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Investigating the influences of intermolecular interactions on viscoelastic performance of pressure-sensitive
Jie Liu1, Liang Fang1, Chao Liu1
1Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang, China.
Abstract:
Objective: This study was to clarify the molecular mechanism of viscoelastic performance variations of pressure-sensitive adhesive (PSA) with the addition of drugs by FT-IR spectroscopy and molecular modeling.Significance: Viscoelastic performance of PSA was frequently changed by the addition of drugs in drug-in-adhesive (DIA) patches. It may cause decrease of the physical stability and drug bio-adhesion issues for the development of DIA patch. But, the molecular details of drug-PSA interaction are not clarified.Methods: Model drugs including propranolol (PRO), oxybutynin (OXY), and escitalopram were added into patch with hydroxyl PSA (10%, w/w). Rheological study and thermal analysis were used to characterize the viscoelastic performance and free volume of PSA, respectively. 1H NMR was used to determine the quantity of hydroxyl group in the PSA. FT-IR study and molecular modeling were conducted to describe the types and interaction sites between drug and PSA molecule.Results: The results demonstrated that PRO interacted with -OH and -COOR groups of PSA, which interrupted the interaction between the PSA molecules, resulting in a plasticizing phenomenon of PSA. Escitalopram mainly interacted with -OH of PSA and decreased the rigidity of the drug-loaded PSA only in the high-frequency region. No obvious interaction was found between OXY and PSA, and the viscoelastic performance of PSA did not change significantly.Conclusion: The present study described the molecular mechanism of viscoelastic performance variation, especially the plasticizing effect. These results were essential for the design and development of transdermal patches from the viewpoint of viscoelastic performance.
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