Interaction
of an Amphiphilic Drug Trifluoperazine
Dihydrochloride with Pluronic Triblock Copolymers: A Physicochemical
Study
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Abstract
In
the present study, we report the interactional behavior of the
phenothiazine drug trifluoperazine dihydrochloride (TFP) with Pluronics
(L64, F68, and P123) using surface tension, cloud point and fluorescence
measurements. Various micellar and interfacial parameters such as
critical micellization concentration (cmc), interaction parameter
(β), effectiveness of surface tension reduction (π<sub>cmc</sub>), maximum surface excess concentration (Γ<sub>max</sub>), and minimum area per molecule (<i>A</i><sub>min</sub>) at the air–water interface have been evaluated using surface
tension technique. The phase separation behavior of the drug is studied
in the presence of Pluronics, and the corresponding thermodynamic
parameters such as Gibbs free energy (Δ<i>G</i>°<sub>c</sub>), standard enthalpy (Δ<i>H</i>°<sub>c</sub>), and entropy (<i>T</i>Δ<i>S</i>°<sub>c</sub>) of clouding have been calculated. Employing the
steady state fluorescence measurements, the interactions between the
drug and Pluronics have been determined in terms of the number of
binding sites for drug molecules (<i>n</i>), binding constants
(<i>K</i><sub>a</sub>), and Stern–Volmer quenching
constants (<i>K</i><sub>sv</sub>)