Prediction of drug interaction between oral adsorbent AST-120 and concomitant drugs based on the in vitro dissolution and in vivo absorption behavior of the drugs

AST-120 is used to decrease the abundance of serum uremic toxins in treatment of chronic kidney disease; however, it could also adsorb concomitantly administered drugs. This study aimed to develop a prediction method for drug interaction between AST-120 and concomitantly administered drugs based on in vitro dissolution and in vivo absorption behavior. Sixty-eight drugs were selected for the analysis. For each drug, theoretical dissolution (R (d)) and absorption (R (a)) rates at estimated dosing intervals (1, 30, 60, 90, 120, and 240 min) were calculated using the Noyes-Whitney formula and compartment analysis, respectively. The optimal thresholds for R (d) and R (a) (R (dth) and R (ath)) were estimated by comparing the results with those of previous drug interaction studies for six drugs. Four drug interaction risk categories for 68 drugs at each dose interval were defined according to the indices of dissolution and absorption against their thresholds. The in vitro dissolution and in vivo absorption behavior of the selected drugs were well fitted to the Noyes-Whitney formula and one- or two-compartment models. The optimal R (dth) and R (ath) that gave the highest value of consistency with the equivalence of drug interaction studies were 90 and 30 %, respectively. As the dosing intervals were lengthened, the number of drugs classified into the low-risk categories increased. A new drug interaction prediction method based on the pharmacokinetic parameters of drugs was developed. The new model is useful for estimating the risk of drug interaction in clinical practice when AST-120 is used in combination with other drugs.