THERAPEUTICS

Brands

• Zarontin

Generic?

• Yes

Class

• Antiepileptic drug (AED)

Commonly Prescribed for

(FDA approved in bold)

• Absence (petit mal) epilepsy

• Intermittent explosive disorder

How the Drug Works

• There are multiple proposed mechanisms of action, and it is uncertain which of these give the drug its effectiveness

• Blocks or modulates low-voltage T-type calcium channels

• Modulates sodium channel function

• May alter glutamate or GABA levels

• Proven to suppress paroxysmal 3-hertz spike and slow wave discharges on EEG

How Long Until It Works

• Seizures: should decrease by 2 weeks

If It Works

• Seizures: goal is the remission of seizures. Continue as long as effective and well tolerated. Consider tapering and slowly stopping after 2 years without seizures, depending on the type of epilepsy

If It Doesn't Work

• Increase to highest tolerated dose

• Epilepsy: consider changing to another agent, adding a second agent, using a medical device, or a referral for epilepsy surgery evaluation. When adding a second agent, keep drug interactions in mind

Best Augmenting Combos for Partial Response or Treatment-Resistance

• Epilepsy: often used in combination when more than one type of epilepsy exists. Effective in combination with valproate or lamotrigine for absence seizures but this can cause interactions and change levels of drug

Tests

• CBC, urinalysis, and liver function tests at baseline and on a periodic basis

ADVERSE EFFECTS (AEs)

How the Drug Causes AEs

• CNS AEs are probably caused by effects on calcium or sodium channels

Notable AEs

• Sedation, ataxia, dizziness, headache, blurred vision, insomnia

• Nausea, vomiting, cramps, anorexia, abdominal pain, constipation

• Increased urinary frequency, muscle weakness, periorbital edema, pruritus

Life-Threatening or Dangerous AEs

• Rare blood dyscrasias including leukopenia, eosinophilia, pancytopenia

• Rare cases of systemic lupus erythematosus

• Severe dermatological manifestations including Stevens-Johnson syndrome, erythema multiforme

• Suicidal behavior and ideation

Weight Gain

• Unusual