Preparation of a novel starch-derived three-dimensional ordered macroporous carbon for improving the dissolution rate and oral bioavailability of water-insoluble drugs

• 3DOMC is prepared and used to improve the solubility and bioavailability of drugs.
• When combined with osmotic pump technology, the drug release rate can be regulated.
• 3DOMC can inhibit the crystallization of drugs and maintain them in an amorphous state.

In our study, soluble starch was applied as a novel carbon source for preparing three-dimensional ordered macroporous carbon (3DOMC) using monodisperse silica nanospheres as the hard template. The 3DOMC was used as an insoluble drug carrier when it was found that it could markedly improve the water solubility of felodipine (FDP). The structural features of 3DOMC were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The 3DOMC structure was found to have a higher drug loading than microporous and mesoporous structures, and the interconnected nanostructure effectively inhibited the formation of drug crystals. FDP, belonging to the Biopharmaceutics Classification System II (BCSII), was chosen as the model drug and was loaded into the 3DOMC structure by solvent evaporation. The state of FDP in the 3DOMC structure was characterized by powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The results obtained showed that FDP was present in the pores in an amorphous or microcrystalline state. In vivo and in vitro experiments indicated that 3DOMC could significantly improve the drug dissolution rate, but the FDP-3DOMC self-made common tablets had the disadvantage of a burst effect. For this reason, osmotic pump technology was used to control the drug release rate. We developed a potentially useful insoluble drug carrier for pharmaceutical applications.

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