Mixed Solvency Concept to Replace Harmful Organic Solvent: Recent Trends and Future Challenges in Formulation Development

Abstract

Abstract: Organic solvents are hazardous and should be replaced with less harmful alternatives. When developing a new formulation for a medicine with low aqueous solubility, improving its solubility might be a significant difficulty. According to the mixed solvency concept, a novel concept of solubilization, the solubility of poorly soluble drugs can be increased by dissolving them in a concentrated solution comprising various substances. Methods commonly used to improve solubility include complexation, pH modification, salt formation, hydrotropy, cosolvency, and micelle solubilization. By reducing the concentration of specific solubilizers, this method can be used to reduce the toxicity of solubilizers in various formulations of poorly soluble medicines. This review aims to provide scientists with a fresh concept for enhancing medication solubility. The benefits and drawbacks of currently available green solvents have been analyzed as potential replacements for traditional solvents. Some examples of these solvents are bio-based solvents like ethanol, methanol, and cyrene; d-limonene; deep eutectic solvents such as ionic liquids and natural deep eutectic solvents; supercritical fluids; subcritical water; surfactant-based solutions like hydrotopes and supramolecular solvents; and deep eutectic solvents like cyrene.