Abstract 5709: Formulation development and evaluation of nanostructured lipid carriers for topical delivery of honokiol

Purpose: Honokiol, a plant lignan isolated and purified from Magonila Officinalis has been shown to have chemopreventive effects in chemically induced and UV-B induced skin tumor development in SKH-1 mice. However poor solubility of honokiol greatly limits its clinical application. The key objectives of the present investigation are to improve the solubility and stability of honokiol by encapsulating in nanostructured lipid nanoparticles. Methods: Honokiol was incorporated into nanostructured lipid nanoparticles and cream using hot homogenization method. Compritol 888 ATO, Precirol ATO 5, and miglyol 812 as lipid matrices and poloxamer 188 as emulsifier. Lipid nanoparticles were characterized for size, zeta potential, shape and morphology using photon correlation spectroscopy (PCS) and atomic force microscopy (AFM). Honokiol was quantified by isocratic HPLC method using mobile phase of 60:40 (%v/v, acetonitrile:water) at a flow rate of 1 ml/min at a wavelength of 254 nm. Permeation studies were carried out using porcine dermatome skin in Franz diffusion cell. Honokiol concentration corresponding to 0.5 mg/ml in sesame oil, cream and lipid nanoparticles was dispersed in PBS pH 7.4. Permeation studies were performed till 24hrs; the samples (200 µl) were withdrawn at regular time intervals and replaced with fresh medium. Amount of honokiol permeated across porcine skin was quantified using HPLC method. Stability of cream and lipid nanoparticle formulations was studied at 30° C and 65 % relative humidity in a stability chamber for one month. Results: The size of the optimized honokiol loaded lipid nanoparticles was 145±7 nm with a polydispersity index of 0.24±0.02. The zeta potential and encapsulation efficiency was 0.34±0.02 mV and 97±2 %. The particle size of lipid nanoparticles measured in AFM was very close to size measured by PCS. In case of precirol cream, particle size was more than 20 µm with drug content of 89±5 %. Honokiol loaded nanostructured lipid nanoparticles, and cream were stable for about 30 days without any significant changes in particle size, and drug content at 30° C and 65 % relative humidity. Skin treated with honokiol entrapped in nanoparticles and cream has shown more retention of honokiol in the skin compared to plain honokiol in sesame oil. Proposed lipid cream and nanoparticles formulation has shown effective skin penetration of honkiol. From the data it is evident that nanoparticles has shown higher amount of honokiol in skin compared to cream formulation. Conclusions: Preliminary results of this study have shown the potential of lipid based formulations for topical delivery of honokiol. Chemopreventive potential and efficacy of honokiol encapsulated in lipid based formulations will be evaluated in UV-B induced skin cancer model. Acknowledgements: Supported by Translational Cancer Research Center funded by the South Dakota Governor9s Office of Economic Development. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5709. doi:1538-7445.AM2012-5709