In Dead Rising 2: Off The Record, Zombrex is the most important item you should know. It is an anti-zombie infection drug and you are required to take a dose of when you are infected to keep yourself from turning into a zombie.
There are several locations, you will find this drug at. You only need one dose to unlock the corresponding achievement or trophy but I would try to add as many locations as possible where you can find Zombrex.
Dead Rising 2: Off The Record Zombrex Locations
Location. Search inside the Pharmacy at Roy’s Mart.
Location. You can purchase one doze from Pawn Ship in Moe’s Magination. It will cost you $50,000.
Location. Search inside bank vault security box number 673. You will find the key to unlock this box as you follow the reported by the exit to the central security room.
Location. You can find this one on the roof of the safehouse behind the elevator, just beside the assault rifle.
Location. In the Uranus Zone, this one is on the second story of the Jump Space 7 Restaurant in the VIP lounge, where you will have to break the glass window and then go through it to find it.
Location. This one is inside the underground tunnel near the ladder that leads to the Silver Strip.
Location. In the Uranus Zone, you will find the zombrex inside the safe deposit #673. The key to the deposit is on the floor of the Fortune City Hotel near the south plaza.
Location. Again, in the Uranus Zone, in the safe deposit #999. You will find the key inside the fountain of the Atlantica Casino.