Each era had its preferred chemical weapon:

• Hemlock killed Socrates in 399 BCE. Its active compound, coniine, paralyzes muscles from the extremities inward until breathing stops.
• Arsenic trioxide dominated Renaissance Italy. The Borgia family allegedly used it so often that "a Borgia dinner" became a euphemism for assassination.
• Lead acetate ("sugar of lead") sweetened Roman wine. Chronic lead poisoning may have contributed to the madness of several emperors.
• Strychnine, from the nux vomica tree, causes violent convulsions by blocking glycine receptors in the spinal cord.
• Ricin, from castor beans, blocks protein synthesis inside the ribosome.