Development and Evaluation of Fluconazole Co-Crystal for Improved Solubility and Mechanical Properties

<b>Background</b>: Fluconazole (FLZ) is a broad-spectrum anti-fungal drug presenting poor flowability, mechanical properties, and limited aqueous solubility. These issues pose challenges for the handling and manufacturing of dosage forms of FLZ. The current research aimed to develop fluconazole co-crystal (CC) for improving its aqueous solubility, flowability, and mechanical properties. (2) <b>Methods:</b> The fluconazole benzoic acid (FLZ-BA) co-crystal was prepared using the solvent evaporation technique. The prepared co-crystal was characterized for drug content, solubility, anti-fungal activity, dissolution, and stability. DSC (Differential Scanning Calorimetry), PXRD (Powder X-Ray Diffraction), SEM (Scanning Electron Microscopy), and FTIR (Fourier Transmission Infrared) spectroscopy were carried out to confirm the co-crystal formation. The co-crystal was further evaluated for their flow characteristics and mechanical properties via CTC (compressibility, tabletability, and compactibility), Heckel, and Kawakita analysis. (3) <b>Results</b>: The CC showed 69.51% drug content and 13-fold greater aqueous solubility than pure FLZ. The DSC thermogram showed a sharp endothermic peak between the parent components, a distinct PXRD pattern was observed, and the SEM analysis revealed a different morphology, confirming the formation of co-crystal (new crystalline form). The CC showed immediate drug release and was found to more stable, and less hygroscopic than FLZ alone. The CC revealed better flowability, tabletability (tensile strength), compressibility, and compactibility. Moreover, Heckel and Kawakita analysis indicated the co-crystal to deform plastically, favoring improved compression. (4) <b>Conclusions</b>: The immediate drug release capabilities, improved hygroscopic stability, solubility, better antifungal activity, and flowability make FLZ-BA co-crystal a suitable candidate for the preparation of an immediate drug release dosage form. The study also revealed the application of co-crystal for improving the flowability and mechanical properties.