Sulphonamides, solubilization

The behaviour of sulphisoxazole in surfactant and glycol solutions has been studied in a series of papers [140,141]. In order to clarify the mechanism of the reduction in rectal absorption of this sulphonamide in the presence of PEG 4000 the effect of this compound on its physicochemical properties was examined. There is a linear relationship between the solubilities of sulphathiazole, sulphapyridine, and sulphisoxazole and the concentration of PEG 4000. The drugs apparently do not form complexes with the glycols it is thought that the reduction in activity is due to a depression of the concentration of the drug in rectal lipid. The effect of non-ionic surfactants is to reduce the absorption of the sulphonamides through solubilization in micelles [141]. Fig. 6.18 indicates the extent of solubilization in polysorbate 80 solutions. Values of apparent distri-... 

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