In this study, solubility, dissolution and permeation processes of poor soluble antiviral anti-SARS-CoV-2 umifenovir (UMF) were improved with sulfobutylether-β-cyclodextrin (SBE-β-CD) solutions and solid dispersion (SD). The low pH dependent equilibrium solubility of UMF at 37 °C was estimated: pH 1.6 (1.91 mM), pH 5.0 (1.98∙10-1 mM), pH 6.5 (2.43∙10-2 mM). The maximal increase of 66.7-fold was detected with SBE-β-CD in buffer pH 6.5 solution. The amounts of 0.22 % (UMF pure) and 11.54 % (UMF/SBE-β-CD_SD) of a dose were dissolved within 7 h in buffer pH 6.5 medium, whereas in pH 1.6 the whole dose was released from UMF/SBE-β-CD_SD. Screening of biocompatible polymers to improve the UMF/SBE-β-CD_SD dissolution and permeation in pH 6.5 showed the best potential of PEG 1000 (10 %). The most efficient systems were studied in biorelevant media. Findings of the study demonstrated the importance of disclosing the UMF solubility, dissolution and permeation under physiologically relevant conditions in order to gain insights into their performance after oral administration.
