Ketracel-white
Ketracel-white (or simply white) was a chemical compound created to be an addictive narcotic that contained an isogenic enzyme. One of the active ingredients of white was yridium bicantizine. The Jem'Hadar soldiers of the Dominion were genetically-engineered to lack the enzyme which white provided, and required frequent doses of the drug to survive. The white also provided all the nutrients they required, alleviating them of the need to eat or drink. 

Without white, Jem'Hadar soldiers suffered withdrawal symptoms including pain, anxiety, loss of mental control, and inability to "shroud"; eventually, the Jem'Hadar spiraled into homicidal insanity. First killing their enemies followed by their allies, they inevitably turned on each other. Ultimately, their entire genetic structure collapsed. () On rare occasions, a Jem'Hadar was born with a genetic mutation which allowed their bodies to produce the white they needed, though most such instances went unnoticed, as the Jem'Hadar with this mutation still took the drug on a regular basis and were unaware that they had no need to. () All known attempts to remove this genetically-engineered addiction failed, with the drug itself proving difficult to analyze and replicate by Starfleet methods. It was determined that a dose of three cc's provided a sufficient amount to  subside the patient's angst. ()

The addiction to white ensured the Jem'Hadars' loyalty to the Founders. However, for most Jem'Hadar, this was unnecessary, as their loyalty was already absolute. Distribution of the white was controlled by the Vorta, and was dispensed to the Jem'Hadar  in a formal ceremony:

Vorta: "First [name], can you vouch for the loyalty of your men?"
Jem'Hadar: "We pledge our loyalty to the Founders, from now until death."
Vorta: "Then receive this reward from the Founders, may it keep you strong."

Jem'Hadar bred in the Alpha Quadrant (called "s") occasionally dispensed with the formal ceremony, claiming that their loyalty was shown by their actions rather than their words. () In the event of the death of the Vorta or the detachment of a group of Jem'Hadar from their main unit, the Jem'Hadar First could unlock the white case. ()

Early in the Dominion War, the Dominion suffered from a white shortage due to a minefield preventing the shipment of new supplies from the Gamma Quadrant. The shortage was exacerbated when the primary white storage facility was destroyed by Starfleet. In a secret memorandum, Damar recommended that the last white supplies be poisoned if new supplies could not be procured. ()

After Operation Return, the Dominion attempted to acquire the Kabrel system from the Federation under the guise of peace negotiations, as the tri-nucleic fungi on Kabrel I would have enabled them to manufacture an unlimited quantity of white. () Later, the Son'a agreed to produce large amounts of white for the Dominion on Devos II. (; )

Appendices

Background information 
The tubes that delivered the white to the Jem'Hadar evolved in design during the third and fourth seasons of . Originally, the tubes were colored black in , then white in , then transparent in . The tubes remained transparent throughout the rest of the series. 

They also became more elaborate, however, becoming bigger and mechanized. "It was [at first] supposed to be something that was very subtle, that went into the main blood vein in their necks," recalled Michael Westmore, following his work on season four. "Eventually, it was thought that that was a little boring, so now when we see them, there's an actual motor in their costume which keeps circulating a flow of liquid through the tube. That was added about the third or fourth time they worked." (Star Trek: Deep Space Nine - The Official Poster Magazine, No. 3) 

Special Effects Supervisor Gary Monak recollected, "Tiny pumps that came out of copy machines seemed to work the best, in terms of the speed and the sound. The first time we had to do a bunch of Jem'Hadar, we got twelve of these pumps from a surplus place, and they all worked fine. But the next time it came up and we needed more, they no longer existed. We had gotten the last twelve pumps that work." Smiling, Monak concluded, "It might be touch and go if they ever send thirty of these guys to us looking for neck pumps." ()

Apocrypha 
In Star Trek Online, ketracel-white is revealed to have been derived from a fungus found on the Hur'q homeworld. The Dominion hoped to use the earliest form of ketracel-white to control the Hur'q, but discovered that this was impossible as, without the substance, they became non-sentient and extremely aggressive. The Changelings nonetheless refined ketracel-white and engineered the Jem'Hadar and the Fek'Ihri in the hopes of using it, with the Jem'Hadar ultimately being the successful experiment. After the Hur'q threat is over, the Dominion, now under the control of Odo, removed the genetic dependency of ketracel-white from Jem'hadar as a condition to join the Alliance.

References

External link
 

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ja:ケトラセル・ホワイト
nl:Ketracel-wit
Drugs