Improved Dissolution Behavior of Fenbufen by Spherical Crystallization

Abstract

Fenbufen is an analgesic, antipyretic and anti-inflammatory drug that is characterized by poor water solubility, a defect increased by very low wettability. Poor water solubility, particularly at low pH, could decrease absorption in the upper part of the gastrointestinal tract, which would be inconvenient for good bioavailability. Different spherical crystallization processes have been considered as methods to improve fenbufen dissolution behavior. A two-solvent system, in the presence of a bridging liquid, is the only method capable of producing spherical fenbufen crystals. In a first step, fenbufen solubility was considered in different solvents. The drug crystals formed were typically needle shaped. This characteristic was considered as a favorable parameter to obtain spherical crystals. After the selection of the best fenbufen solvent, several ratios of solvent (S)–nonsolvent (NS) (tetrahydrofuran [THF]–demineralized water) were studied. The addition of a bridging liquid (isopropyl acetate) improved spherical crystallization. The results from this method were reproducible batch to batch. The spherical crystals obtained showed a clear improvement in dissolution capacity, probably due to better wettability. Dissolution studies were then carried out on these spherical crystals stored for 1 month at different relative humidities (RHs). The dissolution profiles remained unchanged.