From the FDA Drug Label
Overdosage A lethal dose of gabapentin was not identified in mice and rats receiving single oral doses as high as 8000 mg/kg. Signs of acute toxicity in animals included ataxia, labored breathing, ptosis, sedation, hypoactivity, or excitation. Acute oral overdoses of gabapentin up to 49 grams have been reported In these cases, double vision, slurred speech, drowsiness, lethargy, and diarrhea were observed. All patients recovered with supportive care. Coma, resolving with dialysis, has been reported in patients with chronic renal failure who were treated with gabapentin. Gabapentin can be removed by hemodialysis Although hemodialysis has not been performed in the few overdose cases reported, it may be indicated by the patient’s clinical state or in patients with significant renal impairment. If overexposure occurs, call your poison control center at 1-800-222-1222
Monitoring for gabapentin overdose should include observation for signs of acute toxicity such as:
- Ataxia
- Labored breathing
- Ptosis
- Sedation
- Hypoactivity
- Excitation
- Double vision
- Slurred speech
- Drowsiness
- Lethargy
- Diarrhea In cases of overdose, supportive care is recommended, and hemodialysis may be indicated in patients with significant renal impairment or severe clinical symptoms 1.
From the Research
Monitoring for gabapentin overdose should include vital sign assessment, cardiac monitoring, and supportive care, with a focus on respiratory rate and level of consciousness, as respiratory depression is a significant risk, particularly when combined with opioids, as reported in a 2023 study 2.
Key Considerations
- Patients should be observed for at least 4-6 hours after ingestion, with longer monitoring for those with significant symptoms or who took extended-release formulations.
- Specific signs to watch for include drowsiness, dizziness, ataxia, slurred speech, nystagmus, and in severe cases, respiratory depression or coma.
- Laboratory monitoring should include renal function tests, as gabapentin is primarily excreted by the kidneys, and impaired function can prolong its effects.
Treatment Approach
- Treatment is largely supportive, as there is no specific antidote, and includes maintaining airway, breathing, and circulation, with possible activated charcoal administration if the ingestion was recent (within 1-2 hours).
- Hemodialysis may be considered in severe cases with significant renal impairment, as suggested by a 2022 study 3, which found that gabapentin and pregabalin are "dialyzable" for patients with decreased kidney function.
Risk Factors and Considerations
- Gabapentin overdose can be more serious when combined with other central nervous system depressants, and the risk of respiratory depression is increased when gabapentinoids are used with opioids, as reported in a 2017 study 4.
- The drug's mechanism as a GABA analog explains its CNS depressant effects when taken in excessive amounts, and trends in gabapentin exposures reported to U.S. poison centers have shown significant increases in misuse, toxicity, and associated healthcare utilization since 2013, as reported in a 2020 study 5.