From the FDA Drug Label
Metabolism and nutrition disorders: hyponatremia The FDA drug label for Gabapentin indicates an association with hyponatremia (low sodium levels) as it is listed under metabolism and nutrition disorders in the postmarketing experience section 1.
- Hyponatremia is reported as an adverse reaction in the postmarketing use of gabapentin.
- The causal relationship to drug exposure is not established due to the voluntary nature of the reports.
From the Research
Gabapentin is associated with a low risk of hyponatremia, particularly during the initial treatment period, and patients taking this medication should be monitored for symptoms of low sodium levels, especially if they are older adults, have pre-existing kidney problems, or are on other medications that can lower sodium levels. The risk of hyponatremia with gabapentin is considered low compared to other antiepileptic drugs, with an adjusted odds ratio (OR) of 1.61 (1.08-2.38) for newly initiated treatment and 0.83 (0.64-1.06) for ongoing treatment, as reported in a population-based case-control study 2.
Key Considerations
- Patients on gabapentin should be monitored for symptoms of hyponatremia, such as headache, confusion, nausea, weakness, and in severe cases, seizures or coma.
- The risk of hyponatremia appears to be higher during the first few weeks of treatment with gabapentin.
- Management of gabapentin-induced hyponatremia typically involves reducing or discontinuing the medication if hyponatremia is confirmed and clinically significant.
- Fluid restriction may be necessary in symptomatic cases, and severe cases might require hypertonic saline.
- The mechanism behind gabapentin-induced hyponatremia is thought to be related to either inappropriate antidiuretic hormone secretion (SIADH) or direct effects on renal tubules.
Recommendations for Clinical Practice
- Healthcare providers should consider baseline sodium testing before starting gabapentin in high-risk patients and follow-up testing if symptoms develop, especially during the initial treatment period.
- Patients taking gabapentin should be educated on the symptoms of hyponatremia and the importance of reporting these symptoms to their healthcare provider promptly.
- Alternative medications with a lower risk of hyponatremia should be considered for patients who develop this condition while taking gabapentin.