Effect of drug-polymer binary mixtures on the in-vitro release of ibuprofen from transdermal drug-in-adhesive layers.

We report on the formation of eutectic mixtures of ibuprofen using two different polymers together with investigations on the in-vitro release of ibuprofen from drug-in-adhesive layers. Ibuprofen, literature melting point (m.p.) = 73.5-76.5°C, was tested together with Pluronic F127, literature m.p. = 54.4-60.5°C, and polyethylene glycol 1000 (PEG 1000), literature m.p. = 37-40.9°C, as second components in binary mixtures, incorporated into an acrylic adhesive, either as solid physical mixtures (PM) or molten mixtures (MM). Studies of how the type of mixture preparation (PM versus MM) and the ratio of components in binary mixtures affecting the in-vitro drug release of ibuprofen, compared with ibuprofen-adhesive layers without polymer addition were conducted. Ibuprofen release did not improve using the eutectic composition with Pluronic F127, possibly due to increased ibuprofen solubilisation in the adhesive and a subsequent decrease in the thermodynamic activity of the formulation. A significant increase in ibuprofen release (P < 0.05) was shown for compositions adjacent to the eutectic one, with ibuprofen: Pluronic F127 (40:60) and ibuprofen: PEG 1000 (20:80, 25:75, 30:70), from both PM- and MM-adhesive formulations, compared to the ibuprofen-adhesive formulations.