To determine the level of levetiracetam in your blood to help establish an individualized dose; to detect toxicity or verify that you are taking the medication as prescribed (compliance); to monitor the impact of a recent health change affecting drug clearance or kidney function
After a stable dose is initially achieved; when indicated to detect low or excessive (potentially toxic) levels; when you have decreased kidney function; sometimes to verify compliance
A blood sample drawn from a vein, typically just before your next dose (trough level)
No special preparation is needed, but timing of sample collection for testing is important.
Levetiracetam is a drug that is used to treat certain seizure disorders (epilepsy) such as: juvenile myoclonic epilepsy, temporal lobe epilepsy, complex partial seizures, myoclonic seizures, refractory seizures, secondarily generalized seizures, simple partial seizures, tonic-clonic seizures. The drug is prescribed as a secondary (adjunctive) treatment in combination with other antiepileptic drugs. This test measures the level of levetiracetam in the blood.
Epilepsy affects the brain's ability to transmit electrical impulses and to regulate nerve activity. During a seizure, a person may experience changes in consciousness, alterations in sight, smell, and taste, and may experience convulsions. The frequency of seizures varies from a single episode, to occasional seizures, to recurrent seizures. Seizures are categorized by the parts of the brain and body that are affected. Levetiracetam is prescribed to help prevent specific types of recurrent seizures.
Levetiracetam is one of several newer second-generation antiepileptic drugs. It has a wider therapeutic range than many existing first-generation seizure medications. That is, the range of concentration in the blood in which the drug is effective without being toxic is broader, making it somewhat safer. It is also associated with fewer severe side effects and does not interact with as many other drugs. Levetiracetam provides a combination of effectiveness and safety that is superior to other treatment choices in many clinical circumstances.
Because levetiracetam has a wider therapeutic range, it does not need to be monitored in the same manner as first-generation antiepileptic drugs. (For further discussion of this, see the article on Therapeutic Drug Monitoring.)
At the start of therapy, doses of levetiracetam may be gradually increased until a standard amount is reached. Once a stable dose is achieved, a blood level may be measured to ensure that it is within the therapeutic range. Since levetiracetam is an adjunct (secondary) medication, the healthcare practitioner will consider the effectiveness of both drugs that are prescribed and adjust them as necessary.
How is the test used?
This test is used to measure the level of levetiracetam in the blood to determine whether the level of drug is within the therapeutic range. Initially, the test may be ordered to help establish the appropriate dose for you. Since the therapeutic range is relatively wide and not well established, your healthcare practitioner will evaluate the effectiveness of the dose in controlling your seizures and whether you have any side effects. Depending on these clinical findings and the results of the blood test, the dose of drug may be adjusted up or down.
Routine periodic monitoring of levetiracetam is usually not required. However, there are circumstances in which it is useful and sometimes necessary to measure blood levels. Some of these include:
- To establish the therapeutic range for an individual (dose individualization); after treatment has started and you have relief from symptoms (no seizures) and suffers no side effects, the level of the drug in the blood is determined. The range around this value is considered therapeutic for you and may be used to evaluate your treatment in the future if your health status or other factors change.
- To verify that your symptoms (seizures or side effects) are not due to too little or too much drug
- To verify that you are taking the medication as prescribed
- To evaluate and adjust the dose as necessary in certain conditions such as:
- Kidney disease—levetiracetam is cleared from the body by the kidneys, so anything that affects kidney function can affect blood levels of the drug.
- A change or addition of other drugs
- Aging—people typically are prescribed seizure medications for their lifetime and, as they age, the amount of drug needed to be effective may change.
- Pregnancy—this condition can temporarily affect drug breakdown (metabolism) and clearance.
When is it ordered?
Levetiracetam tests may occasionally be ordered:
- After you begin taking the drug and a stable dose is achieved
- When your dose is changed
- When you start or stop taking additional medications in order to judge their effects, if any, on the levetiracetam level
- When it appears you are not responding to therapy and have a recurrence of seizures
- When you experience a troublesome level of side effects and/or develop complications; side effects may be seen at any dose but are usually related to higher concentrations. The most common side effects include:
- Adults: sleepiness or drowsiness, weakness or lack of energy, infection and dizziness
- Children: fatigue, aggression, nasal congestion, decreased appetite, and irritability
Tests may be ordered periodically when you have decreased kidney function, an underlying condition that may affect kidney function, and/or significant liver dysfunction.
What does the test result mean?
The therapeutic range for levetiracetam is about 12.0 - 46.0 mcg/mL (mg/L). Levels above 46 mcg/mL are considered potentially toxic. However, ranges vary slightly from laboratory to laboratory, and toxic levels have not been well established.
You and your healthcare practitioners should use the therapeutic ranges and units established by the laboratory that performs your testing. Results should be interpreted in the context of the clinical picture, including evidence of drug effectiveness and/or toxicity.
Within the therapeutic range, most people will respond to the drug without excessive side effects; however, response varies with each individual. Some people will experience seizures at the low end of the therapeutic range, some will experience excessive side effects at the upper end, and some will require dosages outside of the established range for effectiveness and/or freedom from side effects. You should work closely with your healthcare practitioner to find the dose that works the best for you.
In general, if levetiracetam test results are within the therapeutic range (or at an individually established level) and you are not having recurrent seizures and not experiencing significant side effects, then the drug dose is considered adequate.
A level that is outside the therapeutic range may mean you are not taking the drug as prescribed by your healthcare practitioner. This is important to know, as this may put you at increased risk of experiencing symptoms.
How long will I need to be on levetiracetam?
People who have epilepsy will typically take levetiracetam or other medications throughout their lifetime. If levetiracetam ceases to be effective or causes adverse effects, then you may need to be given different drug(s).
What are some serious side effects of levetiracetam?
Very few people taking levetiracetam have serious problems. Tell a doctor straight away if you have a serious side effect, including:
- Flu-like symptoms and a rash on the face, or a rash that spreads or forms blisters – these can be signs of a rare serious skin condition called Stevens-Johnson syndrome.
- Seizures getting worse
- Passing very little urine, feeling tired or confused, or having swollen legs, ankles or feet – these could be signs of kidney problems.
- Signs of serious mental changes, or someone around you notices signs of confusion, sleepiness, loss of memory, forgetfulness, abnormal behavior or uncontrolled movements
- Thoughts of harming or killing yourself – a small number of people taking levetiracetam have had suicidal thoughts
- In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to levetiracetam.
Can I test my levetiracetam level at my healthcare practitioner's office?
What other antiepileptic drugs (AEDs) are there?
There are a broad range of AEDs that have different forms of action available and are used to treat different types of seizures. First-generation AEDs that have been use for a long period of time include phenobarbital (since the early 1900s), phenytoin, carbamazepine, ethosuximide, and valproate (valproic acid). Second-generation AEDs include drugs such as gabapentin, lamotrigine, oxcarbazepine, topiramate, tiagabine, zonisamide and levetiracetam. Newer, third-generation AEDs include drugs such as eslicarbazepine, ezogabine, lacosamide, perampanel, pregabalin, and rufinamide. Some of these are used alone, but most of the newer AEDs are used in combination with other drugs.
Is there anything else I should know?