Solubilization of Carbamazepin by Different Classes of Nonionic Surfactants and a Bile Salt

Solubilization of carbamazepin, a slightly soluble antiepileptic drug is investigated in representative classes of eight nonionic surfactants, viz., Tweens 20, 40, 60 & 80; Myrjs 51 & 52; and Brijs 35 & 98. The solubility of carbamazepin in acueous solutions of these detergents was determined over the concentration range of 0-0.09 mole/liter at 37°. A marked increase in solubility is noticed with all the surfactants used. Dihydroxy bile salts such as sodium deoxycholate have many detergent-like properties derived from their unusual amphiphilic structure. The solubility of carbamazepin in sodium deoxycholate was determined over the concentration range of 0-0.2 mole/liter at 37°. Increasing the concentration of the bile salt, increased the solubilized amount of carbamazepin. Comparison with solubilisation in typical micelle-forming systems indicates that the self-association of the bile salt is very complex and exhibit a very different pattern. Further examination of the solubilization data in terms of the mutual association of carbamazepin with aggregate species shows that the self-association of sodium deoxycholate is consistent with a model that includes the formation of dimers, pentamers, and large aggregates.