The older adult patient is brought to the emergency department with sudden onset confusion, agitation, and hallucinations. The patient's past medical history is significant for type 2 diabetes managed with glyburide, anxiety managed with lorazepam, and insomnia managed with zolpidem. Upon assessment, the patient's heart rate and rhythm are regular, lungs are clear to auscultation, and bowel sounds are present. Vital signs are normal, with exception of a slightly elevated heart rate. Which is the most likely cause of the patient's symptoms?
Rationale
This patient presents with signs and symptoms of delirium, namely sudden onset confusion, agitation, and hallucinations. Medication toxicity is the most common reversible cause of delirium. In addition, in the elderly, even medications at therapeutic doses and levels can cause delirium. Although the patient is tachycardic, this is likely more related to the patient's agitation than dehydration. The patient's other vital signs are normal, so dehydration and pneumonia are less likely. Illicit drug use is not indicated in the question, so withdrawal is unlikely.
