Epilepsy Drug Summary

Last updated: 02 June 2025
Reviewed by

Anticonvulsants

Drug Dosage Remarks
Barbiturates
Phenobarbital (Phenobarbitone) 30 mg PO 12 hourly or
30-350 mg/day in divided doses or
120-250 mg PO 24 hourly at night or 2-3 mg/kg PO 24 hourly at night
Management of acute seizures and status epilepticus:
10-20 mg/kg IV at a rate of ≤100 mg/min
May administer additional 5-10 mg/kg IV after 10 minutes if needed
Max dose: 1,000 mg/dose		 Adverse Reactions
  • CNS effects (sedation which usually decreases after repeated administration, subtle mood changes, impairment of cognition and memory, depression)
  • Rarely, hypersensitivity, rashes, Stevens-Johnson syndrome, erythema multiforme; Hepatitis and hepatic failure have occurred
  • May interfere with vitamin D and folate metabolism which may lead to osteomalacia
  • Prolonged administration may result in folate deficiency, rarely megaloblastic anemia
  • Nystagmus, respiratory depression or ataxia may occur at high doses
  • Overdose may result in severe respiratory depression, coma, CV depression, hypotension, shock and renal failure
Special Instructions
  • Avoid in patients with porphyria
  • Use with caution in patients with respiratory, liver or renal dysfunction
    • Contraindicated if the impairment is severe
  • Use with caution in patients with depression or suicidal tendencies, history of drug abuse, acute or chronic pain
  • Adjust dose based on individual response to control seizures
  • Clinical authorities recommend that patients taking Phenobarbital should be supplemented with folate
  • Monitoring Phenobarbital plasma concentration may aid in assessing control
    • Therapeutic level: 86-172 micromol/L (20-40 mcg/mL)
  • Monitor CBC, liver function and mental status regularly
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Primidone 125 mg PO 24 hourly at bedtime
May increase dose by 125 mg every 3 days up to 500 mg/day divided 12 hourly
May further increase dose by 250 mg/day every 3 days if needed
Maintenance dose: 750-1,500 mg/day PO divided 12 hourly
Max dose: 1,500 mg/day		 Adverse Reactions
  • Similar to Phenobarbital but more frequent
  • Patients usually develop tolerance to CNS effects (ataxia, drowsiness, dizziness, visual disturbances)
Special Instructions
  • Same as Phenobarbital
  • Adjust dose based on individual response to control seizures
  • Monitoring Primidone plasma concentration may aid in assessing control
    • Suggested therapeutic serum concentration: 23-55 micromol/L (5-12 mcg/mL)
  • Monitor CBC every 6 months
Carboxamides
Carbamazepine1 Initial dose: 100-200 mg PO 12-24 hourly
May increase dose by 100-200 mg weekly
Maintenance dose: 800-1,200 mg/day divided 6-12 hourly
Max dose: 1,600 mg/day		 Adverse Reactions
  • CNS effects (dizziness, drowsiness, headache, fatigue, nervousness, amnesia, insomnia, suicidal ideation); GI effects (nausea/vomiting, abdominal pain, diarrhea, dry mouth, anorexia); CV effects (hypotension, leg edema); Dermatologic effects (Stevens-Johnson syndrome, toxic epidermal necrolysis, rash which may be severe, photosensitivity reactions have been reported); Other effects (abnormal vision, nystagmus, ataxia, vertigo, abnormal gait, tremor, upper respiratory tract infection [URTI], hyponatremia, transient leukopenia)
  • May decrease side effects of Carbamazepine by starting at low dose and increasing slowly
  • Hypersensitivity reactions occur less frequently with Oxcarbazepine than Carbamazepine
  • Potentially fatal blood cell abnormalities have been reported following treatment
Special Instructions
  • Contraindicated in patients with AV block, history of bone marrow depression and acute porphyria with or within 14 days of MAO inhibitors
  • Use with caution in patients with cardiac, hepatic, renal disease, history of blood disorders, glaucoma, porphyria
  • Relationship between dose, serum concentration and response are variable; titrate dose according to response and side effects
  • Routine Carbamazepine serum level monitoring is not indicated except to assess compliance or possible toxic symptoms
    • Therapeutic serum concentration: 17-51 micromol/L (4-12 mcg/mL)
  • LFT, urinalysis, BUN, CBC, serum sodium should be done prior to and periodically during treatment
