IC50: 3.4 μM (K ⁺ -stimulated intracellular Ca ²⁺ -elevation)

NS-638 dose dependently inhibits K ⁺ -stimulated [45 Ca ²⁺ ]-uptake in chick cortical synaptosomes and 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA)- stimulated [ ³ H]GABA-release from cultured cortical neurons with IC ₅₀ values of 2.3 and 4.3 μM, respectively. K ⁺ -stimulated intracellular Ca ²⁺ -elevation in cultured cerebellar granule cells is equipotently blocked with an IC ₅₀ value of 3.4 μM. At this concentration no effect on Ca ²⁺ -induced contractions in K ⁺ -depolarized guinea pig taenia coli is observed. NS-638 reversibly blocks N- and L-type Ca ²⁺ -channels in cultured chick dorsal root ganglion cells in the concentration range of 1-30 μM.

In the mouse middle cerebral artery occlusion model, NS-638 administered i.p. (50 mg kg-1) at 1 h and 6 h post-ischemia, and once a day for the next two days, results in a 48% reduction in total infarct volume. It does not show protection against ischemic neuronal damage in the gerbil model of bilateral carotid artery occlusion.