Tetramethylenedisulfotetramine

Tetramethylenedisulfotetramine (TETS, DSTA, also called tetramine) is a toxic organic chemical. Its chief application is as a rodenticide (rat poison). It is uncommon and therefore little known. Its chemical formula is C4H8N4O4S2 and its chemical name is 2,6-dithia-1,3,5,7-tetraazatricyclo(3.3.1.1(3,7)-decane 2,2,6,6-tetraoxide). It is an odorless, tasteless white powder. It is slightly soluble in water, DMSO and acetone, and insoluble in methanol and ethanol. Its melting point is above 270 °C. . It is a sulfamide derivate. When crystallized from acetone, it forms cubic crystals.

It can be encountered also under names Dushuqiang, Four-two-four, 424, NSC 172824, Meishuming, and Shanbudao.

TETS is a neurotoxin, causing lethal convulsions. Its effect is similar to picrotoxin, another cage convulsant. It is one of the most hazardous pesticides. It is 100 times more toxic than potassium cyanide. It might be more powerful convulsant than strychnine. It is a non-competitive GABA antagonist and binds irreversibly to neuronal GABA receptors and disables chloride channels, disabling the activity of neurons. There is no proven antidote. Lethal dose for humans is considered to be 7-10 milligrams. Poisoning is diagnosed by gas chromatography and the treatment is mainly supportive, with large doses of benzodiazepines and pyridoxine. 

It is retained in tissues of poisoned poultry and animals, posing a risk of secondary poisoning by eating their meat.

Its use worldwide is banned since 1984, but due to continuing demand and ease of production it is still readily, though illegally, available in mainland China and can be found in some illegally imported rat poisons. The best known Chinese rodenticide, containing about 6-20% TETS, is Dushuqiang, "very strong rat poison". It was used for mass poisonings in China; in April 2004 there were 74 casualties after eating scallion-flavored pancakes tainted by their vendor's competitor, in September 2002 in China 400 people were poisoned and 38 died by contaminated food, and in May 2002 there was one documented case of accidental poisoning in the US.