Thermodynamics of partitioning of some sulfonamides in 1‐octanol–buffer and liposome systems

Abstract

The thermodynamics of partitioning of some structurally related sulfonamides have been determined in 1‐octanol–aqueous buffer and liposome systems. The partition coefficients were approximately tenfold higher in liposomes compared with 1‐octanol. The enthalpies of transfer from aqueous media to organic systems were positive in liposomes but negative or positive in 1‐octanol, whereas the entropies of transfer were positive in almost all cases. Copyright © 2002 John Wiley & Sons, Ltd.

Thermodynamics of partitioning and solvation of ketoprofen in some organic solvent: buffer and liposome systems

“…Temperature-dependence of the rational partition coefficients for the KTP in all tested partitioning systems is summarized in Table II (Martínez, Gómez, 2002;Ávila, Martínez, 2003). Found data are in agreement that this drug displays a semi-polar and lipophilic behavior.…”

“…As it was mentioned previously, a method widely used in the physicochemical study of pharmaceutical compounds (such as drugs) is by means of the analysis of the temperature-dependence for partitioning by using the van't Hoff method. This procedure permits obtain the standard enthalpy change (ΔH represent the standard changes in enthalpy and entropy, respectively, when one mole of drug is transferred from the aqueous medium to the organic system at infinite dilution expressed in the mole fraction scale (Betageri et al, 1996;Martínez, Gómez, 2002).…”

“…All aliquots were weighted in a digital analytical balance (Mettler AE 160, Germany) whose sensitivity was ± 0.1 mg. Mixtures were then stirred on a mechanical shaker (Wrist Action Burrel model 75, USA) for one hour. Samples were placed on water baths (Magni Whirl Blue M. Electric Company, USA) at 20.0, 25.0, 30.0, 35.0, 40.0, and 45.0 °C (± 0.1 °C) at least for 48 hours with sporadic stirring in order to achieve the partitioning equilibrium, as it was made studying other compounds (Martínez, Gómez, 2002). After this time-period, the aqueous phase was removed followed by determining the drug concentration by means of UV absorbance measurement and interpolation on a previously constructed calibration curve for KTP in a buffer pH 7.4 (Unicam UV2-100 spectrophotometer, USA for CHL-saturated buffer (Dallos, Liszi, 1995;Baena et al, 2005;Mora et al, 2005).…”

“…Liposomes were prepared by a modified Bangham method (1993) as it was made studying other compounds (Betageri et al, 1996;Martínez, Gómez, 2002). Thin films of 40 mg of DMPC or DPPC were formed on the walls of 50 mL round-bottomed flasks after rotary evaporation (Buchler Instr.)…”

“…This has been found especially in the case of some phenols (Rogers, Davis, 1980;Anderson et al, 1983), phenotiazines (Ahmed et al, 1981(Ahmed et al, , 1985, beta-blockers (Betageri, Rogers, 1987), and non-steroidal antiinflammatory drugs (Betageri et al, 1996). In addition, dipyridamole partitioning was higher in liposomes than in octanol (Betageri, Dipali, 1993), as well as for mefloquine, quinine, and other antimalarial drugs (Go et al, 1995(Go et al, , 1997, also for some sulfonamides (Martínez, Gómez, 2002), and benzocaine (Avila, Martínez, 2003). For these reasons, different liposome types have been used combined to organic solvents for partitioning experiments in order to develop quantitative structure-activity relationships (QSAR studies).…”