Strobolin

From Memory Alpha, the free Star Trek reference.

Strobolin is the cure for the choriocytosis virus.

Spock contracted the disease in 2270. The USS Potemkin obtained the drug and delivered it to the USS Huron. En route to the Enterprise to deliver the drug, the Huron was attacked by Orion pirates, who stole the drug and the ship's other cargo, dilithium. The Enterprise eventually recovered the drug and Leonard McCoy administered it to Spock, saving his life. (TAS: "The Pirates of Orion")