Subtherapeutic serum quetiapine concentrations after absorption inhibition by binding resins: a case report

Summary What is known and objective Polystyrene sulfonate and sevelamer are binding resins that are used in the treatment of, respectively, hyperkalemia and hyperphosphatemia. It is unknown whether these resins interact with the antipsychotic quetiapine. Case summary We report on a woman with unexplainable low serum quetiapine concentrations who also used the binding resins polystyrene sulfonate and sevelamer. An In vitro binding assay showed binding of quetiapine by these resins. Separation of the ingestion times of quetiapine and the binding resins resulted in increased serum levels in this patient. What is new and conclusion Polystyrene sulfonate and sevelamer are able to bind quetiapine. Healthcare professionals should be aware of this potential drug–drug interaction as this could lead to antipsychotic treatment failure. The antipsychotic drug quetiapine is bound by polysterene sulfonate and sevelamer after co‐administration resulting in sub therapeutic serum levels.