RIPK1 and essential tremor: As a neuronal voltage-gated sodium channel blocker, primidone has been used for the treatment of epilepsy, essential tremor, and psychiatric disorders.11 We performed in vitro kinase assays using Flag-tagged murine full-length RIPK1 using p-S166 RIPK1 as a biomarker for the activation of RIPK1.12 ~50% reduction RIPK1 kinase activity was achieved in the presense of 0.1–1 μM primidone and complete inhibition of RIPK1 kinase activity was observed with concentrations of primidone greater than or equal to 10 μM (Supplementary Fig. 1).