Physical-chemical and thermal studies of solid dispersions of desloratadine

Background. Currently, various approaches can be used to increase the solubility and dissolution rate of poorly water-soluble pharmaceutical substances, such as salt formation, solubilization with co-solvents, particle size reduction, or preparation of solid dispersions. A promising and relevant area in pharmaceutical science is the production of solid dispersions. Polyvinylpyrrolidone and polyethyleneglycols of various molecular weights are most often used as carrier polymers in the production of solid dispersions.

Aim. Analysis of desloratadine solid dispersions by physicochemical and thermal methods in order to substantiate the most optimal composition and technology for obtaining solid dispersions.

Materials and methods. Solid dispersions of desloratadine with polyethyleneglycol-1500, polyethyleneglycol-4000, polyethyleneglycol-6000, polyvinylpyrrolidone-10000 as carriers in the ratios of 1:1, 1:2, 1:5 were used as objects of study. To determine the morphological features of the obtained samples, scanning electron microscopy was used on a JSM-6380LV device (JEOL, Japan). IR spectroscopy was performed on a Vertex-70 device (Bruker Optik GmbH, Germany), in the mid-IR region of 4000–400 cm^–1 using the total internal reflection method. In order to study the crystal structure of solid dispersions with polymer carriers, X-ray phase analysis was performed using the powder X-ray diffractometry method on a DRON device. Studies by the differential scanning calorimetry (DSC) method were carried out on a synchronous thermal analysis device model STA 449 F3 (Netzsch, Germany).

Results. IR spectra of desloratadine solid dispersions demonstrated fluctuations in the areas corresponding to the functional groups of the pharmaceutical substance and polymers. The X-ray diffraction pattern of samples of desloratadine solid dispersions with polymers shows a loss of the crystalline structure of the pharmaceutical substance. when conducting differential scanning calorimetry, the lowest value of specific heat of complexation was found for solid dispersions of desloratadine with polyethyleneglycol –1500 and polyethyleneglycol –6000.

Conclusion. The conducted studies showed that the optimal polymer for obtaining solid dispersions is polyethyleneglycol-1500.