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Monitor for signs of blood, liver or skin toxicity; patient should inform physician immediately if signs and symptoms of blood toxicity occur (eg lethargy, fever, sore throat, mouth ulcers, skin rash, bruising or bleeding)
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
  • Carbamazepine and Oxcarbazepine:
    • HLA-B*1502 genetic testing is recommended to be done before starting therapy especially in patients of Asian descent; if positive, weigh if the benefit clearly outweighs risk of having Stevens-Johnson syndrome and toxic epidermal necrolysis
Eslicarbazepine Monotherapy or adjunctive therapy of partial-onset seizures:
Initial dose: 400 mg PO 24 hourly
May start at 800 mg PO 24 hourly if seizure reduction outweighs risk of adverse events during initiation
Increase dose by 400-600 mg weekly based on clinical response and tolerability
Maintenance dose: 800-1,600 mg PO 24 hourly
Oxcarbazepine1 Initial dose: 300 mg PO 12 hourly or 8-10 mg/kg PO divided 12 hourly
May increase dose by 600 mg/day weekly based on clinical response
Maintenance dose: 600-2,400 mg/day PO divided 12 hourly
Rufinamide Adjunctive therapy for seizures associated with Lennox-Gastaut syndrome in patients ≥17 years old:
Initial dose: 400-800 mg PO 12 hourly
May increase dose by 400-800 mg/day every other day
Max dose: 3,200 mg/day
Fatty Acid Derivatives
Tiagabine Adjunctive therapy with enzyme-inducing anticonvulsants2:
Initial dose: 4 mg PO 24 hourly x 1 week
May increase dose by 4-8 mg/day at weekly intervals
Maintenance dose: 32-56 mg/day PO divided 6-12 hourly
Adjunctive therapy with non-enzyme inducing anticonvulsants:
Patients require lower dosage and slower dosage titration schedule than patients taking enzyme-inducing anticonvulsants
12 mg/day is equivalent to 32 mg/day in patients receiving enzyme-inducing anticonvulsant		 Adverse Reactions
  • CNS effects (dizziness, nervousness, tiredness, somnolence, irritability, confusion, depression, difficulty in concentration, emotional lability); GI effects (diarrhea, abdominal pain, nausea); CV effects (chest pain, edema, hypertension, palpitation, tachycardia, syncope); Other effects (tremor, ataxia, nystagmus, bruising, rashes, speech difficulties, flu-like syndrome)
Special Instructions
  • Take with food to avoid rapid rise in plasma concentration
  • Avoid in patients with severe hepatic dysfunction
  • Use with caution in patients with hepatic impairment, adjust dose accordingly
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Withdraw drug or transition to another antiepileptic/anticonvulsant drug gradually (recommended over 2-3 weeks) to prevent increase in seizure frequency
Valproic acid (Sodium valproate, Valproate, Valproate semisodium, Divalproex Na) Initial dose: 10-15 mg/kg/day PO divided 6-12 hourly
May increase dose by 5-10 mg/kg/day weekly based on clinical response
Maintenance dose: 20-30 mg/kg/day
Max dose: 60 mg/kg/day
or
Initial dose: 600 mg/day PO divided 12 hourly
May increase dose by 200 mg/day every 3 days based on clinical response
Maintenance dose: 1-2 g/day
Max dose: 2.5 g/day
For patients unable to take oral doses:
Valproic acid may be given IV to start therapy or to continue therapy previously given orally
Initial dose: 10 mg/kg IV over 3-5 minutes
Followed by IV infusion as needed
Max dose: 2.5 g/day		 Adverse Reactions
  • CNS effects (headache, somnolence, behavioral changes, asthenia, dizziness, amnesia, depression); GI effects (abdominal cramps, nausea/vomiting, indigestion, anorexia, increased appetite, weight gain); Other effects (tremor, ataxia, hair loss, edema, increased bleeding time, thrombocytopenia, leukopenia, bone marrow depression, hepatic dysfunction)
Special Instructions
  • GI disturbances especially at the start of therapy may be decreased by taking medication with food or large amount of water, starting with a low dosage and increasing dose gradually, and using enteric-coated forms
  • Contraindicated in patients with significant hepatic impairment and urea cycle disorders
    • Increased risk of hyperammonemic encephalopathy in patients with urea cycle disorders
  • Avoid in females of childbearing age
    • Use lowest effective dose when the potential benefit of administration outweighs the potential risk
