Abstract
Bar diagram representing thermodynamic parameters obtained for the partitioning of NSAIDs into human erythrocyte ghost membranes at physiological pH; 7.4. [Display omitted]
•Partition coefficients of NSAIDs into HEG membranes were determined.•Thermodynamic parameters were evaluated and successfully analyzed.•Partitioning of NSAIDs into HEG membranes was exothermic.•Partitioning of NSAIDs into HEG is spontaneous with negative free energy values.•Identical partitioning enthalpy–entropy driven compensation mechanism was shown.
In this work,second derivative spectrophotometry was applied for determining the partition coefficients (Kps) of four non-steroidal anti-inflammatory drugs (NSAIDs; flufenamic, meclofenamic, mefenamic and niflumic acids) into human erythrocyte ghost (HEG) membranes over a temperature range from (283.2 to 313.2)K. The proposed method allowed the evaluation and direct analyses of thermodynamic parameters; enthalpy (ΔHW→M), Gibbs energy (ΔGW→M) and entropy (ΔSW→M) changes of the partitioning of NSAIDs into HEG membranes. The partitioning of NSAIDs between polar aqueous phase and non-polar lipid bilayer HEG membrane phase was exothermic with negative (ΔHW→M) which compensated for the changes in (ΔSW→M). The negative values of (ΔGW→M) revealed that the partitioning of NSAIDs into HEG, owing to their transfer from polar aqueous phase and non-polar HEG phase is spontaneous. The enthalpy–entropy correlation analysis resulted in a good linearity that suggests an identical partitioning enthalpy–entropy driven compensation mechanism for the studied NSAIDs.