Broad-spectrum Anti-seizure Meds

Lamotrigine

Blocks Na channels and lowers glutamate.

Also used for bipolar disorder.

Dosing:

• Initial: 25 mg daily (weeks 1 and 2)

Boxed Warnings: SJS/TEN

Warnings: DRESS

SE: alopecia, somnolence, tremor, ataxia

• Supplement w/ biotin, selenium, and zinc for alopecia.

Notes:

• If d/c for > 5 half-lives, restart initial dosing.

• Estrogen containing contraceptives can lower lamotrigine levels so increase maintenance doses.

Topiramate

Blocks Na channel.

Also used for migraine ppx.

Warnings: metabolic acidosis, oligohidrosis (reduced perspiration), nephrolithiasis (kidney stones), angle-closure glaucoma, hyperammonemia, visual problems, fetal harm

SE: somnolence, difficulty with concentration/memory/attention, weight loss, anorexia

Monitor: bicarbonate and intraocular pressure

Notes:

• Lamotrigine can lower drug levels.

• Topiramate can reduce oral contraceptive effectives so use non-hormonal contraception.

• Topiramate can decrease INR in pts with warfarin.

Levetiracetam

Inhibits vesicle fusion by binding SV2A proteins.

Dosing: IV:PO ratio is 1:1

Warnings: psychiatric symptoms like psychotic sx, somnolence, fatigue, aggression

SE: somnolence, weakness, asthenia

*No significant drug interactions.

Valproate

Blocks Na channel and increases GABA.

Also used for bipolar disease and migraine ppx.

Dosing: Initial dose of 10-15 mg/kg/day with a therapeutic range of 50-100 mcg/mL (total level)

Boxed Warnings: hepatic failure, pancreatitis, and fetal harm (neural tube defects and lower IQ scores)

Warnings: hyperammonia (tx: carnitine in symptomatic adults only), dose-related thrombocytopenia, DRESS

SE: alopecia, N/V, weight changes ( gain > loss), somnolence, tremor

Monitor: LFTs (baseline and frequently in first 6 months), CBC w/ differential (especially plt)

Notes:

• Carbapenem and estrogen-containing contraceptives lower drug levels.

• Concurrent use with topiramate = higher risk for hyperammonia.

• Valproate can increase levels of lamotrigine, phenobarbital, phenytoin, warfarin, and zidovudine.