Enhanced Oral Bioavailability and Stability Studies of Loratadine Tablets Based on Solid Dispersion of Modified Ziziphus spina-christi Gum

Background: Solid dispersion is a common technique used for solubility enhancement of poorly soluble drugs. Objective: In this study, loratadine (LOR), a class II biopharmaceutical classification system (BCS), was formulated as solid dispersion tablets using modified Ziziphus spina-christi gum (MZG) as a carrier. Methods: The solvent evaporation method was used for LOR-MZG solid dispersion (SD) preparation. A variety of tests were conducted to characterize and optimize the formulation. Solubility, Fourier transform infrared (FTIR) analysis, Differential Scanning Calorimetry (DSC), X-Ray Diffraction (X-RD), and Scanning Electron Micrograph (SEM) of solid dispersions were carried out. Accelerated stability testing and pharmacokinetic studies of formulated tablets were also performed using albino Wistar rats. Results: Solid dispersion improved the solubility of LOR by 51 folds. FTIR spectra excluded drugpolymer interactions, and results obtained by DSC, X-RD, and SEM proved the transition from the crystalline to the amorphous state. The stability of LOR-MZG solid dispersion tablets was found to be better when the Alu-Alu package was used. The pharmacokinetics of LOR-MZG compared to MZG-free loratadine tablets (LOR pure) and commercial loratadine tablets (LOR-TM) following oral administration revealed that about 6 folds and 10 folds bioavailability were achieved with LOR-MZG compared to LOR pure and LOR-TM, respectively. Conclusion: Such promising results encourage more studies on MZG to be used for improving the aqueous solubility and bioavailability of a wide range of poorly soluble drugs.