PD173212 is a selective N-type voltage sensitive calcium channel (VSCC) blocker, with an IC₅₀ of 36 nM in IMR-32 assays. IC50 & Target: IC50: 36 nM (VSCC)^[1] In Vitro: PD173212 (PD 173212, 300 nM) potently blocks recombinant B-class (N-type) calcium channel currents 78±7.8%, with an IC₅₀ of 74 nM, by whole-cell voltage-clamp techniques. PD 173212 possesses selectivity for non L-type Ca²⁺ channels versus neuronal Na⁺, K⁺, and L-type Ca²⁺ channels^[1]. In Vivo: PD173212 (30 mg/kg, i.v.) shows moderate efficacy in preventing tonic seizures in the audiogenic seizure model^[1].