Transdermal delivery of curcumin via microemulsion.

International journal of pharmaceutics (2015-02-07)
Amnon C Sintov
ABSTRACT

The objective of this study was to evaluate the transdermal delivery potential of a new curcumin-containing microemulsion system. Three series of experiments were carried out to comprehend the system characteristics: (a) examining the influence of water content on curcumin permeation, (b) studying the effect of curcumin loading on its permeability, and (c) assessing the contribution of the vesicular nature of the microemulsion on permeability. The skin permeability of curcumin from microemulsions, which contained 5%, 10%, and 20% of water content (1% curcumin), was measured in vitro using excised rat skin. It has been shown that the permeability coefficient of CUR in a formulation containing 10% aqueous phase (ME-10) was twofold higher than the values obtained for formulations with 5% and 20% water (Papp=0.116 × 10(-3)± 0.052 × 10(-3)vs. 0.043 × 10(-3)± 0.022 × 10(-3) and 0.047 × 10(-3)± 0.025 × 10(-3)cm/h, respectively. A reasonable explanation for this phenomenon may be the reduction of both droplet size and droplets' concentration in the microemulsion as the aqueous phase decreased from 20% to 5%. It has also been shown that a linear correlation exists between the decrease in droplet size and the increase of curcumin loading in the microemulsion. In addition, it has been demonstrated that a micellar system, S/O-mix, and a plain solution of curcumin resulted in a significantly lower curcumin permeation relative to that presented by the microemulsion, Papp=0.018 × 10(-3)± 0.011 × 10(-3), 0.005 × 10(-3)± 0.002 × 10(-3), and 0.002 × 10(-3)± 0.000 × 10(-3)cm/h, respectively, vs. 0.110 × 10(-3)± 0.021 × 10(-3)cm/h for the microemulsion. The enhancement ratio (ER=Jss-ME/Jss-solution) of CUR permeated via 1% loaded microemulsion was 55.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Curcumin, from Curcuma longa (Turmeric), powder
Sigma-Aldrich
Propylene carbonate, anhydrous, 99.7%
Sigma-Aldrich
Curcumin, ≥94% (curcuminoid content), ≥80% (Curcumin)
Supelco
Curcumin, analytical standard
Sigma-Aldrich
Propylene carbonate, ReagentPlus®, 99%
Supelco
Curcumin, matrix substance for MALDI-MS, ≥99.5% (HPLC)
Sigma-Aldrich
Isopropyl palmitate, ≥90%
USP
Curcumin, United States Pharmacopeia (USP) Reference Standard
Supelco
Isopropyl palmitate, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Propylene carbonate, suitable for HPLC, 99.7%
Sigma-Aldrich
Isopropyl palmitate, technical grade, 90%
Curcumin, primary reference standard
Supelco
Propylene carbonate, Selectophore, ≥99.0%
USP
Isopropyl palmitate, United States Pharmacopeia (USP) Reference Standard
Isopropyl hexadecanoate, European Pharmacopoeia (EP) Reference Standard