Pharmaceutical Research

, Volume 32, Issue 5, pp 1585–1603 | Cite as

Formulation and Pharmacokinetics of Thermosensitive Stealth® Liposomes Encapsulating 5-Fluorouracil

  • Chantal Al Sabbagh
  • Nicolas Tsapis
  • Anthony Novell
  • Patricia Calleja-Gonzalez
  • Jean-Michel Escoffre
  • Ayache Bouakaz
  • Hélène Chacun
  • Stéphanie Denis
  • Juliette Vergnaud
  • Claire Gueutin
  • Elias Fattal
Research Paper



We optimize the encapsulation and investigate the pharmacokinetics of 5-Fluorouracil (5-FU) delivered by thermosensitive stealth® liposomes (TSLs) designed to trigger drug release upon hyperthermia using focused ultrasound (FUS).


5-FU was encapsulated into liposomes made of 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol/1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-N-PEG2000 either as a free molecule or complexed with copper-polyethylenimine. Heat-triggered drug release was evaluated using either a water bath or FUS. Formulation cytotoxicity was assessed on HT-29 cell line by MTS assay. Pharmacokinetics and biodistribution of 5-FU were evaluated in HT-29-tumor bearing mice.


5-FU was easily encapsulated using the lipid hydration method (encapsulation efficacy of 13%) but poorly retained upon dilution. 5-FU complexation with copper-polyethylenimine improved 5-FU retention into liposomes and allowed to obtain an encapsulation efficacy of 37%. At 42°C, heat-triggered 5-FU release from TSLs was 63% using a water bath and 68% using FUS, within 10 min, whereas it remained below 20% for the non-thermosensitive formulation. The MTS assay revealed that formulation toxicity arose from 5-FU and not from the excipients. In addition, 5-FU complex encapsulation into TSLs induces a reduction of the IC50 from 115 down to 49 μM. Pharmacokinetics reveals a longer circulation of encapsulated 5-FU and a more important body exposure, although tumor passive targeting is not significantly higher than free 5-FU.


Complexation of 5-FU with copper-polyethylenimine appears an interesting strategy to improve 5-FU retention into TSLs in vitro and in vivo. TSLs allow heat-triggered release of the drug within 10 min at 42°C, a reasonable time for future in vivo experiments.


5-Fluorouracil copper-polyethylenimine complex focused ultrasound pharmacokinetics thermosensitive stealth® liposomes 



14C-radiolabeled 5-Fluorouracil




5-Fluorouracil-copper-polyethylenimine complex




Copper (II) acetate monohydrate


Copper-polyethylenimine complex


Hydrodynamic diameter


Dynamic light scattering






Ethylenediaminetetraacetic acid


Enhanced permeation and retention


Fœtal bovine serum


Food and drug administration


Focused ultrasound


Gravitational acceleration


High performance liquid chromatography


Human colorectal adenocarcinoma cells


Half maximal inhibitory concentration


Low temperature sensitive liposomes


CellTiter 96® AQueous One Solution Cell Proliferation Assay


Non thermosensitive liposomes


Phosphate buffer saline


Polydispersity index


Polyethylen glycol 2 KDa


Polyethylenimine, ethylendiamine branched


Pound per square inch


Phase transition temperature


Thermosensitive liposomes


Traditional thermosensitive liposomes


Ultraviolet/visible light domains


Zeta potential



This research work was funded by Agence Nationale de la Recherche (ANR-2010-TecSan-007). Institut Galien Paris-Sud is a member of the Laboratory of Excellence LERMIT supported by a grant from ANR (ANR-10-LABX-33). Authors would like to thank A. Maksimenko for help with the tumor model and H. Bénech for help with PK analysis.

Supplementary material

11095_2014_1559_MOESM1_ESM.docx (195 kb)
ESM 1 (DOCX 194 kb)


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Chantal Al Sabbagh
    • 1
    • 2
  • Nicolas Tsapis
    • 1
    • 2
  • Anthony Novell
    • 3
  • Patricia Calleja-Gonzalez
    • 1
    • 2
  • Jean-Michel Escoffre
    • 3
  • Ayache Bouakaz
    • 3
  • Hélène Chacun
    • 1
    • 2
  • Stéphanie Denis
    • 1
    • 2
  • Juliette Vergnaud
    • 1
    • 2
  • Claire Gueutin
    • 1
    • 2
  • Elias Fattal
    • 1
    • 2
  1. 1.Univ Paris-Sud, Institut Galien Paris-Sud, LabEx LERMIT, Faculté de PharmacieChâtenay-MalabryFrance
  2. 2.CNRS UMR 8612, Institut Galien Paris-Sud, LabEx LERMITChâtenay-MalabryFrance
  3. 3.Université François-Rabelais de Tours, Inserm, Imagerie et Cerveau UMR U 930ToursFrance

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