Antizin is an intravenous antiviral drug that acts as a temporary cure for the Harran virus in Dying Light. The Global Relief Effort (GRE) regularly deploys airdrops filled with Antizin into Harran. Some survivors can be notified via television link, like Harris Brecken in the headquarters of The Tower.
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 mission Airdrop.