**2.6 Toxicology investigation**

Healthy mice were given CPX1, CPX2 or free DOX to examine their toxicity. CPX1, CPX2 and DOX were intravenously injected into animals at the doses of 20 mg DOX/kg body weight and 30 mg DOX/kg body weight. The changes of their body weights were examined every day for one week. The mortality of the animals was also calculated. For histological examination, different tissues were harvested at the 4th day after the drugs were given and sectioned and analyzed by hematoxylin and eosin staining. Animal plasma activity of alanine transaminase (ALT) and creatine kinase (CK) were determined for the evaluation of the functions of livers and hearts.
