It wasn't the first time that Katherine used Adrifin. She almost died due to hypothermia in a past mission in Germany, and that was her only chance of survival.
The way it worked, once the drug was administered, the heart rate would increase, and a boost of energy would course throughout the body—pretty much similar to an adrenaline rush—only this drug gave her several folds of energy surge in her body.
What Katherine hated about it were the side effects. It wasn't the same for everyone, but she would be sick for days as it wore off. Apart from nausea and anxiety, she'd have internal tremors. It was a helpful drug for survival, but the adverse effect was awful.
