Formulation and clinical evaluation of silymarin pluronic-lecithin organogels for treatment of atopic dermatitis

Abstract

Silymarin is a naturally occurring flavonoid drug; evidence from recent research has highlighted its use as a potential treatment for atopic dermatitis (AD). Both poor water solubility and drug permeability have hindered the percutaneous absorption of silymarin. Formulation of silymarin into pluronic-lecithin organogel (PLO) basis for topical skin delivery is the main aim of this work. Six different PLO formulations were prepared containing various pluronic to lecithin ratios using two cosolvent systems of ethyl alcohol and dimethyl sulfoxide. Formulation 2 (20% pluronic and 3% lecithin) was found to be the optimal base for topical delivery of silymarin as it showed optimum pH, viscosity, drug content, and satisfactory in vitro silymarin permeation. The silymarin PLO formulation significantly relieved inflammatory symptoms of AD such as redness, swelling, and inflammation. These findings warrant the ability for application of these novel silymarin PLO formulations as a novel treatment for AD.

Keywords: atopic dermatitis; pluronic lecithin organogel; silymarin; skin penetration.

Figure 1

FTIR spectroscopy. Notes: Silymarin (A), PLO gel free base (B), drug loaded PLO gel (C). Abbreviations: FTIR, Fourier transform infrared spectroscopy; PLO, pluronic-lecithin organogel.

Figure 2

Rheology behaviors of different PLO gels loaded with silymarin. Notes: F2 to F6: using 30% ethyl alcohol as a solvent; F2^*: using 3% DMSO as a solvent. Abbreviations: PLO, pluronic-lecithin organogel; DMSO, dimethyl sulfoxide.

Figure 3

In vitro release of silymarin from different formulations of PLO gels. Notes: F2 to F6: using 30% ethyl alcohol as a solvent; F2^*: using 3% DMSO as a solvent. Abbreviations: PLO, pluronic-lecithin organogel; hr, hours; DMSO, dimethyl sulfoxide.

Figure 4

Ex vivo permeability release (XF2, XF2^*) compared with the in vitro release (F2, F2^*) of silymarin from PLO gels. Note: F2, F2^*, XF2, and XF2^*: using 30% ethyl alcohol as a solvent. Abbreviations: PLO, pluronic-lecithin organogel; hr, hours.

Figure 5

Photographs of different AD patients before and after treatment with silymarin loaded PLO gels. 0

Figure 6

Comparison between control side and treated side with regards to itching.

Figure 7

Patient’s skin histology. Notes: Before (A) and after (B) treatment with silymarin loaded PLO gels. Magnification= 100×; Scale bar= 200 μm. Abbreviation: PLO, pluronic-lecithin organogel.