Phrixotoxin 3-NH2 TFA is a derivative of Phrixotoxin 3 TFA. Phrixotoxin 3 TFA is a potent blocker of voltage-gated sodium channels , with IC 50 s of 0.6, 42, 72, 288, 610 nM for NaV1.2 , NaV1.3 , NaV1.4 , NaV1.1 and NaV1.5 , respectively. Phrixotoxin 3 TFA modulates voltage-gated sodium channels with properties similar to those of typical gating-modifier toxins, both by causing a depolarizing shift in gating kinetics and by blocking the inward component of the sodium current.