Improvement of solubility of sparingly water-soluble drug triggered by metal-organic framework

Metal-organic frameworks (MOFs) are a new class of porous materials consisting of metal ions and organic ligands. The present study demonstrated a novel improvement technology of drug solubility based on MOFs. Zeolite imidazolate framework-8 (ZIF-8) was selected as a model MOF, while the analgesic and antipyretic indomethacin (IDM) was selected as a model poorly water-soluble drug. The loading test of IDM onto ZIF-8 particles indicated that IDM was loaded by deposition on the particle surface. The amount of IDM loaded on ZIF-8 was found to be 1.21 g IDM/g ZIF-8. X-ray diffraction measurements revealed that the IDM loaded on ZIF-8 assumed a new crystal phase similar to the eta-form IDM. Finally, water solubility of IDM loaded on ZIF-8 was 45 times higher than that of the original gamma-form IDM. It was concluded that use of ZIF-8 MOF dramatically improves water solubility of active pharmaceutical ingredients.