Abstract—Novel solid lipid nanoparticles (SLNs) were developed to improve oral bioavailability of oxyresveratrol (OXY). The SLNs were prepared by a high speed homogenization technique, at an effective speed and time, using Compritol ® 888 ATO (5% w/w) as the solid lipid. The appropriate weight proportions (0.3% w/w) of OXY affected the physicochemical properties of blank SLNs. The effects of surfactant types on the properties of the formulations such as particle size and entrapment efficacy were also investigated. Conclusively, Tween 80 combined with soy lecithin was the most appropriate surfactant to stabilize OXY-loaded SLNs. The mean particle size of the optimized formulation was 134.40 ± 0.57 nm. In vitro drug release study, the selected S2 formulation showed a retarded release profile for OXY with no initial burst release compared to OXY suspension in the simulated gastrointestinal fluids. Therefore, these SLNs could provide a suitable system to develop for the oral OXY delivery. Keywords—Solid lipid nanoparticles, Physicochemical properties, in vitro drug release, Oxyresveratrol. I. INTRODUCTION XYRESVERATROL (OXY) (Trans-2,4,3’,5’- tetrahydroxystilbene), is a polyphenolic stilbene purified from the heartwood of a Thai traditional plant, Artocarpus lakoocha Roxburgh (Moraceae) [1]. It has been reported to exhibit tyrosinase inhibitory activity, acts as a potent antioxidant, is anti-inflammatory and has strong neuroprotective activity [2]-[5]. Recently, its antiviral activities have been established with activities against several types of herpes simplex virus (HSV-1 and HSV-2), various varicella zoster viruses (VZV), influenza virus as well as human immunodeficiency virus type 1 (HIV-1) [1], [6]-[9]. Y. Sangsen is with the Department of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla 90112 Thailand (e-mail: s.yaowaporn@gmail.com). K. Likhitwitayawuid and B. Sritularak are with the Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330 Thailand (e-mails: Kittisak.L@chula.ac.th, Boonchoo.sr@chula.ac.th, respectively). K. Wiwattanawongsa is with the Department of Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla 90112 Thailand (e-mail: kamonthip.w@psu.ac.th). R. Wiwattanapatapee is with the Department of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla 90112 Thailand (phone: 667-428-8915; fax: 6674 428 148; e-mail: ruedeekorn.w@psu.ac.th). These pharmacological activities have triggered efforts to transform OXY into therapeutic formulations. However, there are some limitations for the oral delivery of OXY such as poor absorption due to intermediate permeability and active efflux mediated mechanisms, extensive hepatic metabolism, and rapid elimination from the body results in a low oral bioavailability and limits the clinical use of OXY [10]-[12]. To overcome these difficulties, it will be necessary to design a formulation for OXY that will improve its oral bioavailability. Lipid-based drug delivery systems, especially solid lipid nanoparticles (SLNs), have been a focus in the last few years for use as alternative colloidal drug carriers. SLNs are produced by replacing the liquid lipid (oil) component of an oil-in-water (O/W) emulsion with lipids that are solid at both room and body temperatures. The systems possess many advantages such as their physical stability, protection of labile drugs from chemical or enzyme degradation, controlled release, biodegradability, and biocompatibility all derived from physiologically accepted excipients that are generally recognized as safe (GRAS) status [13]-[15]. Moreover, many particle synthetic methods can be easily scaled up it to commercial products [16]. Until recently, SLNs have been investigated successfully as oral drug delivery systems for several drugs [17]-[22]. Nonetheless, there have been no reports from investigations using such systems as carriers for the oral delivery of OXY. Predominantly, the proposed mechanisms for the enhanced absorption of SLNs that have been documented involve direct uptake through the intestine, a decreased degradation in the gastrointestinal (GI) tract and reduced hepatic metabolism with a retarded clearance from the body because of its nano-size and the lipid used in the SLNs [23]. Apart from the effect on the stability of the formulations, surfactants also increase the intestinal permeability of SLNs containing a drug by paracellular transport and restraining efflux systems thus increasing transcellular pathways [23]- [25]. Therefore, the preparation processes and composition of such SLN formulations that affect their physicochemical properties as well as their release properties should be investigated to obtain effective SLNs for oral delivery of OXY. The aim of this study was to evaluate the effects of the preparation conditions and formulated ingredients on their appearance, physicochemical characteristics, including Novel Solid Lipid Nanoparticles for Oral Delivery of Oxyresveratrol: Effect of the Formulation Parameters on the Physicochemical Properties and in vitro Release Y. Sangsen, K. Likhitwitayawuid, B. Sritularak, K. Wiwattanawongsa, R. Wiwattanapatapee O World Academy of Science, Engineering and Technology International Journal of Medical Science and Engineering Vol:7 No:12, 2013 873 International Science Index 84, 2013 waset.org/publications/9996796