Antiepileptics

Antiseizure Medications (ASMs) – Quick Reference

• Dropdowns by class • Concise dosing & adjustments • Minimal inline styles.
• For clinical use, confirm in a trusted reference (e.g., labels/UpToDate/lexicomp) and patient specifics.

Voltage-Gated Sodium Channel Blockers

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Eslicarbazepine (Aptiom)	800–1600 mg PO daily (once daily). Titrate by 400–600 mg weekly.	CrCl <50 mL/min ↓ dose; severe hepatic impairment: caution (limited data).	↓ Hormonal contraceptives; additive hyponatremia with oxcarb/carb; induces UGT/CYP3A.
Carbamazepine (Tegretol)	800–1200 mg/day PO divided (ER often BID). Target by levels/response.	Hepatic disease: caution/avoid severe; autoinduction; no renal adj. typically.	Strong CYP3A4 inducer (↓ many drugs incl. OCPs, DOACs); ↑ by inhibitors (macrolides, azoles). HLA-B*1502 risk (SJS/TEN).
Oxcarbazepine (Trileptal)	600–2400 mg/day PO divided BID (ER once daily).	CrCl <30 mL/min: start 300 mg/day, slow titration. Hepatic: no adjustment (mild–mod).	↓ OCPs; less enzyme induction vs CBZ; hyponatremia common—monitor Na.
Phenytoin / Fosphenytoin	Phenytoin 300–400 mg/day PO (qHS or divided); individualized by levels (nonlinear).	Hypoalbuminemia/renal failure alter free levels; hepatic disease ↓ clearance.	CYP inducer; many DDIs (warfarin, OCPs, azoles). Monitor levels; long-term AEs.
Lamotrigine (Lamictal)	Maintenance ~100–400 mg/day (divided or once daily ER); titration depends on VPA/inducers.	Hepatic impairment: ↓ dose; renal failure: consider ↓ (metabolites).	↑ by valproate (halve/quarter dose); ↓ by enzyme inducers; rash risk—slow titration.
Lacosamide (Vimpat)	200–400 mg/day PO/IV divided BID (or once-daily ER).	CrCl ≤30 mL/min or mod–severe hepatic: max 300 mg/day; avoid severe hepatic.	PR prolongation/arrhythmias; additive with other Na+ blockers.
Rufinamide (Banzel)	800–3200 mg/day divided BID (take with food).	Hepatic impairment: ↓ dose; no renal adj. usually.	↓ by enzyme inducers; may ↓ OCPs; QT shortening (caution in short-QT).

Calcium Channel Modulators

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Ethosuximide (Zarontin)	500–1500 mg/day PO divided (q12h typical).	Hepatic & renal clearance: caution/monitor in impairment.	Few DDIs; GI upset common; first-line absence seizures.
Zonisamide (Zonegran)	200–400 mg/day PO (once daily or divided); max 600 mg/day.	Avoid severe renal (CrCl <50) or severe hepatic impairment.	Sulfonamide; CA inhibition → stones, metabolic acidosis; oligohidrosis/heat risk.
Gabapentin (Neurontin)	900–3600 mg/day PO divided TID (titrate by response).	Renal: dose by CrCl; no hepatic adj.	Minimal DDIs; sedation/ataxia; absorption saturable—TID dosing.
Pregabalin (Lyrica)	150–600 mg/day PO divided BID/TID.	Renal: dose by CrCl; no hepatic adj.	Edema/weight gain; euphoria/misuse potential; minimal DDIs.

GABAergic Agents

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Benzodiazepines (e.g., Clobazam)	Clobazam 10–40 mg/day (divided). (Diazepam/lorazepam/midazolam: per acute/status protocols.)	Hepatic dysfunction: ↓ dose; elderly: ↓ dose.	Additive CNS depression (opioids, alcohol); tolerance/dependence; CYP2C19 interactions (clobazam).
Phenobarbital / Primidone	Phenobarbital 60–200 mg/day (qHS common); primidone 750–1500 mg/day divided.	Hepatic impairment: avoid/severe caution; renal: adjust (PB is renally cleared partly).	Strong enzyme inducer; sedation/cognitive effects; bone health issues.
Tiagabine (Gabitril)	16–56 mg/day divided (BID–QID), titrate slowly.	Hepatic impairment: ↓ dose; no renal adj.	Enzyme inducers may ↓ levels; risk of non-epileptic seizures in nonepileptics.
Vigabatrin (Sabril)	1000–3000 mg/day divided BID.	Renal: ↓ dose; no hepatic adj.	Irreversible GABA-T inhibitor; permanent visual field loss risk (REMS).

