The story
Blend of Pfizer + ivermectin. Coined by conspiracy theorists in 2021. From the drug pharmacokinetics of nirmatrelvir being similar to ivermectin, and thus supposedly being evidence that Pfizer blocked ivermectin from use by issuing a newly patented medicine of the same function, similar to how drug companies block generic drugs by issuing minor variants of drugs soon to come off patent and receiving a new patent extension.
Etymology from Wiktionary, CC BY-SA 4.0.