  • Use with caution in patients with congenital metabolic disorders, organic brain disease, severe seizure disorder, HIV and renal dysfunction
  • Routine Valproic acid serum level monitoring is not indicated except to assess compliance or assess possible toxic symptoms
    • Therapeutic serum concentration: 350-690 micromol/L (50-100 mcg/mL) at baseline and during the first 6 months of therapy, increased liver enzymes may respond to lower dose
  • Monitor CBC, PT/PTT especially prior to surgery, serum ammonia
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Watch out for signs of pancreatitis, blood and liver toxicity
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Gamma-aminobutyric acid (GABA)-Analogues
Gabapentin Monotherapy or adjunctive therapy:
Day 1: 300 mg PO 24 hourly
Day 2: 300 mg PO 12 hourly
Day 3: 300 mg PO 8 hourly
May increase dose by 300 mg/day every 2-3 days if required until effective epileptic control is achieved
Usual dose: 900-3,600 mg/day PO divided 8 hourly
Max dose: 3,600 mg/day		 Adverse Reactions
  • CNS effects (somnolence, dizziness, fatigue, anxiety, amnesia, headache, ataxia, tremor); GI effects (weight gain, dyspepsia, nausea/vomiting); Other effects (nystagmus, diplopia, pharyngitis, arthralgia, purpura, weakness)
  • Rarely pancreatitis, altered LFT, erythema multiforme, Stevens-Johnson syndrome, rhinitis, nervousness, myalgia and blood glucose fluctuations in DM
Special Instructions
  • Gabapentin: Use with caution in patients with severe renal impairment, history of psychotic illness
  • Pregabalin: Use with caution in patients with CHF, hypertension, DM, renal impairment
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Withdraw drug or transition to another anticonvulsant drug gradually (recommended ≥7 days) to prevent increase in seizure frequency
Pregabalin Initial dose: 150 mg/day PO divided 8-12 hourly
May increase dose by 300 mg/day PO after 3-7 days
Max dose: 600 mg/day after additional 7 days
Vigabatrin Adjunctive therapy for refractory focal-onset seizures:
Initial dose: 500 mg PO 12 hourly
May increase dose by 500 mg/day weekly based on clinical response and patient tolerance
Usual dose: 1,500 mg PO 12 hourly
Max dose: 3,000 mg/day		 Adverse Reactions
  • CNS effects (drowsiness, fatigue, dizziness, headache, paresthesia, impaired concentration, confusion, memory disturbances, ataxia, tremor); GI effects (weight gain, GI disturbances); Other effects (alopecia, rashes, urticaria, decrease in hemoglobin and liver enzymes, irreversible visual field defects ranging from mild-moderate and usually occurring after months or years of therapy)
  • May exacerbate myoclonic and absence seizures
Special Instructions
  • Avoid in patients with visual field defects
  • Use with caution in patient with history of psychosis or behavioral problems, renal impairment and in the elderly
  • Assess visual field functions before and during treatment regularly every 6 months
  • Withdraw drug or transition to another anticonvulsant drug gradually (recommended over 2-4 weeks) to prevent increase in seizure frequency
Hydantoins
Fosphenytoin Dose is expressed as Phenytoin equivalent (PE)
Status epilepticus:
Loading dose: 15-20 PE mg/kg IV given at a rate of 100-150 PE mg/min
Followed by maintenance dose of parenteral Fosphenytoin or oral/parenteral Phenytoin
Maintenance dose: 4-6 PE mg/kg/day IV/IM in divided doses
Non-emergent treatment of tonic-clonic or focal-onset seizures:
Loading dose: 10-20 PE mg/kg IV/IM
Maintenance dose: 4-6 PE mg/kg/day IV/IM in divided doses		 Adverse Reactions
  • Side effects may decrease with dose reduction or continued administration
  • GI effects (nausea/vomiting, abdominal pain, lack of appetite, gum tenderness, gingival hyperplasia); CNS effects (headache, dizziness, insomnia); Other effects (hirsutism, coarsening of facial features, mild hypersensitivity with skin rash)
  • Rarely, Stevens-Johnson syndrome, SLE or erythema multiforme, blood disorders (eg thrombocytopenia, leukopenia)
  • Prolonged administration may result in subtle changes in mental function and cognition
  • Rickets and osteomalacia have occurred and may be caused by interference of vitamin D and folate metabolism
