In some cases, to determine the concentration of levetiracetam in the blood to establish an individualised dose; to detect toxicity or verify that a person is taking the medication as prescribed (compliance /adherence); to monitor changes that may affect drug clearance and/or kidney function.
In some cases, at the start of treatment when establishing dosage; when indicated to detect low or excessive (potentially toxic) concentrations; when a person has decreased kidney function; occasionally to verify compliance /adherence.
A blood sample taken from a vein in your arm.
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Levetiracetam is a drug that is used to treat certain seizure disorders (also called epilepsy). It is prescribed either as primary therapy or as an adjunctive (secondary) treatment in combination with other antiepileptic drugs. This test measures the amount 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 categorised 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. Since it is relatively new, however, it has less of a ‘use history’ – its long-term safety and efficacy and its appropriate therapeutic range are less well established.
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.) However, there are circumstances in which it is useful and sometimes necessary to measure blood levels. Some of these include:
To establish the range that is therapeutic for an individual; after treatment has started and the individual has relief from symptoms (no seizures) and suffers no side effects, the concentration of the drug in the blood is determined. The range around this value is considered therapeutic for the person and may be used to evaluate their treatment in the future if their health status or other factors change.
To verify that a person's symptoms (seizures or side effects) are not due to too little or too much drug; to verify that a person is 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 life and, as they age, the amount of drug needed to be effective may change.
Pregnancy—this condition can temporarily affect drug metabolism and clearance.
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 sometimes be measured to ensure that it is within the therapeutic range. If levetiracetam is being used as an adjunctive (secondary) medication, the doctor will also consider the effectiveness of other drugs that are prescribed and may adjust them as necessary.