Probable boceprevir-induced hyponatremia in a patient with chronic hepatitis C.

Purpose: A probable case of severe drug-induced hyponatremia associated with boceprevir use is reported.

Summary: A 55-year-old woman was started on boceprevir (800 mg orally thrice daily) during week 5 of triple therapy for chronic hepatitis C. Her serum sodium concentration the morning before starting boceprevir use was 140 mmol/L. After the fourth dose of boceprevir, the patient developed progressive dizziness leading to eventual loss of consciousness. She was taken to the emergency department (ED), where her serum sodium concentration was measured as 126 mmol/L; boceprevir use was temporarily discontinued. The patient's symptoms improved with infusion of 0.9% sodium chloride injection, and she was discharged home the same day. After resuming boceprevir use that evening, the woman developed extreme dizziness and headache upon awakening the next morning. On her return to the ED later that day, she had a serum sodium value of 134 mmol/L and was admitted to the hospital for monitoring and evaluation. Over the next three days, her symptoms improved with additional infusion therapy and discontinuation of boceprevir. The patient continued to receive dual therapy (peginterferon alfa-2a and ribavirin) without further documented serum sodium instability. Using the adverse drug reaction probability scale of Naranjo et al., the case was assigned a score of 5, indicating a probable reaction to boceprevir.

Conclusion: Soon after initiating boceprevir use as part of hepatitis C triple therapy, a woman required hospitalization for probable drug-induced hyponatremia, which resolved with discontinuation of the medication.