Etanidazole in pH-sensitive liposomes: design, characterization and in vitro/in vivo anti-Trypanosoma cruzi activity

J Control Release. 2005 Apr 18;103(3):599-607. doi: 10.1016/j.jconrel.2004.12.012.

Abstract

In this work, the hydrophilic, low molecular weight and trypanocidal drug etanidazole (ETZ) was loaded in pH-sensitive liposomes (L-ETZ). Liposomes were made of dioleoyl-phosphatidylethanolamine: cholesteryl hemisuccinate (DOPE:CHEMS, 6:4, mol:mol), of 380 nm size at 14% ETZ/total lipid (w/w) ratio. To follow their uptake and intracellular fate by fluorescence microscopy, pH-sensitive liposomes were loaded with the fluorophore/quencher pair HPTS/DPX. A fast and massive delivery of the liposomal aqueous content into the cytosol of murine J774 macrophages was observed. L-ETZ vesicles were phagocytosed by both uninfected and Trypanosoma cruzi-infected macrophages. A 72% of anti-amastigote activity (AA) was demonstrated on L-ETZ-treated J774 cells, whereas the same dose of free ETZ rendered 0% AA. Endovenous administration of L-ETZ at 14 microg/mouse dose provoked significant decrease in parasitemia levels of T. cruzi-infected mice. Conversely, inoculation of a 180-fold higher dose of free ETZ failed in reducing the number of bloodstream trypomastigotes. Hence, these results point to develop systems, such as L-ETZ, designed for selective delivery of drugs to the cytoplasm of phagocytic cells, thus enhancing the efficacy of molecules considered poorly active.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Drug Carriers
  • Endocytosis / drug effects
  • Etanidazole / administration & dosage*
  • Etanidazole / pharmacology*
  • Excipients
  • Hydrogen-Ion Concentration
  • Liposomes
  • Macrophages / parasitology
  • Mice
  • Mice, Inbred BALB C
  • Microscopy, Electron
  • Microscopy, Fluorescence
  • Particle Size
  • Phagocytosis / drug effects
  • Trypanocidal Agents / administration & dosage*
  • Trypanocidal Agents / pharmacology*
  • Trypanosoma cruzi / drug effects*
  • Trypanosoma cruzi / ultrastructure
  • Trypanosomiasis / drug therapy
  • Trypanosomiasis / parasitology

Substances

  • Drug Carriers
  • Excipients
  • Liposomes
  • Trypanocidal Agents
  • Etanidazole