Acute toxicity of long-circulating and pH-sensitive liposomes containing cisplatin in mice after intraperitoneal administration.

AIMS: The objective of this work was to evaluate the acute toxicity of long-circulating and pH-sensitive liposomes containing cisplatin (SpHL-CDDP), after their intraperitoneal administration in male and female mice. MAIN METHODS: After single administration of free CDDP (5,10,and 20 mg/kg) or SpHL-CDDP (7,12,30,45 and 80 mg/kg), the body weight was recorded and the LD(50) was calculated. Blood samples were collected for biochemical and hematological analysis. Kidneys, liver, spleen and bone marrow were removed to histopathological examination. KEY FINDINGS: Mice treated with high doses of free CDDP showed a greater loss of body weight and more delayed recovery time than those treated with SpHL-CDDP. The LD(50) values for SpHL-CDDP treatment for male and female mice groups were 2.7 and 3.2 fold higher, respectively, than that obtained for free CDDP. The red and white blood cells counts and quantification of hemoglobin and hematocrit presented no change upon administration of SpHL-CDDP treatment. Free CDDP treatment, however, did lead to an appearance of mild anemia and a reduction in total white blood cell counts. As regards nephrotoxicity, it was observed that free CDDP treatment caused pronounced alterations in the blood urea and creatinine levels of mice. In contrast, these parameters were slightly altered only after SpHL-CDDP treatment at a dose of 30 mg/kg. Microscopic analysis of kidneys from mice treated with SpHL-CDDP showed no morphological alteration. Concerning hepatotoxicity, no histopathological alteration was observed after both treatments. SIGNIFICANCE: These findings reveal that SpHL-CDDP can eliminate CDDP-induced toxicity and is thus a promising candidate for intraperitoneal chemotherapy.

Tissue distribution evaluation of stealth pH-sensitive liposomal cisplatin versus free cisplatin in Ehrlich tumor-bearing mice.

Multidrug resistance and drug toxicity represent major obstacles to cancer chemotherapy. Drug delivery systems, such as liposomes, offer improved chemical stability of encapsulated drugs, enhanced accumulation in tumors and decreased toxicity. The aim of this study was to evaluate the tissue distribution of stealth pH-sensitive liposomes containing cisplatin (SpHL-CDDP), compared with free cisplatin (CDDP), in solid Ehrlich tumor-bearing mice. After administering a 6 mg/kg single intravenous bolus injection of either free radiolabeled cisplatin or SpHL containing radiolabeled cisplatin, blood and tissues were analyzed for cisplatin content by determining radioactivity using an automatic scintillation apparatus. The area under the CDDP concentration-time curve (AUC) obtained for blood after SpHL-CDDP administration was 2.1 fold larger when compared with free CDDP treatment. The longer circulation of SpHL-CDDP led to a higher tumor AUC, and the determination of the ratio between AUC in each tissue and that in blood (Kp) showed a higher accumulation of CDDP in SpHL-CDDP administrated tumors. The SpHL-CDDP was also significantly uptaken by the liver and spleen. The distribution of SpHL-CDDP in these organs was extensive, revealing a high extravasation of CDDP to the tissues. The SpHL-CDDP kidney uptake was also greater than that of free CDDP; however, the Kp value found was lower. This indicates that the SpHL-CDDP led to a reduction of CDDP retention by renal tissue. Thus, these results indicate that the SpHL-CDDP may indeed be useful in alleviating renal damage induced by CDDP and thus represents a promising delivery system for cancer treatment through CDDP.