Final answer:
Magnesium sulfate is the main drug given for preeclampsia in hospitals to prevent and treat seizures associated with the condition.
Step-by-step explanation:
The main drug given for preeclampsia in a hospital is magnesium sulfate. This drug is crucial for preventing and treating seizures associated with preeclampsia, a condition characterized by high blood pressure and potential organ damage in pregnant women. Unlike the options warfarin and insulin, which serve other specific medical purposes such as anticoagulation and blood sugar regulation respectively, or acetaminophen which is a pain reliever, magnesium sulfate directly targets the preeclamptic state by providing neuroprotection for the mother.