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Am Fam Physician. 2010;82(9):1070

Author disclosure: Nothing to disclose.

Clinical Question

Should persons with epilepsy have routine monitoring of medication blood levels to optimize treatment for preventing seizures?

Evidence-Based Answer

When treating a patient for epilepsy, there is not enough evidence to indicate if optimal seizure control is best obtained by routinely measuring medication levels compared with making adjustments based on the clinical picture. (Strength of Recommendation = C, based on consensus, disease-oriented evidence, usual practice, expert opinion, or case series)

Practice Pointers

Antiepileptic medications are the mainstay of epilepsy treatment. The goal is to maintain a medication dosage with as few seizures and adverse effects as possible. To achieve this, physicians often monitor drug levels in the blood. However, many have questioned if it is better to manage epilepsy by measuring therapeutic drug levels or by titrating medication dosages based on a patient's clinical picture.

In this Cochrane review, the authors did a meta-analysis that examined blinded and unblinded randomized controlled trials of antiepileptic drug monitoring. Participants were of all ages, had various seizure types, and were treated with any antiepileptic monotherapy. The intervention was measurement of antiepileptic drug concentration. Only two studies were identified, and only one prospective randomized study met the inclusion criteria of the review. The other study was excluded because patients were treated with more than one antiepileptic medication.

The study reviewed was an unblinded, prospective, parallel-group design of 180 patients with newly diagnosed, untreated epilepsy. Patients were randomized into a group with drug-level monitoring (intervention) or a group that used the clinical picture alone to alter medication dosage (control). The investigators found no difference in outcomes between the two groups. By 12 months, about 60 percent of patients from both groups achieved remission from seizures, and about one half reported adverse effects.

A position paper published in 2008 by the International League Against Epilepsy Commission on Therapeutic Strategies suggests that routine monitoring of therapeutic drug levels plays a valuable role in epilepsy treatment.1 The paper's recommendations are based on nonrandomized studies and clinical experience, but it acknowledges that there have been no randomized controlled trials indicating the benefit of drug-level monitoring. Although routine monitoring remains the standard of care, it is important for physicians to know that it is not based on good-quality evidence and to watch for additional studies.

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