promising carriers of incorporated antitumor drugs.