A movie about humans turning into giant hulk like monsters

Hello. Looking for a probably 1990s or 2000s sci-fi action movie. It’s about a group of people that find boxes of tray shaped liquid drug bottles. As I remember poorly, they were transporting these with a train. when somebody drinks from these bottles, they turn into giant hulk like monsters for a limited time. and when they get hit the time limit becomes shallower. I remember a last battle between a crazy man drinking a lot of the liquid and another one trying to defeat him with much less of the drug and the scene was in some sort of a big old abandoned church.