What we know about VMAT2-inhibitor-induced parkinsonism

Question from a Member: I have an older adult patient with chronic paranoid schizophrenia, stable and doing well on risperidone 6 mg/day, who developed tardive dyskinesia symptoms (blinking, tongue thrusting, “piano playing” finger, and toe movements).  I started him on valbenazine (Ingrezza®) 40 mg daily. Within 2 weeks, he was exhibiting full-blown Parkinsonism symptoms: mask-like…