Antizin is a injected antiviral drug that acts as a temporary cure for the Harran virus in Dying Light. The Global Relief Effort (GRE) regularly send airdrops filled with it into Harran, and some survivors can be notified via television link, like Harris Brecken in the headquarters of The Tower, Kyle Crane Took Some From Dr. Zere At The Start Of The Game Before The Misson First Assignment.
A fake antizin is a quest item for the side quest "Goodnight Mr. Bahir".
In the Dying Light demo Antizin was shown in the mission airdrop demo game as a "suppressant". Kyle Crane also burnt crates full of Antizin, as by the command of the GRE in the misson Airdrop.