This study evaluated the interaction between sodium polystyrene sulfonate (SPS) and several commonly used concomitant drugs, such as carvedilol, bisoprolol, imidapril, atorvastatin and azilsartan. The residual rate of adsorption 6 h after starting the experiment followed the order carvedilol (0.36%) < bisoprolol (19.7%) < imidapril (81.2%) < atorvastatin (86.5%) < azilsartan (87.9%) in artificial intestinal juice (pH 6.8). In addition, the pKa of carvedilol and bisoprolol was 8.0 and 9.6 and that of atorvastatin, azilsartan, and imidapril was 4.5, 6.1, and 2.4, respectively. These results indicate that the form (ionic or uncharged) of each drug is important to its reaction with SPS. Moreover, we demonstrated the effect of potassium ions (concentration of 1000 or 2000 mg/L) on the adsorption of concomitant drugs onto SPS in artificial intestinal juice. Our results show that the residual rate of adsorption of carvedilol and bisoprolol increases with increasing concentration of potassium ions whereas adsorption of potassium ions onto SPS was unaffected by carvedilol and bisoprolol under our experimental conditions. Finally, the obtained results revealed that interactions between SPS and carvedilol or bisoprolol readily occur in artificial intestinal juice.
Keywords: adsorption; potassium ion; sodium polystyrene sulfonate; β-blocker drug.