http://informahealthcare.com/phd ISSN: 1083-7450 (print), 1097-9867 (electronic) Pharm Dev Technol, Early Online: 1–9 ! 2015 Informa Healthcare USA, Inc. DOI: 10.3109/10837450.2015.1022789 RESEARCH ARTICLE Physicochemical characterization of emulgel formulated with SepineoP 600, SepineoSE 68 and cosolvent mixtures Enam A. Khalil 1 , Samia A. Majid 2 , Ghadeer A. R. Y. Suaifan 3 , Faisal T. Al-Akayleh 4 , and Al-Sayed A. Sallam 5 1 Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, The University of Jordan, Amman, Jordan, 2 Faculty of Pharmacy, The University of Jordan, Amman, Jordan, 3 Department of Pharmaceutical Sciences, Faculty of Pharmacy, The University of Jordan, Amman, Jordan, 4 Faculty of Pharmacy, Petra University, Amman, Jordan, and 5 TQ Pharma, Amman, Jordan Abstract The combined properties of SepineoP 600 (S600), a self-gelling dispersion and SepineoSE 68 (M68), a natural liquid crystal forming surfactant, were utilized in the development of emulgel base for topical application. The emulgels were prepared in water alone or combined with propylene glycol (PG), polyethylene glycol 400 (PEG400) and glycerol (G) as cosolvents. Emulgels were characterized for their optical and flow behavior. Two model drugs: caffeine (CF) and methylparaben (MP) were used in the evaluation of drug permeation across the stratum corneum (SC). The results showed that emulgel prepared using 70% PG:water (1:1) and 30% S600 has the best flow behavior compared to other cosolvents. Also the permeability coefficient of CF was found to be higher than that of MP and the addition of 3% M68 improved the physical stability of the emulgel, but it did not affect the drug diffusion profile. Keywords Emulgel, phase behavior, rheology, SepineoP 600, SepineoSE 68, stratum corneum History Received 14 December 2014 Revised 4 February 2015 Accepted 11 February 2015 Published online 11 March 2015 Introduction As a valuable class of pharmaceutical preparations, gels that consist of organic polymers of natural or synthetic origin are usually formed by entrapment of large amounts of aqueous or hydroalcoholic liquid in a network of colloidal solid particles 1 . Fortunately, the presence of such large aqueous environment permits easy migration of drugs and therefore enhances drug dissolution. Numerous advantages of gels have been reported, such as being thixotropic, compatible with several excipients and water-soluble or miscible materials 2 . However, their major drawback lies in their inability to carry hydrophobic drugs. This was resolved by combining gels and emulsions in a dosage form referred as emulgels. Recently, there has been great interest in the use of novel polymers with complex functions as emulsifiers and thickeners because their gelling capacity allows the formulation of stable emulsions. Such stability was correlated to the decrease in surface and interfacial tension and at the same time to the increase in the viscosity of the aqueous phase 3,4 . A good example of the aforementioned novel polymers is SepineoP 600 (Simulgel 600 or S600) which forms emulgels characterized by several favorable properties, transparent and have the ability to accommodate both hydrophilic and hydrophobic dugs 4,5 . S600 is a concentrated droplet dispersion of acrylamide/ sodium acryloyldimethyltaurate, which usually forms a viscous liquid at room temperature, in isohexadecane as the oily dispersing phase containing polysorbate 80 as the stabilizer. When water is added, it interacts instantly with the polymer forming a semisolid network. S600 is capable of thickening several solvent-rich media which include ethanol, acetone, glycerin and other glycols. The consistency and the extent of interaction in gel formulations can be assessed using the results of the rheology measurements in both steady state and oscillation modes. Bonacucina and co-workers investigated S600 gels at a concentration range between 0.5% and 5% (w/w). The gels were characterized by oscillation rheology and the results of their investigation revealed that the dynamic moduli were very dependent on polymer concentration. The 3–5% (w/w) concen- tration systems showed typical gel-like behavior whereby the structure of the formed gel was characterized by weak polymer– polymer interactions. Hence, such characteristic is advantageous for topical administration 6 . In the steady state measurements, the yield stress was reported as a good indicator for the strength of the cohesive energy in gel structure 7 . SepineoSE 68 (Montanov68 or M68) is a non-ionic glucoli- pidic surfactant containing cetyl and stearyl alcohol with cetearyl glucoside. M68 can be used to formulate smooth textures with any type of oil phase and to modulate textures and flexibility of emulsion as desired. M68 can also promote liquid crystals formation that act as water reservoir within emulsions. As an emulsifier, M68 is very stable and can emulsify extremely acidic or basic media without degradation 8 . Vuc ˇinic ´-Milankovic ´ and co-workers investigated two sugar- based emulsifiers, cetearyl alcohol-cetearyl glycoside and sorb- itan stearate–sucrose cocoate, in order to formulate an optimal vehicle for amphiphilic drug, such as diclofenac diethylamine. These emulsifiers are known as potential promoters of lamellar liquid crystals/gel phases. Rheological behavior and droplets size distribution indicated satisfying physical stability of both types of Address for correspondence: Prof. Dr Enam A. Khalil, Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, The University of Jordan, Amman 11942, Jordan. Tel: +962 6 5355000x23325. Fax: +962 6 5300250. E-mail: ekayoub@ju.edu.jo Pharmaceutical Development and Technology Downloaded from informahealthcare.com by University of Jordan on 03/11/15 For personal use only.