Glutamate Receptor Antagonists / Modulators

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Perampanel (Fycompa)	4–12 mg PO nightly (titrate by 2 mg weekly).	Mod hepatic: max 8 mg; avoid severe hepatic; avoid severe renal.	Enzyme inducers ↓ levels; behavioral AEs (aggression, irritability).
Felbamate (Felbatol)	1200–3600 mg/day divided TID–QID.	Avoid in hepatic dysfunction; monitor LFTs; adjust in renal impairment.	Aplastic anemia/hepatotoxicity risk; CYP interactions (↑ phenytoin/VPA; ↓ CBZ).
Topiramate (Topamax)	100–400 mg/day divided BID (or once-daily ER).	CrCl <70: ↓ dose/slow titration; hepatic impairment: caution.	↓ OCPs ≥200 mg/day; CA inhibition → stones, metabolic acidosis; weight loss/cognitive effects.

Synaptic Vesicle Protein 2A (SV2A) Ligands

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Levetiracetam (Keppra)	1000–3000 mg/day divided BID (XR once daily).	Renal: dose by CrCl; no hepatic adj. typically.	Minimal DDIs; behavioral changes in some (irritability).
Brivaracetam (Briviact)	50–200 mg/day divided BID (or once-daily XR).	Severe hepatic impairment: ↓ dose; no renal adj. (non-dialyzable largely).	Fewer behavioral AEs vs LEV; minor CYP2C19 interactions.

Carbonic Anhydrase Inhibitors

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Acetazolamide (Diamox)	250–1000 mg/day divided BID–QID (intermittent use typical for epilepsy).	Renal: ↓ dose/avoid severe; hepatic disease: avoid (risk of encephalopathy).	Metabolic acidosis, hypokalemia; caution with salicylates; sulfonamide cross-reactivity.
Topiramate (Topamax)	See above (100–400 mg/day; ER once daily possible).	CrCl <70: ↓ dose; hepatic: caution.	↓ OCPs ≥200 mg/day; stones, acidosis; cognitive effects, weight loss.
Zonisamide (Zonegran)	See above (200–400 mg/day; max 600 mg/day).	Avoid severe renal/hepatic impairment.	Stones, acidosis; oligohidrosis/heat; sulfonamide allergy caution.

Broad / Mixed Mechanisms

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Valproate / Divalproex (Depakote)	500–3000 mg/day divided BID/TID or ER daily; target by levels/response.	Hepatic disease: contraindicated/severe caution; thrombocytopenia risk; renal: no routine adj.	↑ lamotrigine levels (halve/quarter LTG); teratogenic; weight gain, tremor; UGT inhibitor.
Topiramate (Topamax)	100–400 mg/day (see above).	CrCl <70 ↓; hepatic caution.	↓ OCPs; CA inhibition; migraine prevention dual use.
Zonisamide (Zonegran)	200–400 mg/day (see above).	Avoid severe renal/hepatic impairment.	Mixed mechanism; heat/stones/acidosis cautions.
Lamotrigine (Lamictal)	100–400 mg/day (see above; titration crucial).	↓ dose w/ hepatic impairment; consider ↓ in renal failure.	DDI with VPA (↑), inducers (↓); rash risk—educate patient.
Cenobamate (Xcopri)	Maintenance 200 mg/day (100–400 mg/day range) after very slow titration.	Hepatic impairment: ↓ dose; renal impairment: caution/↓ dose.	↑ GABAA, ↓ persistent Na+ current; DRESS—slow titration; induces CYP3A4, inhibits CYP2C19 (↑ phenytoin/phenobarb).

Other / Unique Mechanisms

Drug (Brand)	Typical Adult Dose Range	Renal/Hepatic Adjustments	Key Interactions / Notes
Cannabidiol (Epidiolex)	Up to 10–20 mg/kg/day divided BID (FDA-labeled syndromes).	Hepatic impairment: ↓ dose; monitor LFTs.	↑ by CYP2C19/3A inhibitors; ↑ clobazam metabolite (sedation); monitor transaminases esp. w/ VPA.
Everolimus (Afinitor)	TSC-associated seizures: 5–10 mg/m²/day (target trough 5–15 ng/mL).	Hepatic impairment: ↓ dose; renal: none typically.	CYP3A4/P-gp substrate—many DDIs (azoles/macrolides); stomatitis, hyperlipidemia, immunosuppression.

Quick ID: Eslicarbazepine = Na⁺ blocker (slow inactivation). Zonisamide = mixed (Na⁺ + T-type Ca²⁺ + carbonic anhydrase inhibition).
Always consider formulation (IR vs ER), titration speed, age, comorbidities, pregnancy, enzyme-inducer status, and seizure type.