Mixed micelles of the antihistaminic cationic drug diphenhydramine hydrochloride with anionic and non-ionic surfactants show improved solubility, drug release and cytotoxicity of ethenzamide

Abstract

This study aimed to apply mixed drug–surfactant micelles to enhance the solubility and reduce the cytotoxicity of poorly water-soluble active pharmaceuticals. Nanosized drug–surfactant formulations were prepared using antihistaminic cationic drug diphenhydramine hydrochloride (DCP) with anionic sodium deoxycholate (SDC) and non-ionic transglycosylated stevia (Stevia-G) surfactants. Surface tension and fluorescence methods were used to evaluate mixed micellization in an aqueous medium. The negative interaction parameters (βm) values of the drug-surfactant mixed micelle showed the strong attractive interactions of DCP with SDC and Stevia-G. The applicability of the drug-surfactant mixed micelle for enhancing the binding constant (logKb), partition coefficient (logKm) and molar solubilization ration (MSR) of the non-steroidal anti-inflammatory drug, ethenzamide (ETZ) was evaluated. The %EE of ETZ in DCP at αDCP = 1.0 was higher than that of SDC and Stevia-G, reflecting the formation of a hydrogen bond between ETZ and DCP. The controlled released of ETZ in PBS at pH 7.4 was approximately 10% from both mixed micelles after 55 h. In addition, cell viabilities in the presence of ETZ and SDC were reduced to 48% and 40% at 0.5 and 3.0 mM, respectively, indicating their high cytotoxicity. By contrast, cell viability was >90% in the presence of mixed micelles of DCP–SDC and DCP–Stevia-G with αDCP = 0.9 at 3.0 mM, suggesting low cytotoxicity. These data show that nanosized mixed micelles facilitate the passage of these two drugs through the cell membranes, thereby leading to their improved uptake into the target cells.