The invention relates to the detection and/or removal of conformationally altered proteins and/or molecules comprising a cross-β structure from a pharmaceutical composition. Disclosed is that unwanted and/or toxic side effects of pharmaceuticals are caused by proteins present in the pharmaceutical and adopting a cross-β structure conformation. Further disclosed is a method for detecting a protein in a pharmaceutical composition, the method comprising: contacting the pharmaceutical composition or any of its constituents comprising a protein with at least one cross-β structure-binding compound resulting in a bound protein and/or peptide comprising a cross-β structure and detecting whether bound protein and/or peptide comprising a cross-β structure are present in the pharmaceutical composition or any of its constituents comprising a protein. Further described are methods for removing cross-β structures from a pharmaceutical composition and controlling the manufacture of a pharmaceutical composition.