  • Phenytoin toxicity may result in nystagmus, diplopia, slurred speech, ataxia, confusion and hyperglycemia
  • Severe CV reactions that are sometimes fatal have occurred with IV infusion of Fosphenytoin
  • Fosphenytoin: Burning, itching and paresthesia especially in groin area may occur; reducing the rate of infusion or temporarily stopping administration may relieve discomfort
Special Instructions
  • IV administration should be given slowly
    • Hypotension may occur with rapid administration
  • Adjust dose based on individual response to control seizures
  • Avoid IV administration in patients with sinus bradycardia, heart block and Stokes-Adams syndrome
  • Clinical authorities recommend that patients taking Phenytoin should be supplemented with Folate
  • Use with caution in patients with liver dysfunction, DM, CV disease, hypoalbuminemia and porphyria; IV should be used with caution in patients with heart failure, hypotension or MI
  • Routine Phenytoin serum level monitoring is not indicated except during dose adjustment and to assess compliance or possible toxicity
    • Therapeutic serum concentration: 40-80 micromol/L (10-20 mcg/mL)
  • Monitor ECG, BP and respiratory function during IV administration
    • Observe patient for 10-20 minutes after IV administration
  • Monitor for signs of blood or skin toxicity; patient should inform physician immediately if signs of blood toxicity occur (eg fever, sore throat, bruising, skin rash etc)
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Phenytoin (Phenytoin Na) Management of acute seizures:
Initial dose: 100-300 mg PO as single dose or in divided doses or 3-4 mg/kg PO as single dose or in divided doses
May increase dose by 100 mg every 2-4 weeks until desired response is obtained
Maintenance dose: 300-400 mg/day PO divided 6-8 hourly
Max dose: 600 mg/day
Status epilepticus:
Loading dose: 10-20mg/kg slow IV at a rate of ≤50 mg/min
May administer additional 5-10 mg/kg IV as single dose after 10 minutes if needed
Maintenance dose: 100 mg PO/IV 6-8 hourly
Succinimides
Ethosuximide Initial dose: 500 mg/day PO as single dose or divided 12 hourly
May increase dose by 250 mg/day every 4-7 days based on clinical response
Usual dose: 1-1.5 g/day PO divided 12 hourly
Max dose: 1.5 g/day		 Adverse Reactions
  • GI effects (nausea/vomiting, abdominal pain, anorexia, weight loss); CNS effects (headache, fatigue, lethargy, drowsiness, dizziness, ataxia, mild euphoria, depression); Other effect (hiccups)
  • Rarely, personality changes, dyskinesia, rashes, SLE, photophobia, Stevens-Johnson syndrome, erythema multiforme, abnormal renal function and LFT, hematologic effects (thrombocytopenia, leukopenia, aplastic anemia)
  • Mesuximide: Adverse reactions other than above are CNS effects (confusion, aggressiveness, hypochondrial behavior, emotional lability, insomnia, nervousness); Hematologic effects (eosinophilia, leukopenia, monocytosis, pancytopenia)
Special Instructions
  • Use with caution in patients with liver or renal dysfunction and porphyria
  • Monitoring Ethosuximide plasma concentration may aid in assessing control
    • Therapeutic serum concentration: 300-700 micromol/L (40-100 mcg/mL)
  • Monitor hepatic and renal function, CBC and urinalysis regularly
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Patient should inform physician immediately if signs of blood toxicity occur (eg fever, sore throat, bruising, skin rash, etc)
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Mesuximide
(Methsuximide, Methosuximide)		 Initial dose: 300 mg PO 24 hourly for the first week
May increase dose by 300 mg/day weekly
Max dose: 1-2 g/day PO in 3-4 divided doses
Other Anticonvulsants
Brivaracetam Initial dose: 50 or 100 mg/day PO/IV divided 12 hourly
May adjust dose between 50-200 mg/day PO/IV divided 12 hourly if needed
Max dose: 200 mg/day PO/IV
Max dose in patients with hepatic impairment: 150 mg/day PO/IV		 Adverse Reactions
  • CNS effects (somnolence, dizziness, convulsion, depression, anxiety, irritability, insomnia, vertigo); Respiratory effects (URTI, flu, cough); GI effects (nausea/vomiting, constipation); Other effects (decreased appetite, fatigue)
Special Instructions
  • Contraindicated in patients with end-stage renal disease or undergoing dialysis
