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.
