Description
Why It’s Done
This test is used to:
• Monitor drug levels in patients on long-term phenobarbital therapy.
• Help doctors adjust the dosage for optimal control of seizures.
• Check for drug toxicity, especially if side effects such as drowsiness, confusion, or difficulty breathing occur.
• Confirm medication adherence in individuals with uncontrolled seizures.
Preparation
• No fasting is required.
• Trough level testing (just before the next scheduled dose) is often preferred for consistency.
• Inform your doctor or lab if:
o You’re taking other medications (as interactions may affect phenobarbital levels).
o There has been any recent change in dosage.
• A blood sample is collected from a vein in your arm.
