Final answer:
Lithium, Dilantin, and Digoxin are medications used to treat various medical conditions. They can be toxic if levels in the blood become too high.
Step-by-step explanation:
Lithium is commonly used to treat bipolar disorder, helping to stabilize mood and prevent manic episodes. However, it can be toxic if levels in the blood become too high. Dilantin is an anti-seizure medication used to control and prevent epileptic seizures. If levels of Dilantin in the blood become too high, it can lead to toxicity. Digoxin is a medication used to treat certain heart conditions, such as congestive heart failure and atrial fibrillation. It helps to improve heart function, but excessive levels can be toxic.