All rights reserved. We performed the toxicity studies as well as pharmacokinetics and biodistribution of the original antitumor medicine based on analogue of human milk — Lactaptin. The results show that tested medicine can be considered safe when administered intravenously once to CD-1 mice and after repeated intravenous administration to Sprague-Dawley rats. Half-life of Lactaptin is 0.26 hours. Lactaptin, like all other medicines of protein nature, is evenly distributed in organs and tissues, with preferential accumulation in liver and kidneys. In the feces and the thyroid gland only decoy products are present.