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Updated: Aug 9, 2025

Solubility of Hydrophobic Compounds in Aqueous Solution Using Combinations of Self-assembling Peptide and Amino Acid
Published on: September 20, 2017
The challenge of improving pterostilbene (PTS) solubility for solid and semi-solid dosage forms: The obtention of
Mairique Waszczuk1, Sara Elis Bianchi1, Vanessa Pittol1
1Programa de Pós Graduação em Ciências Farmacêuticas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
Abstract:
Pterostilbene (PTS) is a drug candidate with low water solubility and poor bioavailability. On the other hand, drug:cyclodextrins complexes frequently provide bulk powders with low drug concentrations, which is crucial for obtention solid or semi-solid pharmaceutical dosage forms. In order to determine the optimal conditions for enhancing the solubility of PTS:BCD (β-cyclodextrin) complex, a Box-Behnken design was performed. Although the optimal conditions have been applied, low complexation efficiency (0.127) and the bulk powder remained. A PTS:BCD:HPMC (HPMC, hydroxypropyl methylcellulose) ternary system was developed to overcome this limitation, comparing two media, water and a mixture of ethanol-water. When ethanol was used as a co-solvent, the PTS:BCD:HPMC ternary system (freeze-dried) contained 116.65 ± 1.40 mg/g of PTS. This value was 3.4-fold higher than the PTS content observed when the same ternary system was obtained in aqueous media (34.8 mg/g) and 2.8-fold higher than the PTS content observed for PTS:BCD complex (freeze-dried) obtained using ethanol as a co-solvent. Dissolution tests revealed that after 120 min, in a buffer with a pH value of 1.2, only 43% of PTS dissolved. In contrast, 80% and 90% of PTS were dissolved from the PTS:BCD complex and PTS:BCD:HPMC ternary system, respectively. Moreover, the dissolution was fast in a buffer with a pH value of 6.8. PTS:BCD complex reached the maximum PTS dissolution at 75 min and PTS:BCD:HPMC at 45 min. In summary, the results of this study demonstrated, for the first time, that low-bulk powders with a high content of PTS can be obtained from PTS:BCD:HPMC ternary systems using ethanol as a co-solvent. This new finding offers a valuable alternative for producing solid or semi-solid formulations containing highly soluble PTS.
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