From the FDA Drug Label
Felbamate tablets can cause serious side effects, including:
- Felbamate tablets may cause serious blood problems that may be life-threatening Call your healthcare provider right away if you have any of the following symptoms: Fever, sore throat or other infections that come and go or do not go away Frequent infections or an infection that does not go away Easy bruising Red or purple spots on your body Bleeding gums or nose bleeds Severe fatigue or weakness
- Liver problems that may be life-threatening Call your healthcare provider right away if you have any of these symptoms: yellowing of your skin or the whites of your eyes (jaundice) dark urine nausea or vomiting loss of appetite pain on the right side of your stomach (abdomen)
The symptoms of felbamate toxicity include:
- Blood problems: fever, sore throat, frequent infections, easy bruising, red or purple spots on the body, bleeding gums or nose bleeds, severe fatigue or weakness
- Liver problems: yellowing of the skin or eyes, dark urine, nausea or vomiting, loss of appetite, pain on the right side of the stomach 1
From the Research
Felbamate toxicity symptoms include both common side effects and serious adverse reactions, and due to its potentially life-threatening effects, it is typically reserved as a last-line therapy for refractory epilepsy, particularly Lennox-Gastaut syndrome. Common symptoms include insomnia, headache, nausea, vomiting, anorexia, weight loss, dizziness, and fatigue 2. More concerning toxicity manifestations include aplastic anemia (presenting with fatigue, pallor, increased infections, and bleeding), hepatotoxicity (with jaundice, abdominal pain, nausea, vomiting, and elevated liver enzymes), and serious skin reactions 3, 4. Neurological symptoms may include tremor, ataxia, and mood changes. Felbamate can also cause metabolic acidosis in some patients.
Key Considerations
- The drug's toxicity is thought to be related to its metabolism to reactive intermediates that can bind to cellular proteins and cause immune-mediated reactions 5.
- If toxicity is suspected, the drug should be discontinued immediately and appropriate supportive care provided.
- Regular monitoring of complete blood counts and liver function tests is essential for patients taking felbamate 2, 4.
- Patients must be educated in the likely prodromal symptoms of potential marrow/liver toxicity 2.
- The use of felbamate should be restricted to patients with medically refractory epilepsy, and its use should be carefully evaluated before starting treatment 3, 5.
Monitoring and Precautions
- Liver function tests and complete blood count (CBC) should be conducted prior to therapy and at clinically rational intervals 2.
- Plasma assays of other antiepileptics may also be necessary due to potential interactions with felbamate 4.
- Close clinical monitoring is necessary to ensure the tolerability of the entire treatment regimen 4.