The drug is used to manage a condition suffered by telepaths where a virus like organism (likely engineered by Psi Corps) that over time subverts and replaces the brain's glial cells with mutant cells that mimic the normal cells function. With mundanes the process is essentially harmless as the mutant cells perform the same task as those they replace, however in telepaths, they stimulate the production of certain neurotransmitters that don't naturally occur within the human body. Initially these neurotransmitters act like stims, increasing the processing of telepathic information and impulses, providing an enhanced boost to a teep's abilities. This is increased cognition and heightened senses is accompanied by a sense of euphoria though inevitably, the neurotransmitter starts overproducing and begins triggering functions without threshold electrical potential, essentially short-circuiting the network of cells and resulting in hallucinations, seizures and eventually the collapse of the nervous system.
The condition is resistant to gene tampering so choline ribosylase is the only known treatment. Fortunately the drug is proven to be 100% effective, provided it is taken on schedule; once a month.