Formulary
Topiramate: Indications, Dosing, Side Effects and Interactions
Topiramate clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 9 min read
Topiramate: Indications, Dosing, Side Effects and Interactions
Topiramate clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Monotherapy of generalised tonic-clonic seizures or focal seizures with or without secondary generalisation**
- **Child** (By Mouth): 6-17 years Initially 0.5-1 mg/kg once daily (max. per dose 25 mg) for 1 week, dose to be taken at night, then increased in steps of 250-500 micrograms/kg twice daily, dose to be increased by a maximum of 25 mg twice daily at intervals of 1-2 weeks; usual dose 50 mg twice daily (max. per dose 7.5 mg/kg twice daily), if child cannot tolerate titration regimens recommended above then smaller steps or longer interval between steps may be used; maximum 500 mg per day.
- **Adult** (By Mouth): Initially 25 mg once daily for 1 week, dose to be taken at night, then increased in steps of 25-50 mg every 1-2 weeks, dose to be taken in 2 divided doses; usual dose 100-200 mg daily in 2 divided doses, adjusted according to response, doses of 1 g daily have been used in refractory epilepsy; maximum 500 mg per day.
**Adjunctive treatment of generalised tonic-clonic seizures or focal seizures with or without secondary generalisation,Adjunctive treatment**
- **Child** (By Mouth): for seizures associated with Lennox-Gastaut syndrome 2-17 years Initially 1-3 mg/kg once daily (max. per dose 25 mg) for 1 week, dose to be taken at night, then increased in steps of 0.5-1.5 mg/kg twice daily, dose to be increased by a maximum of 25 mg twice daily at intervals of 1-2 weeks; usual dose 2.5-4.5 mg/kg twice daily (max. per dose 7.5 mg/kg twice daily), if child cannot tolerate recommended titration regimen then smaller steps or longer interval between steps may be used; maximum 400 mg per day.
- **Adult** (By Mouth): Initially 25-50 mg once daily for 1 week, dose to be taken at night, then increased in steps of 25-50 mg every 1-2 weeks, dose to be taken in 2 divided doses; usual dose 200-400 mg daily in 2 divided doses; maximum 400 mg per day.
**Migraine prophylaxis**
- **Adult** (By Mouth): Initially 25 mg once daily for 1 week, dose to be taken at night, then increased in steps of 25 mg every week; usual dose 50-100 mg daily in 2 divided doses; maximum 200 mg per day.
**Monotherapy of generalised tonic-clonic seizures or focal seizures with or without secondary generalisation for topiramate**
- **Child 6-17 years** (By mouth): Initially 0.5-1 mg/kg once daily (max. per dose 25 mg) for 1 week, dose to be taken at night, then increased in steps of 250-500 micrograms/kg twice daily, dose to be increased by a maximum of 25 mg twice daily at intervals of 1-2 weeks; usual dose 50 mg twice daily (max. per dose 7.5 mg/kg twice daily), if child cannot tolerate titration regimens recommended above then smaller steps or longer interval between steps may be used; maximum 500 mg per day.
**Adjunctive treatment of generalised tonic-clonic seizures or focal seizures with or without secondary generalisation, Adjunctive treatment for seizures associated with Lennox-Gastaut syndrome for topiramate**
- **Child 2-17 years** (By mouth): Initially 1-3 mg/kg once daily (max. per dose 25 mg) for 1 week, dose to be taken at night, then increased in steps of 0.5-1.5 mg/kg twice daily, dose to be increased by a maximum of 25 mg twice daily at intervals of 1-2 weeks; usual dose 2.5-4.5 mg/kg twice daily (max. per dose 7.5 mg/kg twice daily), if child cannot tolerate recommended titration regimen then smaller steps or longer interval between steps may be used; maximum 400 mg per day.
**Migraine prophylaxis for topiramate**
- **Child 16-17 years** (By mouth): Initially 25 mg once daily for 1 week, dose to be taken at night, then increased in steps of 25 mg every week; usual dose 50-100 mg daily in 2 divided doses, if child cannot tolerate recommended titration regimen then smaller steps or longer interval between steps may be used; maximum 200 mg per day.
Cautions
Avoid in Acute porphyrias ; risk of metabolic acidosis; risk of nephrolithiasis-ensure adequate hydration (especially in strenuous activity or warm environment)
Side effects
Common or very common Alopecia; anaemia; anxiety; appetite abnormal; asthenia; behaviour abnormal; cognitive impairment; concentration impaired; confusion; constipation; cough; depression; diarrhoea; dizziness; drowsiness; dry mouth; dyspnoea; ear discomfort; eye disorders; feeling abnormal; fever (in children); gait abnormal; gastrointestinal discomfort; gastrointestinal disorders; haemorrhage; hypersensitivity; joint disorders; malaise; memory loss; mood altered; movement disorders; muscle complaints; muscle weakness; nasal complaints; nasopharyngitis; nausea; oral disorders; pain; seizures; sensation abnormal; skin reactions; sleep disorders; speech impairment; taste altered; tinnitus; tremor; urinary disorders; urolithiases; vertigo (in children); vision disorders; vomiting (in children); weight changes Uncommon Abnormal sensation in eye; anhidrosis; arrhythmias; aura; cerebellar syndrome; consciousness impaired; crying; drooling; dry eye; dysgraphia; dysphonia; eosinophilia (in children); facial swelling; hallucinations; hearing impairment; hyperthermia (in children); hypokalaemia; hypotension; influenza like illness; learning disability (in children); leucopenia; lymphadenopathy; metabolic acidosis; musculoskeletal stiffness; palpitations; pancreatitis; paranasal sinus hypersecretion; peripheral coldness; peripheral neuropathy; polydipsia; psychotic disorder; renal pain; sexual dysfunction; smell altered; suicidal behaviours; syncope; thinking abnormal; thirst; thrombocytopenia; vasodilation Rare or very rare Eye inflammation; face oedema; glaucoma; hepatic disorders; limb discomfort; neutropenia; Raynaud's phenomenon; renal tubular acidosis; severe cutaneous adverse reactions (SCARs); unresponsive to stimuli Side-effects, further information Topiramate has been associated with acute myopia with secondary angle-closure glaucoma, typically occurring within 1 month of starting treatment. Choroidal effusions resulting in anterior displacement of the lens and iris have also been reported. If raised intra-ocular pressure occurs: seek specialist ophthalmological advice; use appropriate measures to reduce intra-ocular pressure and stop topiramate as rapidly as feasible.
