Barbiturates like phenobarbital can be addictive because of their sedative-hypnotic and anti-anxiety effects, but psychological dependence (a psychological craving after long-term use) is rare in people taking phenobarbital to treat epilepsy.

Physical dependence, on the other hand, is common. With physical dependence, a withdrawal syndrome occurs if the medication is stopped suddenly or if the dosage is sharply reduced. These withdrawal symptoms may include:

• anxiety
• increased heart rate
• sweating
• confusion
• seizures
• death (very rarely)

It is therefore important to taper patients off phenobarbital gradually to avoid withdrawal symptoms.

Women who may become pregnant should be aware that studies have suggested a connection between phenobarbital and a higher-than-expected incidence of birth defects. There also is a danger to the baby from withdrawal symptoms if the mother has taken phenobarbital in the last few months of pregnancy, since barbiturates cross the placenta into the baby.

In general, it is wise for patients to avoid alcohol while taking phenobarbital.

On July 10, 2008, an advisory panel was convened by the Food and Drug Administration (FDA) to review data that the FDA had previously collected from drug studies showing an association between many of the antiepileptic drugs (AEDs) and suicidal ideation and behavior, which together are called suicidality. According to the FDA’s Alert, among the patients with epilepsy in these drug studies, 1 out of 1000 people taking the placebo (inactive substance) showed suicidality compared to approximately 3.5 out of 1000 people who took an AED. The FDA advisory panel voted to accept the FDA's data at its meeting on July 10. The FDA has provided the following information for patients, family members, and caregivers at www.fda.gov/cder/drug/InfoSheets/HCP/antiepilepticsHCP.htm.

• Taking antiepileptic medicines may increase the risk of having suicidal thoughts or actions;
• Do not make any changes to the medication regimen without first talking with the responsible healthcare professional;
• Pay close attention to any day-to-day changes in mood, behavior and actions. These changes can happen very quickly so it is important to be mindful of any sudden differences.
• Be aware of common warning signs that might be a signal for risk of suicide. Some of these are:
  • Talking or thinking about wanting to hurt yourself or end your life
  • Withdrawing from friends and family
  • Becoming depressed or having your depression get worse
  • Becoming preoccupied with death and dying
  • Giving away prized possessions

We again urge patients and families to contact their doctor before stopping an epilepsy medication because this may possibly lead to seizures and worsening of mood.

Reviewed July 2008 by Steven C. Schachter, MD, epilepsy.com Editorial Board.