Preparation, characterization and in vitro evaluation of melatonin-loaded porous starch for enhanced bioavailability

The present work aimed to apply porous starch (PS) as carrier to improve the oral bioavailability of poorly soluble drug melatonin (MLT). The drug loading and encapsulation efficiency of MLT-loaded porous starch (MPS) were optimized. The characteristics of MPS were analyzed using scanning electron microscopy, Brunauer-Emmett-Teller surface area, Fourier-transform infrared spectroscopy, x-ray diffraction, differential scanning calorimetry and thermo gravimetric analysis. Most MLT transformed into their amorphous form in the PS pores. MPS showed higher MLT solubility and cumulative release rate compared with raw MLT in SGF and SIF. MPS exhibited a higher inhibition to DCFH-DA-oxidized peroxyl radicals at a lower EC50 than that of the raw MLT. Furthermore, the plasma concentrations of MLT and MPS reached a Cmax of 134.26 and 291.77 ng/mL at 15 and 20 min, respectively. The AUC0-360min of the formulated MPS-treated group was approximately 2.34-fold higher than that of raw MLT.