Solid Dispersion of Usnic acid–HPMC 2910 Prepared by Spray drying and Freeze drying Techniques

• Published in: Oriental journal of chemistry 2018-01, Vol.34 (4), p.2083-2088
• Main Authors: Fitriani, Lili, Afriyanti, Irma, Afriyani, Afriyani, Ismed, Friardi, Zaini, Erizal
• Format: Article
• Language: English
• Subjects: Acids; Dispersions; Fourier transforms; Freeze drying; Functional groups; Higher education; Infrared spectroscopy; Leaves; Lichens; Melting points; Morphology; Pharmacology; Scanning electron microscopy; Solubility; Spectrum analysis; Spray drying; Thermodynamic properties; X ray powder diffraction; X ray spectra; X-ray diffraction
• ISSN: 0970-020X; 2231-5039
• DOI: 10.13005/ojc/3404048

Usnic acid is a dibenzofuran derivate produced by some lichens species primarily Usnea sp., that has several pharmacological activities. Based on Biopharmaceutical Classification System (BCS), usnic acid belongs to class II that has high permeability but low solubility. Therefore, the purpose of this research was to increase the solubility of usnic acid by preparing solid dispersions (SD) using hydrophilic polymer HPMC 2910. Usnic acid and HPMC at ratio 1:1 (w/w) were prepared for solid dispersion using spray drying and freeze drying techniques. Physical mixture at the same ratio was prepared as comparison. Characterization for intact materials, physical mixture and solid dispersions were done using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), fourier transform infra-red (FT IR) spectroscopy, and solubility test. The result of PXRD showed a decrease of peak intensity for solid dispersions. Thermal properties of solid dispersions showed lower melting point compared to usnic acid and physical mixture. The morphology of solid dispersion depicted different shape compared to intact materials and physical mixture. The infra-red spectrum showed the slightly shift at wave numbers of functional groups but there was no new functional groups formed. The solubility of solid dispersions significantly increased, which the solubility test result were 55±0.023, 227±0.034, 567± 0.020, and 932±0.053 (μg/ml) for intact usnic acid, physical mixture, SD by spray drying and SD by freeze drying, respectively. In conclusion, solid dispersions of usnic acid – HPMC 2910 were able to modify physicochemical properties and increased the solubility.