Mixed micelles of structurally related antidepressant drugs

 The composition of micelles in a binary mixture of the amphiphilic antidepressant drugs imipramine hydrochloride and clomipramine hydrochloride has been determined from an analysis of the variation of the critical micelle concentration from conductivity techniques as a function of solution composition. The equilibrium distribution of components between micelle and monomer phases was evaluated using a theoretical treatment based on excess thermo-dynamic quantities. The nonideality of mixing, expressed in terms of the interaction parameter β, was appreciable in systems containing low imipramine mole fractions, suggesting differences in the packing characteristics within micelles of these two drugs. Received: 7 July 1997 Accepted: 10 August 1997