Abstract
In order to examine the dispersibility of sulfisoxazole, sulfadimethoxine, and N1-acetyl-sulfisoxazole in aqueous sodium lauryl sulfate (SLS)-sucrose solutions, the apparent median redius (γmed) obtained from the particle size distribution as determined by the sedimentation balance and sedimentation volume were measured at sucrose concentrations of 0-30% and SLS concentrations of 1- 8×10-3 mole/liter, and the effect of SLS and sucrose on the dispersibility of those sulfonamides was investigated. It was thereby recognized that both γmed and sedimentation volume markedly decreased until the SLS concentration reachec 4×10<-3> mole/liter, beyond which they were almost constant. This SLS concentration was the same as that at the maximum point of ζ-potential. From these results, it was concluded that the dispersive sedimentation begins at the SLS concentration of 4×10-3 mole/liter, and that the addition of sucrose has no effect on this concentration. Correlation of dispersibility with the amount of SLS adsorbed on the sulfonamides was examined. It was found that the adsorbed amount of SLS required for dispersive sedimentation of the three sulfonamides was 47, 51, and 50% of the saturated amount adsorbed, respectively.
