A lot of painkillers work on the brain level. Neurokinin-1 is a very specific receptor in the brain that ties into a very specific molecule that's been implicated in a lot of Liz's symptoms. Right now the main thing that acts on that molecule is opioids that have a lot of side effects, like being hella addictive. Medications that target neurokinin-1 (antagonists) have the potential to target symptoms of depression, dissociation, pain, and gastrointestinal problems all at once.