Application of mixture experimental design in formulation and characterization of solid self-nanoemulsifying drug delivery systems containing carbamazepine

Abstract

One of the problems with orally used drugs is their poor solubility, which can be overcame by creating solid self-nanoemulsifying drug delivery systems (SNEDDS). Aim is choosing appropriate SNEDDS using mixture design and adsorption of SNEDDS on a solid carrier to improve the dissolution rate of carbamazepine. Self-emulsifying drug delivery systems (SEDDS) consisting of oil phase (caprilic-capric triglycerides), a surfactant (Polisorbat 80 and Labrasol? (1:1)) and cosurfactant (Transcutol? HP) are formed by applying mixture design. 16 formulations were formulated, where proportion of lipids, surfactant and cosurfactant were varied (input parameters) in the following ranges: 10-30%, 40-60%, 30-50%, respectively. After dilution of SEDDS with water (90% water), the droplet size and polydispersity index (PdI) of the obtained emulsions (output parameters) were measured using photon correlation spectroscopy. After processing data, appropriate mathematical models that describe the dependence of input and output parameters were selected. The optimized SNEDDS was adsorbed on the carbamazepine and solid carrier physical mixture, containing 20% carbamazepine. Neusilin? UFl2, Neusilin? FL2, Sylysia? 320, diatomite were used as the carriers. The ratio of SNEDDS:carrier varied (1:1, 2:1). Dissolution testing was carried out in the rotation paddles apparatus. Caracterization of solid SNEDDS was performed using the hot stage microscopy (HSM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectrophotometry with Fourier transformation (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (PXRD). Selected SNEDDS consisting of lipids (21.12%), surfactant (42.24%) and cosurfactant (36.64%) had a droplet size 157.02?34.09 nm and PDI 0.184?0.021. Drug release profiles showed that in all formulations dissolution rate increased (the fastest drug release was observed in formulations with Sylysia? 320). It can be concluded that in all formulations carbamazepine is present in the thermodynamically most stable polymorphic form III. Formulation of solid SNEDDS can significantly increase dissolution rate carbamazepine, with conservation of the polymorphic form III CBZ and potentially increased bioavailability.