Background::Hot-melt Pressure-sensitive Adhesives (HMPSA) are eco-friendly pressuresensitive
adhesives, with the potential of being used as substrates for transdermal patches. However,
due to the low hydrophilicity of HMPSA, the application is limited in the field of Traditional Chinese
Medicine (TCM) plasters.
Methods::Three modified HMPSA were prepared with acrylic resin EPO, acrylic resin RL100, and
Polyvinylpyrrolidone (PVP) as the modifying materials. The physical compatibility between HMPSA
and the modifying materials was investigated through in vitro release performance, viscosity, softening
point, cohesion, and fluidity, so as to determine the most effective modifying material. The impact
of the modified HMPSA on the release properties of different TCM ingredients was elucidated
by the performance of water absorption and contact angle behavior.
Results::With the addition of the modifying materials, both the viscosity and the softening point of
HMPSA were improved, with the flowability reduced and the cohesion maintained. The morphological
and structural changes reflected the physical compatibility between HMPSA and the three modifying
materials. According to the results of in vitro release experiments, PVP effectively improved
the release performance of paeoniflorin, ephedrine hydrochloride, and cinnamaldehyde in HMPSA,
with no significant impact on the release performance of eugenol. The changes in the drug release
performance of HMPSA may be attributed to the improved hydrophilicity of HMPSA after physical
modification.
Conclusion::The compatibility and the drug release performance of HMPSA were effectively enhanced
after the addition of the modifying materials by the physical blending technique. Among the
three modifying materials, PVP has been found to be an ideal modifying material for HMPSA in the
field of TCM plasters due to its effects on drug release performance.