  • Use with caution in patients with hepatic impairment, adjust dose accordingly
  • Monitor for suicidal ideation and behaviors
Cenobamate Week 1 and 2: 12.5 mg PO 24 hourly
Week 3 and 4: 25 mg PO 24 hourly
Week 5 and 6: 50 mg PO 24 hourly
Week 7 and 8: 100 mg PO 24 hourly
Week 9 and 10: 150 mg PO 24 hourly
Week 11 and onwards: 200 mg PO 24 hourly
May further increase dose by 50 mg/day PO every 2 weeks based on response
Max dose: 400 mg/day		 Adverse Reactions
  • CNS effects (cognitive dysfunction, drowsiness, fatigue, dizziness, visual changes, coordination abnormalities, aggressive behavior, psychosis, suicidal ideation); Other effects (QT prolongation, delayed hypersensitivity reaction)
Special Instructions
  • Avoid in patients with familial short QT syndrome
  • Use with caution in patients on drugs known to shorten QT interval
  • Use with caution in patients with renal and hepatic impairment
  • When discontinuing, gradually reduce the dose over ≥2 weeks
Felbamate Monotherapy for refractory focal-onset seizures:
Initial dose: 1,200 mg/day PO divided 6-8 hourly
May increase dose by 600 mg every 2 weeks based on clinical response up to 2,400 mg/day divided 6-8 hourly
Max dose: 3,600 mg/day
Adjunctive therapy for refractory focal-onset seizures:
Reduce dose of concomitant anticonvulsants by 20-33%
Initial dose: 1,200 mg/day PO divided 6-8 hourly
May increase dose by 1,200 mg/day weekly based on clinical response
Max dose: 3,600 mg/day		 Adverse Reactions
  • CNS effects (somnolence, headache, dizziness, insomnia, fatigue, nervousness); GI effects (anorexia, nausea/vomiting, weight loss, constipation, dyspepsia); Other effects (diplopia, photosensitivity, rashes, URTI, abnormal gait, tremor)
Special Instructions
  • Use only in severe epilepsy refractory to other treatments when advantages outweigh the risks
  • Patient should use protective measures to avoid UV radiation
  • Contraindicated in patients with hepatic impairment or history of blood disorders
  • Use with caution in patients with renal impairment
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Monitor CBC and LFT before and regularly during therapy
    • Continue to monitor CBC after discontinuation
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Fenfluramine Management of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome:
Initial dose: 0.1 mg/kg PO 12 hourly
May increase dose by 0.2 mg/kg PO 12 hourly after 1 week then by 0.35 mg/kg PO 12 hourly after another week based on tolerability
Max dose: 26 mg/day		 Adverse Reactions
  • Dravet Syndrome: GI effects (diarrhea, vomiting, constipation, drooling, salivary hypersecretion); CNS effects (somnolence, sedation, lethargy, ataxia, balance disorder, gait disturbance, status epilepticus); CV effect (increased BP); Other effects (decreased appetite, fatigue, pyrexia, upper respiratory tract infection, decreased weight, fall)
  • Lennox-Gastaut syndrome: GI effects (diarrhea, vomiting); CNS effect (somnolence); CV effect (abnormal echocardiogram); Other effects (decreased appetite, fatigue, malaise, asthenia)
Special Instructions
  • Use with caution in patients taking serotonergic drugs
  • Monitor BP and for presence of somnolence, sedation, suicidal behavior and thoughts, visual acuity changes and ocular pain during treatment
Lacosamide IV dose should only be used temporarily when oral dose is not feasible
Monotherapy for focal-onset and tonic-clonic seizures:
Initial dose: 50-100 mg PO/IV 12 hourly or 200 mg PO/IV as single dose followed by 100 mg PO/IV 12 hourly after 12 hours
May increase dose by 50 mg PO 12 hourly weekly
Maintenance dose: 300-400 mg/day
Max dose: 600 mg/day
Adjunctive therapy for focal-onset and tonic-clonic seizures:
Initial dose: 50 mg PO/IV 12 hourly
May increase dose by 50 mg PO 12 hourly weekly
Maintenance dose: 200-400 mg/day
Max dose: 400 mg/day		 Adverse Reactions
  • CNS effects (dizziness, headache, fatigue, ataxia, somnolence, impaired coordination, vertigo); Ophthalmologic effects (diplopia, blurring of vision, nystagmus); GI effects (nausea/vomiting, diarrhea); Local effects (contusion, pain/discomfort at injection site, irritation); Other effects (pruritus, syncope for dose >400 mg/day)
Special Instructions
