Magazine article Clinical Psychiatry News

Drug Update: Chronic Seizures in Adults

Magazine article Clinical Psychiatry News

Drug Update: Chronic Seizures in Adults

Article excerpt

In adults, partial and generalized seizures are by far the most common forms of epilepsy Choosing among the widening array of antiepileptic drugs for adult patients with these seizures requires balancing many factors: efficacy, adverse effects, drug interactions, patient compliance, and affordability Older drugs tend to be inferior to newer drugs except for affordability.

Older agents tend to have more side effects, such as drowsiness and impaired cognition, but they can be quite effective in patients who tolerate them. Older drugs also tend to be much cheaper. A regimen based on phenobarbital costs pennies a day, while the daily cost for some newer drugs can be more than $7.

Standard, initial treatment is typically monotherapy with an older drug; most neurologists favor carbamazepine for the types of seizures that adults usually have. A newer, related drug, oxcarbazepine, is supplanting carbamazepine because it seems somewhat safer. If seizures are not controlled at a tolerable dosage, monotherapy with a different agent is then tried. Usually only if this also fails, is combination therapy considered.

The newer agents are indicated for add-on therapy of partial seizures, as well as for primary generalized epilepsy among patients who have weight gain or other difficulties with an older drug. Also consider newer agents for initial therapy of women on OCs because they are less likely to interfere with the contraceptive. Elderly and medically complicated patients may also fare better with a newer agent because these are generally better tolerated and have fewer drug interactions.

Special concerns exist for women with childbearing potential. The overall rate of birth defects among healthy women is about 2%-3%. Among women with a history of epilepsy who are not currently having seizures or taking medications, this rate increases to about 3%-5%; genetic factors appear to be involved. For women taking certain antiepileptic drugs, the rate may rise to about 10%. Phenobarbital, valproic acid, carbamazepine, and phenytoin are known to pose risks to fetal development. Ongoing pregnancy registries are now attempting to clarify the safety issues of the other drugs. Folic acid supplementation is becoming routine to help protect against potential risks to fetal development.

OLDER AGENTS

Drug           Dose         Cost/Dose

Carbamazepine  600-1,200    $2.36 (Carbatrol,
 (Carbatrol,   mg/day       400 mg b.i.d.);
 Tegretol-XR)               $2.04
                            (Tegretol-XR,
                            400 mg b.i.d.)







valproic acid  1,750-3,000  $4.96
               mg/day       (1,000 mg
                            b.i.d.)









phenytoin      200-400      $0.93
 sodium        mg\day       (300 mg/day)
 extended















phenobarbital  100 mg/day   $0.06










Drug           Comment

Carbamazepine  Consensus first choice for partial and generalized
 (Carbatrol,   seizures for most patients. Available as a
 Tegretol-XR)  long-acting formulation that allows b.i.d. dosing.
               Regular blood monitoring required because of risk
               of aplastic anemia. A newer, related drug,
               oxcarbazepine (Trileptal), is gaining in
               popularity because it has no potential for causing
               aplastic anemia. Avoid carbamazepine in women on
               OCs. Long-term use can cause osteopenia and
               fractures; supplementation with calcium and
               vitamin D recommended.

valproic acid  Wide spectrum of action; used for partial abasence
               (petit mal), myoclonic, and tonic-clonic seizures
               (none of which are common in adults). Nausea and
               vomiting are the most commonly reported side
               effects; considerable weight gain--up to 20-30
               pounds--can occur. Menstrual irregularities and
               polycystic ovary syndrome have been reported in
               young women. … 
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