Assessing the binding interaction of polystyrene sulfonate with amitriptyline in healthy volunteers: a cross-over design — The BIND study

Purpose Polystyrene sulfonate is used for binding potassium in patients with chronic kidney disease (CKD). Because of its binding properties, it can potentially bind other medications and thereby decrease their bioavailability and effectiveness. Amitriptyline, often used by CKD patients for neuropathic pain, shows significant binding to polystyrene sulfonate in vitro . The purpose of this study was to determine the effect of polystyrene sulfonate on the exposure of amitriptyline in vivo when taken concomitantly in healthy volunteers. Methods We performed a prospective cross-over study in nine healthy volunteers. Participants were 18 years of age or older, did not use any medication, and had no known allergy to amitriptyline or polystyrene sulfonate. Participants visited Deventer Teaching Hospital twice. Once they received a single dose of amitriptyline 50 mg and once they received a single dose of both polystyrene sulfonate 15 g and amitriptyline 50 mg taken concomitantly, with a wash out period of at least 1 week. After intake of the medication, six blood samples were collected, at 2, 3, 4, 5, 6, and 8 h. Blood samples were analysed to determine maximum concentration (Cmax) and area under the curve 0–8 h after intake (AUC 0–8 h ). Difference in Cmax and AUC 0–8 h was analysed with a paired T -test or Wilcoxon signed rank test, depending on normality of the data. A p -value