Coumadin.
Otherwise known as Warfarin. Rat poison. Which, ironically, is a blood thinner for stroke and heart attack patients. Can kill if not properly monitored and controlled lest the patient die. Just as easily as rats who bleed to death from its use.
Ironically, many’s the human patient who has died, rat-like, by refusing to take it. “I’m not going to take that stuff; it’s just rat poison.”