The present disclosure generally provides complexes including a pharmaceutically active agent and a functionalized polymer, wherein the functionalized polymer includes repeat units, the repeat units including ionizable repeat units having at least one ionizable side group and/or ionizable end group, a plurality of the at least one ionizable groups forming non-covalent bonds with the pharmaceutically active agent. Polymers which may be used to form such complexes as well as methods of making and using the complexes and related compositions are also provided.
