Dissolution Kinetics of a BCS Class II Active Pharmaceutical Ingredient

Abstract

This paper presents a laboratory study examining the dissolution kinetics of ibuprofen crystals in water containing a phosphate buffer (pH 7.20) at 37 °C, examining the influences of initial undersaturation ratio, agitation rate, crystal habit, and particle size. For each experiment, the concentration during the dissolution process was followed using UV spectroscopy, ATR-FTIR, and FBRM methods. The dissolution profiles were correlated using eight mathematical models, and the dissolution rate parameters were determined. The Weibull model, the Korsmeyer–Peppas model, and the first-order kinetics model gave better correlation results than the other models used in this paper for the dissolution of ibuprofen crystals. The particle size distribution slightly shifted to the right after dissolution, confirming that smaller particles with higher surface areas dissolved more rapidly. During dissolution, two distinct behaviors were obtained at different levels of undersaturation ratio; therefore, it is postulated that the mechanism of dissolution switches from being mass-transfer-limited at higher levels of undersaturation ratio to being limited by the rate of surface detachment at lower undersaturation ratio levels.