I don't want to mention it's common name specifically, as this is rare enough that it could be linked to me personally. It is actually an antibiotic (I'd someh

I don't want to mention it's common name specifically, as this is rare enough that it could be linked to me personally. It is actually an antibiotic (I'd somehow forgotten that - edited my original comment now!), but once that acts as a immunosuppressant, and it's less-common name is diaminodiphenyl sulfone.