Adjunctive therapy in adult patients with refractory complex partial seizures (CPS) who have inadequately responded to several alternative treatments and for whom the potential benefits outweigh the risk of vision loss. Not a first line agent for CPS.
>16yrs: Use tabs. Initially 500mg twice daily; titrate if needed by 500mg per week to 1.5g twice daily. CrCl >50–80mL/min: reduce dose by 25%; CrCl >30–50mL/min: reduce dose by 50%; CrCl >10–<30mL/min: reduce dose by 75%. Reevaluate periodically. Withdraw gradually (reduce by 1g/day at weekly intervals).
<10yrs: not recommended. 10–16yrs: 25–60kg: initially 250mg twice daily; titrate per week to 1g twice daily. >60kg: use adult dosing. Withdraw gradually (reduce daily dose by ⅓ per week for 3 weeks).
Monitor vision, including visual acuity and dilated indirect ophthalmoscopy, and visual fields, at baseline (within 4 weeks) and every 3 months, and for 3–6 months after discontinuing; risk of vision loss increases as dose and cumulative exposure increased. Discontinue if no substantial benefit after treating for 3 months (in adults) or 2–4 weeks (in infants); sooner if obvious treatment failure. Monitor for depression, suicidal ideation, changes in mood/behavior. Avoid abrupt cessation. Elderly. Pregnancy (Cat.C). Nursing mothers: not recommended.
May antagonize phenytoin. May potentiate clonazepam. Avoid others that can cause visual or ophthalmic dysfunction. May interfere with liver function tests (eg, ALT), others (see literature).
RCPS: vision loss (may be severe and permanent), other visual changes (blurring, diplopia, asthenopia), headache, nystagmus, anemia, somnolence, fatigue, peripheral neuropathy, weight gain, edema, arthralgia, dizziness, tremor, CNS/neurological effects, upper respiratory infection, rash; abnormal MRI signal changes in infants. IS: bronchitis, ear infection, acute otitis media.
Available only through restricted distribution program. To register call (888) 45-SHARE. Encourage pregnant patients exposed to vigabatrin to call (888) 233-2334. To report ADRs: (800) 455-1141.
Tabs—100; Pwd packets—50