Ketracel-white

The slang term is "White".

A white liquid drug -- characterized by Deep Space Nine's chief medical officer, Doctor Bashir, as an "isogenic enzyme" -- to which the Jem'Hadar were genetically bred to addiction by the Founders.

As distributed by Vorta field supervisors, the standard Jem'Hadar uniform includes a tube that carries the ketracel-white from a replaceable holding vial in the collarbone area directly into the neck. Without "white," Jem'Hadar exhibit almost immediate and severely painful withdrawal symptoms, some of which include weakness, extreme tactile sensitivity, and apparent abdominal pain. The end result is finally death.

This information taken from http://www.startrek.com/

On Stardate 21402.16 Doctor (then Lieutenant) Jack Ristone successfully manufactured Ketracel White. Doctor Jack Ristone began researching the ability to synthesize the substance two years earlier while serving alongside Jem'Hadar on the NCC (eventually USS) Avenger. Although by the time Ristone actually managed to create the K-W all of the Jem'Hadar had been killed in combat the achievement was none-the-less impressive.

It had been known for some time that K-W was an isogenic enzyme. Doctor Ristone however discovered that it was largely made up of Yridium bicantizine which was rather difficult to recreate. Jack's big break was discovering that he could synthesize the yridium bicantizine by breaking down tri-nucleic fungi which were native to the planet Kabrel-I. From there is was simply a mattering of tinkering and perfecting the exact chemical makeup of the rest of the K-W which was difficult though thankfully possible due to the advancements in Star Fleet technology.