Topical photodynamic therapy of tumor bearing mice with meso-tetrakis (N-methyl-4-pyridyl) porphyrin loaded in ethosomes.

Photodynamic therapy is a clinically approved procedure for the treatment of neoplastic and other non-malignant diseases. Meso-tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP) is a photosensitizing agent which has been used in many applications. However, the use of TMPyP topically is limited due to its hydrophilicity. To overcome this problem, TMPyP was loaded in ethosomes. Three ethosomal formulae (A), (B) and (C) were prepared and characterized. Preparation (A) was chosen to be used in the in vitro and in vivo study, having the greatest encapsulation efficiency, the smallest size and the highest cumulative release percentage. The results of in vitro permeation study revealed that the ethosomal TMPyP was superior to the drug in the free form with permeation flux (3.92 μg cm-2 h-1). In the in vivo animal study done on Swiss albino mice, after 19 days of Ehrlich tumor implantation, the group treated with the ethosomal preparation showed significantly smaller tumor size (143.28 ± 13.2 mm3) compared to the group treated with the free TMPyP (219 ± 11.9 mm3). It showed also significant longer survival time (21 days) compared to that treated with the free drug (18.2 ± 1.2 days). Based on the obtained results, transdermal delivery of TMPyP was potentiated by incorporating it in ethosomes.