What does the case suggest as a useful initial approach to determine the cause of subtherapeutic phenytoin levels?

What does the case suggest as a useful initial approach to determine the cause of subtherapeutic phenytoin levels?

• A. Explore medication adherence with the patient in a non-threatening manner.
• B. Accuse the patient of noncompliance.
• C. Ignore adherence and adjust dose.
• D. Assume nonadherence without discussion.

Answer: (A)

When phenytoin levels are subtherapeutic, the safest and most informative first move is to explore how the patient is taking the medication in a non-threatening, nonjudgmental conversation. This approach matters because misadherence is a common and correctable reason for low levels, and asking openly helps build trust so the patient feels comfortable sharing real-world patterns—whether doses are missed, taken too close together, or not taken at all. It also reveals practical barriers like forgetting, complex dosing schedules, cost, or access issues, which can be addressed without blame. If adherence checks out, you then investigate other factors such as drug interactions that speed up phenytoin metabolism, absorption problems, or issues with how the level was drawn (for example, whether it was a trough sample). Blaming or assuming nonadherence without discussion can derail proper care and overlook other causes.

When phenytoin levels are subtherapeutic, the safest and most informative first move is to explore how the patient is taking the medication in a non-threatening, nonjudgmental conversation. This approach matters because misadherence is a common and correctable reason for low levels, and asking openly helps build trust so the patient feels comfortable sharing real-world patterns—whether doses are missed, taken too close together, or not taken at all. It also reveals practical barriers like forgetting, complex dosing schedules, cost, or access issues, which can be addressed without blame. If adherence checks out, you then investigate other factors such as drug interactions that speed up phenytoin metabolism, absorption problems, or issues with how the level was drawn (for example, whether it was a trough sample). Blaming or assuming nonadherence without discussion can derail proper care and overlook other causes.