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

Solid dispersion is a common technique used for solubility enhancement of poorly soluble drugs. 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. 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. 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. 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.