Borathium is a drug.
In 2368, Toby Russell used borathium on a patient who had died. Beverly Crusher thought Toby Russell might have used morathial or leporazine, although Russell felt the newly created borathium was decades ahead. (TNG episode: "Ethics")
In 2371, Julian Bashir thought about using borathium to treat Bryth if a cycle of morathial and leporazine proved ineffective. (DS9 - Deep Space Nine Special comic: "Oaths")