Interactions
**Severe interactions:**
- Systemic hormonal contraceptives In a pharmacokinetic interaction study in healthy volunteers with a concomitantly administered combination oral contraceptive product containing 1 mg norethindrone...
- However, differences in AUC for the total active moiety between treatment with risperidone alone and combination treatment with topiramate were not statistically significant.
- There were no significant changes in the systemic exposure of the risperidone total active moiety or of topiramate.
- The steady-state pharmacokinetics of HCTZ were not significantly influenced by the concomitant administration of topiramate.
**Other interactions (46):**
- Effects of Topamax on other antiepileptic medicinal products The addition of Topamax to other AEDs (phenytoin, carbamazepine, valproic acid, phenobarbital, primidone) has no effect on their...
- Consequently, any patient on phenytoin showing clinical signs or symptoms of toxicity should have phenytoin levels monitored.
- A pharmacokinetic interaction study of patients with epilepsy indicated the addition of topiramate to lamotrigine had no effect on steady-state plasma concentration of lamotrigine at topiramate...
- In addition, there was no change in steady-state plasma concentration of topiramate during or after removal of lamotrigine treatment (mean dose of 327 mg/day).
- Topiramate inhibits the enzyme CYP2C19 and may interfere with other substances metabolized via this enzyme (e.g., diazepam, imipramin, moclobemide, proguanil, omeprazol).
- Effects of other antiepileptic medicinal products on Topamax Phenytoin and carbamazepine decrease the plasma concentration of topiramate.
Pregnancy
Important safety information For topiramate MHRA/CHM advice: Antiepileptics: risk of suicidal thoughts and behaviour (August 2008) See Epilepsy . MHRA/CHM advice: Antiepileptic drugs: updated advice on switching between different manufacturers' products (November 2017) See Epilepsy and see also Prescribing and dispensing information . MHRA/CHM advice: Antiepileptic drugs in pregnancy: updated advice following comprehensive safety review (January 2021) See Epilepsy . MHRA/CHM advice: Topiramate ( Topamax ): start of safety review triggered by a study reporting an increased risk of neurodevelopmental disabilities in children with prenatal exposure (July 2022) The MHRA has started a new safety review of topiramate following a large observational study that found a dose-dependent association between prenatal exposure and an increased risk of autism spectrum disorders, intellectual disability, and neurodevelopmental disorders in children. Healthcare professionals are reminded that topiramate must be prescribed according to current guidance. In addition, females of childbearing potential or their carers should be counselled on the importance of avoiding pregnancy due to these emerging risks, as well as the established risks associated with topiramate use in pregnancy. MHRA/CHM advice: Topiramate ( Topamax ): introduction of new safety measures, including a Pregnancy Prevention Programme (June 2024) Following the safety review above, the MHRA concluded that the use of topiramate during pregnancy is associated with significant harm to the unborn child, including a higher risk of congenital malformations and low birth-weight, and a potential increased risk of intellectual disability, autism spectrum disorders, and ADHD. Topiramate must not be used in females of childbearing potential unless the conditions of the Pregnancy Prevention Programme are met (see Conception and contraception ). Use of topiramate in pregnancy is contra-indicated for migraine prophylaxis, and it must only be considered for epilepsy if there is no suitable alternative treatment (see Pregnancy ). Female patients (and their carers) must be fully informed of the risks associated with the use of topiramate during pregnancy; supporting materials have been provided to use in the implementation of the Pregnancy Prevention Programme (see Prescribing and dispensing information ). The MHRA advises that: Prescribers must identify all new and existing females of childbearing potential on topiramate, explain clearly the conditions of the Pregnancy Prevention Programme, provide the Patient Guide, and complete and sign the Risk Awareness Form (at treatment initiation and at each annual review)-copies of the form must be given to the patient or carer and, if necessary, sent to their GP; Pharmacists must ensure topiramate is dispensed in whole packs whenever possible-all packs dispensed to females of childbearing potential should have a warning symbol either on the carton or via a sticker. They must also provide the Patient Card and check if the patient is using highly effective contraception, if they are not, patients should be advised to contact their GP for a follow-up appointment.
Breast feeding
Manufacturer advises avoid-present in milk.
Hepatic impairment
Manufacturer advises caution (risk of decreased clearance).
Renal impairment
Use with caution. M Dose adjustments Half usual starting and maintenance dose if creatinine clearance 70 mL/minute or less (reduced clearance and longer time to steady-state plasma concentration). M See Prescribing in renal impairment .
Medicinal forms
Solution,Tablet,Capsule,Suspension,Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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