Zetekitoxin AB (ZTX) is a guanidine alkaloid found in the Panamanian golden frog Atelopus zeteki.

It's structurally related to saxitoxin, but with some differences.

[2] ZTX is an extremely potent sodium channel blocker.

It has been shown to block the voltage-gated sodium channels at picomolar concentrations.

[2] ZTX is an extremely potent neurotoxin.