TTX is a potent marine-derived neurotoxin that reversibly inhibits the inward sodium current through voltage-activated sodium (Nav) channels, blocking nerve and muscle action potentials. It inhibits the Nav current in frog muscle and squid axon with IC50 values of 4.1 and 5.2 nM, respectively, and binds to rat brain membranes with a Kd value of 1.8 nM. TTX was used in Hodgkin and Huxley’s classic experiments to elucidate the physical biology of nerve action potentials and remains an indispensible neuroscience tool to pharmacologically dissect the contribution of the Nav current in excitable neurons and to rationally design compounds for the treatment of neuropathic pain. This citrate-stabilized form of TTX is designed for improved solubility over pure TTX , which is insoluble in water and most organic solvents. This preparation of TTX citrate consists of TTX that has been dissolved in a citrate solution and then lyophilized.
