Enzyme inhibitor developed by the Hoffan people which prevents a Wraith from feeding on a human. Originally developed by Farrol Mylan, the drug was in an experimental limbo for approximately 150 years until advanced aid from Earth's Atlantis expedition (namely Dr. Carson Beckett) solidified the prototype, changing the molecular design so it could be absorbed by the human body.
The experimental prototype was injected in a terminally ill patient, Merell, who entered the cell of the captured Wraith nicknamed "Steve." Steve found he was unable to feed on Merell, and he soon took on a peculiar, weakened state before he died.
This was an unintended side effect. Instead of simply preventing a Wraith from feeding, a portion of the drug re-enters their bodies along the feeding tubule and kills them.
The Hoffan drug is also fatal to approximately fifty percent of the recipients, but because of the resoluteness of the Hoffans, 96 percent of the entire population voted in favor of disseminating the prototype to the people. The half that survived would be immune, and would potentially raise offspring that possessed a form of immunity as well.
Poisoning the Well - With the aid of the Atlantis expedition production on the Hoffan drug nears its completion after 150 years.
The Kindred, Part 1 - Atlantis discovers that Michael has used Dr. Beckett's knowledge of the Hoffan drug to recreate it, using it to taint the Wraith's food supply all over the galaxy.