A client's plasma level of an antiepileptic drug (AED) is very high. The client is at risk for what?

• A. Seizure recurrence
• B. Dehydration
• C. Drug toxicity
• D. Hypertension

Answer: (C)

When an antiepileptic drug level is very high, the main risk is drug toxicity because many AEDs have a narrow therapeutic window. Exceeding that window means the body is exposed to too much of the drug, leading to toxicity rather than just extra seizure protection. Toxicity manifests as central nervous system effects such as drowsiness, dizziness, ataxia, slurred speech, and nystagmus, with confusion or decreased level of consciousness in more severe cases. Some AEDs can also cause organ-specific toxicity (like liver or bone marrow effects) at high levels, depending on the medication. Dehydration or hypertension aren’t the direct consequences of elevated AED levels, and the concern here is the toxic effects of having too much drug in the system.