Thermodynamic functions relative to the transfer of ketoprofen from water to some organic systems.

The thermodynamics of molal partitioning of ketoprofen (KTP) was studied in cyclohexane/buffer (CH/W), octanol/buffer (ROH/W), and dimyristoyl phosphatidylcholine (DMPC), dipalmitoyl phosphatidy1choline (DPPC), and egg lecithin (EGG/W) liposome systems. In all cases the partition coefficients (K-ow(m)) were greater than unity; therefore the standard free energies of transfer were negative indicating affinity of KTP for organic media. The K-ow(m) values were approximately seventy-fold higher in the ROH/W system compared with the CH/W system. On the other hand, the K-ow(m) values were approximately ten or fifty-fold higher in the liposomes compared with the ROH/W system. In all cases, the standard enthalpies and entropies of transfer of KTP were positive indicating some degree of participation of the hydrophobic hydration on partitioning processes.