Preparation and in vitro characterisation of nanofibers for enhancing the water solubility of poorly soluble drugs

Background and Aims: As the drug discoveries of the modern century have led to a rapid increase in the number of new drug candidates with low water solubility, nanofiber drug delivery systems have become a promising technology to increase the water solubility of drugs with a high surface-to-volume ratio. In this study, we aimed to prepare a nanofiber of a molecule with low water solubility and investigate its changing solubility properties. Methods: Three nanofiber dosage forms containing olanzapine (OLZ) active substance were developed by the electrospinning method using polyvinyl alcohol (PVA) polymer. Drug loading efficiency, zeta potential determination, electrical conductivity, rheology, field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analyses were performed to evaluate the in vitro characterisation of the formulations. The solubility profile of the optimised formulations in pH 7.4 phosphate buffer was evaluated. The stability of optimised formulations was evaluated in terms of physical properties (colour, shape, weight, diameter, and thickness) and drug amount for 35 days. Results: It was determined that the electrospinning property of the nanofiber preparation solution increased with the addition of ethanol to the polymer solvent medium. The active substance distribution in the nanofiber layer was more homogeneous in the N78 and N79 coded formulations with high zeta potential values compared to N69. Contrary to the homogeneous distribution problem, the loading efficiency of the N69-coded formulation containing chloroform (~29%) was higher than that of N79 (~9.8%). A 24-h solubility study in pH 7.4 phosphate buffer of the N78-coded formulation, which has an active ingredient loading efficiency of ~80.4%, confirmed the increased solubility of OLZ in water in the nanofiber drug delivery system. Conclusion: Further studies are needed to convert these model formulations into final drug products.