Description
Overview:
Carbamazepine (sold under brand names like Tegretol or Zeptol) is a widely used medication for treating epilepsy (seizures), trigeminal neuralgia (nerve pain), and bipolar disorder. Because the body processes this drug at variable rates, and because it has a “narrow therapeutic index” (the difference between a helpful dose and a toxic dose is small), regular monitoring is critical.
Clinical Significance:
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Therapeutic Drug Monitoring (TDM): The goal is to keep blood levels between 4 and 12 mcg/mL.
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Preventing Toxicity: Levels that are too high can cause dizziness, unsteadiness, double vision, and confusion.
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Ensuring Efficacy: Levels that are too low may result in the recurrence of seizures or nerve pain.
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Drug Interactions: Carbamazepine interacts with many other medications, which can suddenly alter its concentration in your blood.
When is this test recommended?
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Routine Monitoring: Regularly to ensure the dosage remains correct over time.
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Suspected Toxicity: If symptoms like nausea, dizziness, or blurred vision occur.
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Lack of Control: If seizures return despite taking the medication.
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New Medications: When starting or stopping other drugs that might interfere with Carbamazepine.
Sample Requirements:
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Specimen: Serum.
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Container: Red Top (Plain) Tube is preferred. Note: Gel tubes (SST) are sometimes avoided for drug levels as the gel can absorb the drug, lowering the result. Check specific lab protocol.
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Timing (Trough Level): The sample should ideally be drawn just before your next scheduled dose (trough level) to measure the lowest concentration in the blood.
