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Abstract:The majority of drugs have a low dissolution rate, which is a limiting step for their absorption. In this manuscript, solid dispersions (SD), solid self-microemulsifying drug delivery systems (S-SMEDDS) and solid self-nanoemulsifying drug delivery systems (S-SNEDDS) were evaluated as potential formulation strategies to increase the dissolution rate of carbamazepine. Influence of increased dissolution rate on permeability of carbamazepine was evaluated using PAMPA test. In S-SMEDDS and S-SNEDDS formulations, the ratio of liquid SMEDDS/SNEDDS and solid carrier (Neusilin ® UFL2) was varied, and carbamazepine content was constant. In SD formulations, the ratio of carbamazepine and Neusilin ® UFL2, was varied. Formulations that showed the best dissolution rate of carbamazepine (SD_1:6, SMEDDS_1:1, SNEDDS_1:6) were mutually compared, characterization of these formulations was performed by DSC, PXRD and FT-IR analyses, and a PAMPA test was done. All formulations have shown a significant increase in dissolution rate compared to pure carbamazepine and immediate-release carbamazepine tablets. Formulation S-SMEDDS_1:1 showed the fastest release rate and permeability of carbamazepine. DSC, PXRD and FT-IR analyses confirmed that in S-SMEDDS and S-SNEDDS carbamazepine remained in polymorph form III, and that it was converted to an amorphous state in SD formulations. All formulations showed increased permeability of carbamazepine, compared to pure carbamazepine.

The preparation and characterization of films and nanofibers with carvedilol as a poorly water-soluble drug in poly (ethylene oxide) (PEO) polymer were investigated. Films are prepared by solution casting method, and nanofibers by electrospinning from a polymer solution. Water and mixture of ethanol and water were used as solvents. FT-IR analysis of the samples showed that there was no interaction between the polymer and the drug substance. DSC analysis revealed that carvedilol was dissolved in the polymer and influenced the degree of crystallinity of PEO. Carvedilol release rate for all of the formulations was increased in comparison with pure carvedilol. Significant differences in the rate of release of carvedilol from the films and nanofibers were observed. Field Emission Scanning Electron Microscope (FESEM) images of the obtained fiber was revealed the dependence of the fiber diameter of formulation and electrospinning process parameters, and consequently influence the amount and distribution of carvedilol in the encapsulated fibers.

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. [Projekat Ministarstva nauke Republike Srbije, br. TR 34007]