Generation of Hollow Crystals of a Drug with Lamellar Structure Forming Ability

Abstract

Hollow crystals are recognized for its higher surface area, which can be exploited for improving the dissolution rate of poorly soluble drugs. To date, no reports have emerged on the hollow crystal formation ability of drugs with lamellar structure, although rolling of the lamellar structure leading to the generation of inorganic hollow crystals is a well documented mechanism. In this work, for the first time, hollow crystals of fenoprofen calcium dihydrate were prepared and characterized. These novel hollow crystals are mostly rectangular in shape with a pore diameter ranging between 2 and 25 μm as confirmed from optical microscopy and scanning electron microscopy (SEM). Powder X-ray diffraction and diffraction scanning calorimetry analysis of the recrystallized samples indicate that the drug recrystallizes without transforming into an anhydrate form. The hollow crystals demonstrated an increased dissolution rate of drug when compared to the unprocessed drug, which was attributed to their increased surface area. Similarly, unlike the plain drug, the hollow crystals have shown acceptable plastic behavior during compression studies resulting in tablets at low pressure.