From the Guidelines
When monitoring patients on oxcarbazepine, it is crucial to check complete blood counts (CBC), sodium levels, and liver function tests, as oxcarbazepine can cause hyponatremia and CBC abnormalities, including leukopenia, agranulocytosis, aplastic anemia, and thrombocytopenia, as reported in a study published in 2020 1. The most significant electrolyte abnormality associated with oxcarbazepine is hyponatremia, which occurs in about 2.5% of patients. Regarding CBC abnormalities, oxcarbazepine can occasionally cause leukopenia, with rare cases of agranulocytosis and aplastic anemia, as well as thrombocytopenia. These hematologic effects are less common than with carbamazepine but still warrant monitoring, especially during the first few months of treatment. Some key points to consider when monitoring patients on oxcarbazepine include:
- Baseline CBC, electrolytes, and liver function tests should be obtained before starting therapy, with follow-up testing at regular intervals, particularly during the first 3 months.
- Patients should be educated about symptoms of blood disorders, such as fever, sore throat, mouth ulcers, and easy bruising, as well as hyponatremia, which can cause headache, confusion, and nausea.
- Oxcarbazepine's effects on blood counts are due to its impact on bone marrow function, while hyponatremia results from enhanced renal water reabsorption similar to inappropriate ADH secretion.
- More frequent monitoring is recommended in elderly patients and those with renal impairment, as they have a higher risk of adverse effects, as noted in various studies, including one published in 2011 1. It is essential to prioritize the patient's morbidity, mortality, and quality of life when monitoring them on oxcarbazepine, and to adjust the monitoring schedule accordingly, based on the most recent and highest quality evidence available, such as the study published in 2020 1.
From the FDA Drug Label
Laboratory Abnormality: ... hypokalemia, ... Hematologic and Lymphatic System: thrombocytopenia. Laboratory Tests Serum sodium levels below 125 mmol/L have been observed in patients treated with Oxcarbazepine Hematologic and Lymphatic Systems: aplastic anemia
Monitoring for patients on oxcarbazepine should include:
- Serum sodium levels, as hyponatremia can occur
- Complete Blood Count (CBC), as thrombocytopenia and aplastic anemia have been reported
- Monitoring for signs of hypokalemia may also be necessary 2 2
From the Research
Monitoring Parameters for Oxcarbazepine
When a patient is on oxcarbazepine, several parameters should be monitored, including:
- Serum sodium levels, as hyponatremia (serum sodium <125 mmol/l) can develop gradually during the first months of oxcarbazepine therapy in approximately 3% of patients with a previously normal serum sodium 3
- Complete blood count (CBC) profiles, as oxcarbazepine-induced leukopenia is not rare and may result in pancytopenia 4
- Hematologic test results, although oxcarbazepine does not appear to have any clinically notable effects on other safety parameters such as renal and liver function or haematological test results 3
CBC Abnormalities
Oxcarbazepine can cause CBC abnormalities, including:
- Leukopenia, which can develop in 5.4% of patients 4
- Pancytopenia, which can develop in 1.0% of patients 4
- These abnormalities can occur at any time during treatment, but are more frequent in males than in females 4
Comparison with Carbamazepine
Carbamazepine, a related antiepileptic drug, can also cause hematologic effects, including:
- Agranulocytosis, thrombocytopenia, leukopenia, aplastic anemia, eosinophilia, or pancytopenia 5, 6, 7
- The incidence of serious side effects from carbamazepine pharmacotherapy is low, and their exact mechanism of action is still unknown 6
- Monitoring of hematologic parameters is recommended for patients on carbamazepine, especially during the first three months of treatment 5