Transdermal delivery of cyclodextrin-solubilized curcumin

The purpose of the present investigation was to explore the effect of cyclodextrin (CD) as permeation enhancer through rat skin in the form of a valuable and stable transdermal drug delivery system by exploiting its favorable properties. Phase-solubility studies demonstrated that the CD:drug ratio 1:2 was employed in complexation. Solid-state characterizations of complexes was performed by differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared, nuclear magnetic resonance spectrophotometry analysis, and scanning electron micrograph. The HP-β-CD by virtue of its greater stability than the pure curcumin (CMN), allowed greater transdermal flux of CMN indicative of enhanced permeation via CMN-2-hydroxy propyl β cyclodextrins (HP-β-CD). Permeability studies of drug, complex, and with various penetration enhancers (PEs), were performed through rat skin, highlighted a favorable effect of CDs on drug permeation rate, due to its solubilizing action; in contrast with unpredictably poor skin permeation of pure drug. The complexes were found to cause relatively less irritation as compared to the pure drug and drug with PEs in skin irritation studies. The anti-inflammatory activity using paw odema model showed that the formulations of CMNCur–HP-β-CD complex exhibited significant (p < 0.001) decrease in paw edema volume than its pure CMN gel demonstrating enhanced biological activity.