Topiramate
Anti-epileptic · Sulphamate
Indications
Adjunctive therapy for partial seizures, with or without secondary generalized seizures, Lennox Gastaut syndrome and primary generalized tonic clonic seizures in patients inadequately controlled by other anticonvulsants. Migraine prophylaxis. Monotherapy of generalized tonic-clonic seizures or focal seizures with or without secondary generalization.
Dosage
Adults: Monotherapy of generalized tonic-clonic seizures or focal seizures with or without secondary generalization: Initially 25 mg once daily at night for 1 wk, increased in steps of 25-50 mg in 2 divided doses every 1-2 wks, usual dose 100-200 mg daily in 2 divided doses, adjusted according to response, 1 gm daily dose have been used in refractory epilepsy, max 500 mg daily. Adjunctive treatment: Initially 50 mg daily for one wk, then increase by 50 mg in two divided doses daily at wkly intervals Usual maintenance, 200-400 mg daily in two divided doses; max 400 mg daily. Use lower dose and longer interval between increments if patient is unable to tolerate titration regimen. Migraine prophylaxis: Initially 25 mg once daily at night for 1 wk, then increased in steps of 25 mg every wk, usual dose 50-100 mg daily in 2 divided doses. Max 200 mg daily. Children: Monotherapy of generalised…
Adverse Effects
Ataxia, difficulty concentrating, confusion, dizziness, fatigue, paraesthesia, somnolence, emotional lability, depression, CNS disturbances, headache, asthenia, sedation, wt change, GI upset, dry mouth, anorexia, insomnia, dysgeusia, speech and visual disturbances, nystagmus, cognitive disorders, convulsions, tremor, anxiety, hypoaesthesia, mood changes, agitation, abnormal behaviour, tinnitus, ear pain, dyspnoea, impaired balance and coordination, arthralgia, myalgia, muscle spasm, anaemia, nasal congestion, rhinorrhoea, epistaxis, cough, nephrolithiasis, pollakiuria, dysuria, alopecia, rash, pruritus, pyrexia. Rarely, acute myopia with secondary angle-closure glaucoma.
Risk Factor (Pregnancy/Lactation)
Pregnancy: Risk cannot be ruled out. Lactation: Contraindicated or not recommended. Precautions: Renal or hepatic impairment. Patients at risk of nephrolithiasis; maintain adequate hydration. History of eye disorders. Monitor patients for signs of depression and suicidal thoughts. Risk factors for metabolic acidosis; monitor serum bicarbonate and reduce dose or withdraw if occurs. Monitor for wt loss. Withdraw gradually.
Interactions
Phenytoin, carbamazepine, digoxin, oral contraceptives, agents causing nephrolithiasis, hydrochlorothiazide, pioglitazone, metformin, lithium, risperidone, valproate, CNS depressants, alcohol, St John's wort, imipramine, moclobemide, proguanil, omeprazole, glibenclamide.
Advice to Patient
Take with or without meals. Do not chew or crush tablets, swallow whole. Do not stop taking medication abruptly, gradually lower the dose and then stop. Contact prescriber if there is change in mental status, change in gait, change in vision, decrease in sweating, muscle cramps, weakness, tremors, irregular heartbeat, chest pain, palpitations, hearing loss, difficulty in breathing, skin rash, cough, periorbital pain, worsening of condition, loss of control on seizure occur. Avoid alcohol during therapy. Take sufficient amount of fluids (2-3 litres per day) to maintain hydration, unless restricted by the prescriber. Carry identification card mentioning you have epilepsy and names of all medications you take. On start of therapy or change of dosage, watch patient for suicidal tendency.
Pharmacokinetics
Note: Immediate release preparations are bioequivalent (sprinkle capsule and tablet); extended release capsules administered once daily is bioequivalent to twice daily administration of immediate release formulations. Absorption: Good, rapid; immediate release formulation is unaffected by food. Metabolism: Hepatic. Bioavailability: Approx. 80% (immediate release). Half-life elimination: Immediate release: Not receiving concomitant enzyme inducers or valproic acid: Neonates (full-term) with hypothermia: Approx. 43 hrs. Infants and Children 9 mths to <4 yrs: 10.4 hrs. Children 4-7 yrs: Mean range: 7.7-8 hrs. Children 8-11 yrs: Mean range: 11.3-11.7 hrs. Children and Adolescents 12-17 yrs: Mean range: 12.3-12.8 hrs. Receiving concomitant enzyme inducers (e.g., carbamazepine, phenytoin, phenobarbital): Neonates (full-term) with hypothermia: 26.5 hrs. Infants and Children 9 mths to <4 yrs:…
Unlicensed Use
Children: Migraine prophylaxis: 16-18 yr, initially 25 mg at night for 1 wk then increased in steps of 25 mg daily at wkly intervals; usual dose 50-100 mg daily in 2 divided doses, max 200 mg daily. If child cannot tolerate titration regimens recommended above then smaller steps or longer interval between steps may be used.
Brands with this active ingredient
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