JT is a 66 year old male with a past medical history of hypertension and GERD.  His current medications include hydrochlorothiazide, lisinopril, nifedipine, and omeprazole.  JT has been having significant facial pain and is diagnosed with trigeminal neuralgia.  So what are the options for treating trigeminal neuralgia?  Most often I’ve seen carbamazepine utilized first line, then potentially oxcarbazepine or gabapentin used next.

In the JT’s case, he was initiated on oxcarbazepine and did get some relief.  About one month following initiation of the oxcarbazepine, he was scheduled for routine labwork which included electrolytes.  The labs were unremarkable with the exception of sodium which was now at 124.  The previous sodium was 138.

He indicated that he did feel a little bit lethargic, so it was decided to discontinue the oxcarbazepine and switch to gabapentin.  He did get relief with initiation of the gabapentin, and the sodium did return to baseline upon discontinuation.

In this case, the hydrochlorothiazide did add some addition risk for the hyponatremia, and we could’ve potentially found an alternative there if it was deemed that the oxcarbazepine was essential, but there is no guarantee that the sodium would’ve returned to normal.  Using carbamazepine in place of oxcarbazepine in this case would’ve certainly been a risk as well as structurally they are similar and can both cause hyponatremia.

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