Principles of Medication Therapy
Most epilepsy specialists use several principles to govern the treatment of seizures with antiepileptic medications.
The first principle is to decide whether to treat. Certain simple partial seizures with minor sensory, motor or thought activity might not require treatment. Even absence seizures or seizures of a partial complex nature might not require treatment, provided that they did not bother the patient, cause falls or injuries, and the patient did not wish to drive or work in potentially injurious conditions. A single seizure might not require treatment since about 50% of people who have a single idiopathic generalized tonic-clonic seizure, with negative EEG, MRI and blood tests, will not have another seizure. By the second seizure, most epilepsy specialists would initiate treatment.
Antiepileptic therapy is not necessarily for life, but it can be. Under some conditions, medications safely can be tapered. This is particularly true if a patient has been seizure-free for at least 2 - 5 years, has no underlying structural lesion, does not have a genetic condition such as juvenile myoclonic epilepsy predisposing to ongoing seizures, has not had problems with status epilepticus, and has no seizure activity on a routine EEG. In these circumstances, there is a two-in-three chance of being able to withdraw seizure medicines. Of course, the other side of this risk is a one-in-three chance of having a seizure within the three years after withdrawing medicine. Some patients find this risk unacceptably high. Physicians advise most patients not to drive for three months during a taper of all seizure medicine.
The clinician should simplify the medication regimen. Complex regimens are not followed by most patients. A drug schedule of one dose per day is more often followed correctly than is a twice, three or four times a day schedule. Monotherapy (one drug) is simpler than polypharmacy (many drugs) and monotherapy avoids drug interactions. About 80 percent of people with epilepsy can be treated with monotherapy. However, tapering to monotherapy can be difficult, because of transient flare-up of seizures.
Some drugs need to be built up slowly to avoid side effects. Carbamazepine, valproic acid, lamotrigine, primidone, topiramate, tiagabine, vigabatrin all have to be initiated over a period of a few weeks. In contrast, phenytoin, phenobarbital, gabapentin, and levetiracetam can be initiated at a therapeutic dose. Schedules must be written out in advance. Patients should have phone access to the medical team during the dose-titration period to deal with emergence of side effects.
Switching from one medication to another can be difficult. If the second medicine has to be added slowly, then it usually is not advisable to taper the first medication until the second one is at a therapeutic dose. Otherwise, the patient could have seizures while being inadequately protected during the switch. Toxicity is to be expected during the time of medication overlap. Patients need to be warned to expect a temporary period of more side effects and possible withdrawal seizures.
Serum blood levels can be useful guides in treatment of antiepileptic medications, but they are probably over-used. If a patient is doing well without seizures and medication toxicity, then serum levels may be superfluous. Particularly in cases of polypharmacy, serum levels may help determine which drug is causing toxicity.