  • Switching from IV to oral formulations makes use of the same total daily dose and frequency
  • IV Lacosamide is only used as a short-term alternative to oral therapy (eg in patients with GI disorders, difficulty swallowing, undergoing surgical procedures)
  • Use with caution in patients with conduction problems as Lacosamide may prolong PR interval
  • Use with caution in patients performing tasks which require alertness (eg driving, operating machineries) as ataxia and dizziness may occur during therapy
  • Lacosamide should be withdrawn gradually (by discontinuing over ≥1 week and/or tapering daily dosage by 200 mg/wk) to lessen risk for increased seizure frequency
Lamotrigine Monotherapy:
Initial dose: 25 mg PO 24 hourly x 2 weeks followed by 50 mg PO 24 hourly x 2 weeks
May increase dose by 50-100 mg every 1-2 weeks based on clinical response
Maintenance dose: 100-200 mg/day PO 24 hourly or divided 12 hourly
Max dose: 500 mg/day
Adjunctive therapy with enzyme-inducing anticonvulsants2:
Initial dose: 50 mg PO 24 hourly x 2 weeks followed by 50 mg PO 12 hourly x 2 weeks
May increase dose by 100 mg every 1-2 weeks based on clinical response
Maintenance dose: 200-400 mg/day PO divided 12 hourly
Max dose: 700 mg/day
Adjunctive therapy with Valproic acid:
Initial dose: 25 mg PO every other day x 2 weeks followed by 25 mg PO 24 hourly x 2 weeks
May increase dose by 25-50 mg every 1-2 weeks based on clinical response
Maintenance dose: 100-200 mg/day PO 24 hourly or divided 12 hourly		 Adverse Reactions
  • CV effects (chest pain, edema); CNS effects (dizziness, drowsiness, insomnia, headache, confusion, agitation); GI effects (nausea/vomiting); Other effects (photosensitivity, angioedema, blurred vision, tremor); Hypersensitivity effects (fever, malaise, flu-like symptoms, drowsiness, lymphadenopathy, facial edema, rarely hepatic dysfunction)
  • Skin rashes, including Stevens-Johnson syndrome and toxic epidermal necrolysis
    • Usually occur within 8 weeks of starting therapy
  • Symptoms associated with aseptic meningitis typically occur 1-42 days after starting of therapy and resolve upon discontinuation
Special Instructions
  • Use with caution in patients with impaired cardiac function, hepatic or renal impairment
  • Patient should inform doctor immediately if signs of rash, flu-like hypersensitivity symptoms, or signs and symptoms associated with aseptic meningitis develop
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Withdraw drug or transition to another anticonvulsant drug gradually by decreasing the dose to ~50%/week, over at least 2 weeks to prevent increase in seizure frequency
Levetiracetam Initial dose: 250-500 mg PO 12 hourly
May increase dose by 250-500 mg PO 12 hourly every 2-4 weeks
Max dose: 3 g/day		 Adverse Reactions
  • CNS effects (somnolence, dizziness, ataxia, headache, amnesia, depression, emotional lability, insomnia, aggression, nervousness, vertigo); GI effects (nausea/vomiting, anorexia); Other effects (weakness, tremor, diplopia)
Special Instructions
  • Use with caution in patients with renal impairment and/or severe hepatic impairment, adjust dose accordingly
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Perampanel Initial dose: 2 mg PO 24 hourly
May increase dose by 2 mg/day every 1-2 weeks
Maintenance dose: 4-8 mg/day
May further increase dose by 2 mg/day
Max dose: 12 mg/day		 Adverse Reactions
  • CNS effects (dizziness, somnolence; aggression, anger, anxiety, confusional state, ataxia, dysarthria, balance disorder, irritability, diplopia, blurred vision, vertigo, gait disturbance); Other effects (decreased/increased appetite, fatigue, weight gain, fall, nausea, back pain)
Special Instructions
  • Contraindicated in patients with moderate to severe renal impairment and/or severe hepatic impairment
  • Use with caution in patients with rare hereditary problems of galactose intolerance, Lapp-lactase deficiency or glucose-galactose malabsorption
  • Monitor for signs of suicidal ideation and behaviors
  • Avoid abrupt discontinuation of treatment
Topiramate Monotherapy:
Initial dose: 25 mg PO 24 hourly at night x 1 week
May increase dose by 25-50 mg/day divided 12 hourly every 1-2 weeks
Usual dose: 100 mg/day
Max dose: 500 mg/day
Adjunctive therapy:
