Kremezin^® is an oral adsorbent that has been used for improving uremic symptoms and delaying the initiation of dialysis in patients with chronic kidney disease. Kremezin causes various drug interactions by adsorbing molecules of coadministered drugs in the gastrointestinal tract. In human studies, reduction in plasma concentrations of several drugs including aspirin, amlodipine and triazolam has been reported when administered simultaneously with Kremezin. However, a dosing interval of 30 to 90 min between Kremezin and other drugs renders the interaction insignificant. With limited clinical evidence available currently, it is unlikely that the extent of drug interaction with Kremezin can be predicted accurately. Hence, simultaneous administration of Kremezin with other drugs should be avoided, especially for drugs with narrow therapeutic ranges. Careful monitoring of drug effects and markers including drug levels in serum or blood is necessary in case of concurrent use with Kremezin. (Jpn J Clin Pharmacol Ther 2013; 44(2): 77-84)