Adreno is an addictive synthetic neurotransmitter enhancer also known as The Blue Devil.
Adreno, or The Blue Devil, has a small blue crystal-like appearance. During the war, it was used it to enhance physical performance. It's side effects can be dangerous and unpredictable. When used in battle, it can incite a killing frenzy. In other forms, it can function as an opiate. The wide range of effects is one of the reasons Adreno has been outlawed.
When the EMC ran out of the synthetic drug, an enterprising chemist came up with a formula using actual adrenal fluids. They scare someone, and drain them. While undergoing the process, victims hallucinate a series of terrifying events. Victims last about 10 hours before the process kills them.
Usage in the Show
In season 1, a dealer named Meeko uses a bioman named Ulysses to kidnap people and extract adrenal fluid from them. He normally kidnaps people whose disappearance will go largely unnoticed, but he kidnaps the mayor's sister, Kenya Rosewater, when she sees his truckload of victims. This leads both the mayor and the lawkeeper to hunt him down, and Meeko is killed by the end of the episode.
In season 2, Stahma Tarr has taken up adreno sales in Defiance and begun selling it to Amanda Rosewater. When Niles Pottinger wants to use Amanda's addiction to his advantage, he blackmails Stahma into getting out of the adreno business so that Amanda will be forced to come to him for the drug. Many people begin to go through withdrawals during this time. Amanda also experiences the violent outbreaks that result from adreno usage.