Co-Crystallization as a Strategy for Solubility Enhancement: Design, Development, and Pharmaceutical Applications

<p><span>Limited water solubility poses a major challenge to the oral bioavailability of many active pharmaceutical ingredients (APIs), particularly those categorized as BCS Class II and IV drugs. Traditional approaches to enhance solubility, such as micronization, solid dispersion, and salt formation, have limitations, especially for compounds that cannot be ionized. Pharmaceutical co-crystals offer a promising alternative by modifying the crystal lattice through non-covalent interactions between the API and a pharmaceutically acceptable co-former, without altering the drug's pharmacological properties. This approach can enhance the solubility, dissolution rate, bioavailability, stability, mechanical strength, and manufacturability of drugs. Co-formers are generally selected from the GRAS list to ensure safety, and co-crystals can be produced using various methods, including grinding, solvent evaporation, hot-melt extrusion, anti-solvent addition, and spray drying. Research has demonstrated the successful use of co-crystals in improving physicochemical properties and enabling controlled release or taste masking. Several co-crystal-based formulations have been commercialized, underscoring their clinical and market importance. With advancements in co-former screening and regulatory acceptance, co-crystals are expected to play a vital role in overcoming formulation challenges in modern drug development</span><span>.</span></p>