Initial dose: 25-50 mg/day PO 24 hourly at night x 1 week
May increase dose by 25-100 mg/day PO in divided 12 hourly every 1-2 weeks
Usual dose: 200-400 mg/day PO divided 12 hourly		 Adverse Reaction
  • CNS effects (fatigue, confusion, paresthesia, somnolence, difficulty with concentration, mood changes); GI effects (weight loss, nausea, anorexia, diarrhea, taste perversion); Other effects (ataxia, abnormal vision, hyperthermia, risk of stone formation, metabolic acidosis)
  • Rare cases of acute myopia with or without secondary angle-closure glaucoma have been reported
Special Instructions
  • Maintain adequate hydration to reduce the risk of renal calculi
  • Use with caution in patients with hepatic or renal impairment
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • Discontinue use in patients with acute onset of decreased visual acuity or ocular pain
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency
Zonisamide Monotherapy:
Week 1 and 2: 100 mg PO 24 hourly
Week 3 and 4: 200 mg PO 24 hourly
Week 5 and 6: 300 mg PO 24 hourly
Maintenance dose: 300 mg PO 24 hourly
May further increase dose by 100 mg/day every 2 weeks
Max dose: 500 mg/day
Adjunctive therapy:
Initial dose: 100-200 mg/day PO divided 8-24 hourly
May gradually increase dose by 200-400 mg/day divided 8-24 hourly every 1-2 weeks
Max dose: 600 mg/day		 Adverse Reactions
  • CNS effects (somnolence, dizziness, headache, confusion, irritability, depression, psychosis, reduced concentration); GI effects (anorexia, nausea/vomiting, abdominal pain, weight loss); Other effects (nystagmus, paresthesia, renal calculi, psychomotor slowing, language or speech difficulties, pancreatitis, rhabdomyolysis, metabolic acidosis)
  • Isolated cases of aplastic anemia and agranulocytosis; Rarely severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis)
Special Instructions
  • Maintain adequate hydration to reduce the risk of renal calculi
  • Contraindicated in patients with hypersensitivity to sulfonamide and women who are lactating
  • Use with caution in patients with hepatic or renal impairment
  • Monitor BUN, serum creatinine, serum bicarbonate
  • Monitor for any emergence or worsening of depression, suicidal tendency, unusual changes in mood or behavior
  • If patient has unexplained rashes, withdraw drug
  • Withdraw drug or transition to another antiepileptic/anticonvulsant drug gradually to prevent increase in seizure frequency
1Extended-release preparations are available. Please see the latest MIMS for specific formulations and prescribing information.
2Enzyme-inducing antiepileptic drugs include Carbamazepine, Phenytoin, Primidone and Phenobarbital.

Benzodiazepines

Drug Dosage Remarks
Clobazam Adjunctive therapy for seizures associated with Lennox-Gastaut syndrome:
Day 1-6: 5-10 mg PO 12 hourly
Day 7-13: 10-20 mg PO 12 hourly
Day 14 onwards: 20-40 mg PO 12 hourly		 Adverse Reactions
  • Dose-dependent adverse CNS effects are common; Other adverse reactions have been reported but they are exceedingly rare
  • CNS effects (drowsiness, ataxia, fatigue, confusion, dizziness, vertigo, syncope, headache, slurred speech, depression, aggression, hostility); Respiratory effects (respiratory depression, apnea, cough); CV effect (hypotension); GI effects (nausea/vomiting, changes in appetite, weight gain/loss, changes in salivation); Other effects (injection site reaction, anaphylaxis, hypersensitivity reactions, muscle tremor, weakness, changes in libido, urinary retention, visual disturbances)
  • Benzodiazepines have been associated with anterograde amnesia
  • Thrombophlebitis and increase in liver enzymes with some IV formulations
  • Clonazepam: Most common adverse effect is drowsiness
  • Midazolam: Life-threatening respiratory and CV events have been reported
Special Instructions
  • Avoid use in patients with pre-existing CNS depression, acute and chronic respiratory insufficiency, sleep apnea, acute narrow-angle glaucoma and history of drug or alcohol dependence
  • Use with extreme caution, particularly in non-critical care settings, as these may cause severe respiratory depression, respiratory arrest or apnea
  • Use with caution in patients with chronic muscle weakness, renal or hepatic impairment, in patients receiving other CNS depressants and in the elderly
