Improved pharmacological profile of the lipophilic antitumor dichloro-(N-dodecyl)-propanediamine-platinum(II) complex after incorporation into pegylated liposomes.

ABSTRACT

Liposome encapsulation of platinum (Pt) drugs has emerged as a promising strategy to overcome their toxicity and cellular Pt resistance. The aim of the present work was to examine the impact of liposome encapsulation of a novel antitumor lipophilic Pt complex, dichloro-(N-dodecyl)-propanediamine-platinum(II) complex (DDPP), on its pharmacological profile as an antitumor agent. Biological assays included acute toxicity and histopathological evaluations, pharmacokinetics, and growth inhibition of B16-F1 tumor cells in C57Bl/6 mice. Comparison was made with cisplatin and free DDPP dissolved in castor oil. DDPP encapsulated in pegylated liposomes showed reduced acute toxicity in mice following intraperitoneal administration, compared with the free complex. Free DDPP at 5 mg Pt/kg induced histopathological alterations in the liver, in contrast to liposomal DDPP and cisplatin. Interestingly, the marked loss of body weight following the treatment of mice with cisplatin was not observed after liposomal DDPP at the same Pt dose. Liposomal DDPP was found to inhibit tumor growth significantly, when administered at 5 mg Pt/kg/day for 3 days, similar to cisplatin, but in contrast to the free complex. Pharmacokinetic studies after intraperitoneal and intravenous administrations at 5 mg Pt/kg indicated greater and more prolonged Pt levels in the plasma, liver, spleen, and kidneys from liposomal DDPP, compared with free DDPP or cisplatin. The tumor concentration of Pt increased after liposomal DDPP over the 24-h period, whereas it decreased after cisplatin. In conclusion, the encapsulation of DDPP in pegylated liposomes reduced the drug toxicity and enhanced its antitumoral activity in mice, as a result of improved drug pharmacokinetics.