A 65-year-old female with metastatic non-small cell lung cancer (NSCLC) of squamous cell histology presents with nausea/vomiting and changes in mental status. She is due for day 8 gemcitabine.
History Seven days ago, the patient received cycle 2 of cisplatin and gemcitabine for her NSCLC. The patient’s husband states that his wife took antiemetics as directed, but noticed she had become disoriented and confused over the last 2 days. She is still taking her antiemetic prochlorperazine every 4 hours with minimal relief.
Her medical history includes hypertension and Stage IV NSCLC with bone metastasis. She was taking the following medications: hydrochlorothiazide 25mg daily, prochlorperazine 10mg every 4 hours as needed for nausea/vomiting, dexamethasone 8mg daily for 3 days postchemotherapy, and aprepitant 80mg daily for 2 days postchemotherapy.
Her laboratory test results were as follows:
Na 140mEq/L WBC 4.5
K 3.4mEq/L Hgb 12g/dL
CL 110mEq/L Plts 140
CO2 24 Albumin 2.4g/dL
What is the likely cause of the patient’s nausea/vomiting and mental status changes?
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