  • Withdraw drug or transition to another anticonvulsant drug gradually to prevent increase in seizure frequency or withdrawal symptoms
Clonazepam Initial dose:
1-2 mg PO 24 hourly at night x 4 days, gradually increased over 2-4 weeks
Maintenance dose: 4-8 mg/day PO divided 6-8 hourly
Once the maintenance dose has been reached, the daily amount may be given as a single dose at night
Max dose: 20 mg/day
Clorazepate (Clorazepate dipotassium, Dipotassium clorazepate) Adjunctive therapy:
Initial dose: 7.5 mg PO 8-12 hourly
Increase dose by ≤7.5 mg at weekly intervals
Max dose: 90 mg/day
Diazepam Adjunctive therapy:
2-10 mg PO 6-12 hourly
Status epilepticus:
5-10 mg IV
May be repeated in 10-15 minutes interval up to max dose
Max dose: 30 mg in 2-4 hours
Once seizure is controlled, administer up to 3 mg/kg via slow IV infusion over 24 hours to prevent recurrences
Rectal solution: 10 mg rectally
Max dose: 30 mg
Lorazepam Status epilepticus:
0.1 mg/kg IV/IM as single dose
May repeat in 10-15 minutes
Max dose: 4 mg/dose
Midazolam Status epilepticus:
0.2 mg/kg IM as single dose
Max dose: 10 mg/dose

Others

Drug Dosage Remarks
Anaesthetic
Propofol Status epilepticus:
Initial dose: 1-2 mg/kg IV bolus
Followed by 0.5-2 mg/kg every 3-5 minutes until seizures are suppressed
Max dose: 10 mg/kg
Continuous infusion: 20 mcg/kg/min continuous IV infusion
Titrate dose by 5-10 mcg/kg/min every 5 minutes until cessation of electrographic seizures or burst suppression is achieved
Usual dose: 30-200 mcg/kg/min
May administer additional 0.5-2 mg/kg every 3-5 minutes to continuous infusion titration rate for breakthrough status epilepticus		 Adverse Reactions
  • CV effects (decreased BP, bradycardia); CNS effects (convulsion, headache); GI effects (nausea/vomiting); Other effects (pain at injection site, fever, urine discoloration, anaphylactic-like reactions, apnea, involuntary muscle movements)
Special Instructions
  • Use with caution in patients with hypovolemia, epilepsy, lipid metabolism disorders, increased intracranial pressure and in the elderly
  • Avoid rapid bolus doses in high-risk patients
Diuretic
Acetazolamide Adjunctive therapy:
8-30 mg/kg/day PO in divided doses
Max dose: 375-1,000 mg/day		 Adverse Reactions
  • CNS effects (fatigue, depression, excitement, headache, confusion, drowsiness, dizziness); GI effects (weight loss, GI disturbances); GU effects (diuresis, crystalluria, polyuria, renal calculi, renal colic, nephrotoxicity); Metabolic effects (metabolic acidosis, hypokalemia, hyperuricemia); Other effects (malaise, ataxia, paresthesias, hepatic dysfunction, allergic skin reactions, fever, thirst, tinnitus); Rarely blood dyscrasia
  • Tolerance develops rapidly
Special Instructions
  • Contraindicated in Na and K depletion, hyperchloremic acidosis, chronic angle-closure glaucoma, marked hepatic and renal impairment, Addison’s disease, adrenocortical insufficiency, severe pulmonary obstruction, hypersensitivity to sulfonamides
  • Use with caution in patients likely to develop respiratory and severe metabolic acidosis, in patients with DM and in the elderly
  • Monitor plasma electrolytes and CBC regularly
  • Potassium supplements may be required
Hypnotic & Sedative
Paraldehyde 5-10 mL IM as single dose Adverse Reactions
  • CNS effects (CNS depression, dizziness, tremor); Local effects (injection site reaction, pain, sterile skin abscess, skin sloughing, fat necrosis, muscle irritation, nerve damage); Other effects (muscle cramps, rash, diaphoresis)
  • Nephrosis, toxic hepatitis, tolerance and physical dependence may occur with prolonged use
Special Instructions
  • Store properly as it decomposes on storage
    • Death from corrosive poisoning can occur if administered

Disclaimer

All dosage recommendations are for non-pregnant and non-breastfeeding women, and non-elderly adults with normal renal and hepatic function unless otherwise stated.  
Not all products are available or approved for above use in all countries.  
Products listed in the Drug Summary are based on indications stated in the locally approved product monographs.   
Please refer to local product monographs in Related MIMS Drugs for country-specific prescribing information.  

Related MIMS Drugs