MKSAP Quiz: Maintenance of epilepsy drug
MKSAP Quiz: Maintenance of epilepsy drug
A 65-year-old woman comes to the office for her annual examination. She reports that she had a tonic-clonic seizure at age 24 years after the birth of her daughter but has been seizure-free on phenytoin since that time. The patient also has osteoporosis, diagnosed after a screening bone density scan. Current medications include phenytoin, alendronate, calcium, and vitamin D.
Physical examination findings are normal.
Which of the following is the most appropriate next step in management?
A. Check the serum phenytoin level
B. Continue the current dosage of phenytoin
C. Discontinue the phenytoin in a tapered fashion
D. Substitute lamotrigine for the phenytoin
MKSAP Answer and Critique
The correct answer is C) Discontinue the phenytoin in a tapered fashion. This item is available to online to MKSAP 15 subscribers as item 74 in Neurology.
Phenytoin therapy should be discontinued in this patient in a tapered fashion. Although lifelong antiepileptic drug therapy is required for some patients and for some types of epilepsy, this is by no means always the case. As a general rule, discontinuation of antiepileptic drugs should be considered for patients who have been seizure free for 2 or more years. Medications should not be withdrawn in patients with epilepsy syndromes known to be lifelong, with underlying structural brain lesions, with symptomatic neurologic disorders, or (in most cases) with a history of medically refractory seizures. The risk of recurrent seizure when the patient is no longer taking the medication must always be balanced against the risks associated with continued antiepileptic drug treatment. Unfortunately, too many patients are treated unnecessarily for years because of the common misconception that antiepileptic drug therapy can never be safely discontinued. This patient has been seizure free for more than 40 years; in fact, the decision to initiate therapy was questionable because she only had a single event. Now she has osteoporosis, a condition that can be worsened by continued exposure to phenytoin. Therefore, the most appropriate next step in management is to gradually withdraw the medication.
Because the phenytoin will be withdrawn, there is no need to determine a blood level prior to tapering the medication; the results will not affect when or how the medication will be tapered. This patient has been seizure free for more than 2 years and thus meets the criteria for careful withdrawal of the antiepileptic medication. There is no indication to substitute lamotrigine for the phenytoin or to continue the phenytoin.
Key Point
- Patients on antiepileptic medication who have been seizure free for 2 years should be considered for medication withdrawal.