Drug misuse, intoxication and withdrawal Quiz: Ace Your Exams

A 35-year-old woman is brought to the emergency department because of altered mental status and slurred speech. Past medical history is significant for generalized anxiety disorder, major depressive disorder, and panic disorder. Current medications include amitriptyline and clonazepam. Temperature is 37.1°C (98.7°F), pulse is 80/min, respirations are 10/min, and blood pressure is 117/68 mmHg. Physical examination reveals a drowsy female who responds incoherently to questions. On neurological examination, pupils are 4 mm bilaterally and reactive to light. The abdomen is nontender, non-distended, and bowel sounds are normoactive. Lungs are clear to auscultation. There is no nystagmus or hand tremor appreciated. The patient tries to get up to use the restroom during the evaluation and nearly falls due to an ataxic gait. Laboratory results are shown below. Initial ECG is within normal limits. Which of the following is the most likely diagnosis?  

Laboratory value	Result
Sodium	140 mEq/L
Potassium	4.1 mEq/L
Chloride	102 mEq/L
HCO3-	24 mEq/L
Creatinine	0.6 g/dL
BUN	10 mg/dL
Glucose	120 mg/dL
AST	20 U/L
ALT	25 U/L
Total bilirubin	0.3 mg/dL
Alcohol	negative