Indications for: SABRIL
Adjunctive therapy in patients ≥2yrs of age 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. Monotherapy for infantile spasms (IS) in patients 1month–2yrs of age, when the potential benefits outweigh the risk of vision loss.
≥17yrs: initially 500mg twice daily; may be increased weekly by 500mg/day to maintenance 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).
CPS: <2yrs: not established. 2–16yrs: 10–15kg: initially 175mg twice daily; may be increased weekly to maintenance 525mg twice daily. >15–20kg: initially 225mg twice daily (maintenance 650mg twice daily). >20–25kg: initially 250mg twice daily (maintenance 750mg twice daily). 25–60kg: initially 250mg twice daily (maintenance 1g twice daily). >60kg: use adult dosing. 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 daily dose by ⅓ per week for 3 weeks). IS: <1month: not recommended. 1month–2yrs: use oral soln. Initially 50mg/kg/day (given in 2 divided doses); may titrate by 25–50mg/kg/day at 3-day intervals up to max 150mg/kg/day (75mg/kg twice daily). Withdraw gradually (reduce by 25–50mg/kg/day every 3–4 days).
Permanent vision loss.
Be fully familiar with drug’s toxicity before use. 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. Avoid in patients with, or at high risk of other types of irreversible vision loss. Discontinue if no substantial benefit after treating for 3 months (in adults) or 2–4 weeks (in infants); sooner if obvious treatment failure. Increased risk of suicidal thoughts and behavior; monitor for depression, suicidal ideation, unusual changes in mood/behavior. MRI abnormalities in infants. Renal impairment. Use lowest effective dose for shortest duration. Avoid abrupt cessation. Elderly. Pregnancy. Nursing mothers: not recommended.
May antagonize phenytoin. May potentiate clonazepam. Avoid others that can cause visual or ophthalmic dysfunction. Suppresses ALT/AST activity. May cause false (+) amino acid test.
CPS: vision loss (may be severe and permanent), other visual changes (blurring, diplopia, asthenopia), fatigue, somnolence, nystagmus, tremor, memory impairment, weight gain, arthralgia, abnormal coordination, confusion, upper respiratory infection, aggression; headache, dizziness, anemia, peripheral neuropathy, edema. IS: somnolence, bronchitis, ear infection, acute otitis media; neurotoxicity (eg, intramyelinic edema).
To register pregnant patients exposed to vigabatrin call (888) 233-2334. To report ADRs: (800) 455-1141.
Generic Drug Availability:
Tabs—100; Pwd packets—50