Influence of polymers on oxaprozin dissolution kinetics and mechanisms

In this work, the influences of polymers (HPMC E3, PEG 6000, PVP K25, PVP K30), temperature, stirring speed and polymer mass fraction on the oxaprozin (OXA) dissolution profiles were measured by a United States Pharmacopeia (USP) Ⅱ dissolution apparatus. The two-step chemical potential gradient model combined with the interfacial steady-state mass transfer model as well as PC-SAFT (perturbed-chain statistical associating fluid theory) were used to analyze the dissolution mechanism of OXA under different conditions. The presence of polymer could promote the surface reaction of OXA while temperature and stirring speed have different influences on the surface reaction and diffusion. The diffusion boundary layer thickness δ $\mathrm{\delta }$ of OXA tablets increases with the increase of temperature and decreases with the increase of stirring speed. Based on the obtained surface reaction rate constant k s $k_s$ and diffusion rate constant k d $k_d$ , the dissolution profiles with high accuracy compared with the experimental data.