Solubilization of Clonazepam, Diazepam and Lamotrigine Using Ethanol and Sodium Dodecyl Sulfate

Abstract

The apparent solubilities of clonazepam, diazepam and lamotrigine in binary mixtures of ethanol + water at 298.2 K in the presence of three different concentrations of sodium dodecyl sulfate (SDS) are reported. Using this approach, 2250, 7733, and 153 times enhancement in the aqueous solubility of clonazepam, diazepam, and lamotrigine were achieved, respectively. Melting point and polar surface area were determined as indicators of solubility enhancement by SDS and ethanol, respectively. The Jouyban-Acree model was used for correlating the reported data and the obtained mean relative deviations are 7.2, 10.0 and 7.9 %, respectively. When all data points of clonazepam, diazepam and lamotrigine in binary solvents at various SDS concentrations were fitted to the model, the mean relative deviations are 10.0, 17.3, and 11.8 %, respectively. The results reveal that the model could be used for mathematical representation of cosolvent and surfactant concentrations on the solubility of these pharmaceuticals. This study shows that for aqueous solutions SDS is a solubility enhancer in the presence of organic solvents and this could be helpful in reducing the need for organic solvents in pharmaceutical dosage forms where avoidance of higher concentrations of organic solvents is desirable.