Lipid cubic phases for improved topical drug delivery in photodynamic therapy.
Journal article, 2005

We have evaluated the efficacy of lipid cubic phases, highly ordered self-assembly systems on the nanometer level, as drug delivery vehicles for in vivo topical administration of delta-aminolevulinic acid (ALA) and its methyl ester (m-ALA) on nude mice skin. ALA, a precursor of heme, induces the production of the photosensitizer protoporphyrin IX (PpIX) in living tissue. Measuring the PpIX fluorescence at the skin surface, after topical administration, makes indirect quantification of the penetration of ALA into the tissue possible. Cubic phases were formed of lipid (monoolein or phytantriol), water and drug. In some cases, propylene glycol was included in the cubic phase as well. The drug concentration was 3% (w/w, based on the total sample weight) in all investigated vehicles. When the formulations were applied for 1 h, the monoolein cubic systems and the three-component phytantriol sample showed higher fluorescence compared to the standard ointment during the 10 h of measurement. Both ALA and m-ALA yielded similar results, although the differences between the investigated vehicles were more pronounced when using m-ALA. For the 24-h applications, the monoolein cubic systems with m-ALA showed faster PpIX formation than the standard ointment, implying higher PpIX levels at short application times (less than 4 h). The systemic PpIX fluorescence of ALA was elevated by using the lipid cubic formulations. Notably, a small systemic effect was also observed for the monoolein cubic sample with m-ALA. These results imply improved PpIX formation when using the lipid cubic systems, most probably due to enhanced drug penetration.

Methyl aminolevulinate


Lipid cubic phase


Aminolevulinic acid


Johanna Bender

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Marica B Ericson

University of Gothenburg

Nadia Merclin

Uppsala University

V. Iani

Rikshospitalet-Radiumhospitalet HF

Arne Rosen

University of Gothenburg

Sven Engström

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

J. Moan

Rikshospitalet-Radiumhospitalet HF

Journal of Controlled Release

01683659 (ISSN)

Vol. 106 3 350-360

Subject Categories

Pharmaceutical Sciences



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