Abstract
Taking into account the advantages of surfactant micelles as drugs carriers, the solubilization of two model drugs, sulfamethoxazole and metronidazole, has been studied in aqueous solutions of benzalkonium chloride, which is a cationic surfactant safe for human use. The combination of conductivity and 1H NMR experiments led to the conclusion that the less soluble drug, sulfamethoxazole, was solubilized in the interior of the surfactant micelles. In the case of metronidazole the 1H NMR results showed that it interacted to some extent with the polar headgroup of the surfactant. However, this interaction was weak since no change in the micellization phenomenon was observed, at least under the experimental conditions used.