METAPIR-50
Topiramate Tablets USP 50 mg
What it does
Topiramate is a medication that helps control seizures and prevent migraines.
Commonly used for: seizures (epilepsy), migraines
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
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Answers come only from this medicine's registration record, BNF monograph and interaction data - not medical advice.
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Sourcing - Kenya onlyRegistration & product details
Source: Zambia Medicines Regulatory Authority · fetched 2026-09-17 03:35:33 · updated 2026-09-24 03:35:34
Drug Interactions
66Severe (7)
Antiepileptics - decreases absorption
Iron chelators (dexrazoxane) might decrease the absorption of antiepileptics (fosphenytoin, phenytoin). Avoid.
Antiepileptics - decreases exposure
Lumacaftor is predicted to decrease the exposure to antiepileptics (carbamazepine, fosphenytoin, phenobarbital, phenytoin, primidone). Avoid.
Antiepileptics - decreases concentration
St John’s wort is predicted to decrease the concentration of antiepileptics (fosphenytoin, phenobarbital, phenytoin, primidone). Avoid.
Antiepileptics - increases risk of overheating and dehydration
Hydroxyzine potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Antiepileptics - increases risk of overheating and dehydration
Haloperidol potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Antiepileptics - decreases absorption
Dexrazoxane might decrease the absorption of antiepileptics (fosphenytoin, phenytoin). Avoid.
Antiepileptics - increases risk of overheating and dehydration
Oxybutynin potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Moderate (25)
Antiepileptics - increases concentration
Intravenous chloramphenicol increases the concentration of antiepileptics (fosphenytoin, phenytoin) and antiepileptics (fosphenytoin, phenytoin) affect the concentration of intravenous chloramphenicol
Antiepileptics - decreases concentration
Diazoxide decreases the concentration of antiepileptics (fosphenytoin, phenytoin) and antiepileptics (fosphenytoin, phenytoin) are predicted to decrease the effects of diazoxide. Monitor concentration
Antiepileptics - increases concentration
Disulfiramincreasestheconcentrationofantiepileptics (fosphenytoin,phenytoin).Monitorconcentrationandadjust dose.rStudy →AlsoseeTABLE12p.1520
Antiepileptics - increases concentration
Fluorouracilincreasestheconcentrationofantiepileptics (fosphenytoin,phenytoin).Monitorconcentrationandadjust dose.rAnecdotal 1xidneppA|snoitcaretnI A1 https://www.facebook.c (Books-Courses-Medic
Antiepileptics - decreases concentration
Folates are predicted to decrease the concentration of antiepileptics (fosphenytoin, phenobarbital, phenytoin, primidone). Monitor concentration and adjust dose.
Unknown (34)
Antiepileptics - increases risk of overheating and dehydration
Acetazolamide potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Antiepileptics - increases risk of visual disturbances
Alcohol potentially increases the risk of visual disturbances when given with antiepileptics (retigabine).
Antiepileptics - decreases exposure
Enzalutamide is predicted to slightly decrease the exposure to antiepileptics (brivaracetam).
Antiepileptics - decreases exposure
Apalutamidepotentiallydecreasestheexposureto antiepileptics(valproate).nTheoretical
Antiepileptics - increases concentration
Capecitabine increases the concentration of antiepileptics (fosphenytoin, phenytoin).
Data from BNF 85 (British National Formulary). This is not a substitute for professional medical advice. Matched via: class
About this medicine
Topiramate is a medication that helps control seizures and prevent migraines.
What it treats
- seizures (epilepsy)
- migraines
How it works
Topiramate works by stabilizing electrical activity in the brain, helping to prevent seizures and headaches.
Who it's for
This medication is for people with epilepsy or those who suffer from frequent migraines.
Drug class
Antiepileptics
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: Topiramate
BNF-referencedTopiramate is an antiepileptic medication primarily used for the treatment of epilepsy and migraine prevention. It is effective as monotherapy for generalized tonic-clonic seizures and as adjunctive therapy for focal seizures. It works by modulating neurotransmitter activity and blocking neuronal excitability, thus preventing the occurrence of seizures and alleviating migraine symptoms.
Indications
- Monotherapy for generalized tonic-clonic seizures
- Adjunctive treatment for focal seizures with or without secondary generalization
- Migraine prevention
Dosage
Children: For children aged 6–17 years, initially 0.5–1 mg/kg once daily (max. per dose 25 mg) for 1 week, then increased in steps of 250–500 micrograms/kg twice daily, maximum 500 mg per day. Doses to be taken in 2 divided doses.
Adults: Initially, 5–10 mg daily in 1–2 divided doses, then increased in steps of 5–10 mg/24 hours every week; maintenance 100–200 mg daily in 2 divided doses, adjusted according to response, with a maximum of 500 mg daily.
Mechanism of action
Topiramate exerts its pharmacological effects through several mechanisms, including the inhibition of voltage-dependent sodium channels, stimulation of GABA-A receptor activity, and reduction of glutamate activity at AMPA and kainate receptors. This combination increases inhibitory neurotransmission and decreases excitatory activity in the brain, thereby preventing seizures and migraines.
Pharmacodynamics
Topiramate reduces neural pathway excitability, effectively preventing seizures and migraine symptoms. However, it is associated with potential adverse effects such as metabolic acidosis, mood changes, suicidal thoughts, and an increased risk of kidney stones, particularly when used with other medications like valproic acid, which can lead to hypothermia.
Pharmacokinetics
Topiramate is well-absorbed after oral administration, with peak plasma concentrations typically occurring within 2 hours. It has a half-life of approximately 21 hours and is primarily excreted unchanged in the urine. The pharmacokinetics may be affected by renal impairment, necessitating dose adjustments.
Contra-indications
- Acute porphyrias
- Severe hepatic impairment
Adverse effects
- Alopecia
- Anemia
- Anxiety
- Appetite abnormality
- Asthenia
- Behavioral abnormalities
- Cognitive impairment
- Concentration impairment
- Confusion
- Constipation
- Cough
- Depression
- Diarrhea
- Dizziness
- Drowsiness
- Dry mouth
- Dyspnea
- Ear discomfort
- Eye disorders
- Feeling abnormal
- Fever
- Gait abnormality
- Gastrointestinal discomfort
- Gastrointestinal disorders
- Hemorrhage
- Hypersensitivity
- Joint disorders
- Malaise
- Memory loss
- Mood alterations
- Movement disorders
- Muscle weakness
- Nasal complaints
Interactions
- Topiramate may decrease exposure to imatinib
Precautions
- Caution in patients with mild to moderate hepatic impairment
- May impair performance of skilled tasks, such as driving
- Monitor for risk of suicidal thoughts and behavior
Pregnancy
Avoid unless potential benefit outweighs risk; toxicity observed in animal studies.
Breast-feeding
Use with caution; limited data available.
Storage
Store at room temperature, away from moisture and heat.
Formulations
- Topiramate 25 mg capsules
- Topiramate 50 mg capsules
- Topiramate 100 mg capsules
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
Molecular reference: Topiramate
PubChem CID 5284627Molecular formula: C12H21NO8S
Mechanism of action
A seizure is an abnormal and unregulated electrical discharge occurring in the brain. This leads to transient interruption in brain function, manifested by reduced alertness, abnormal sensations, and focal involuntary movements or convulsions. Several types of seizures exist, with common types including tonic-clonic seizures and partial onset seizures. The exact mechanisms by which topiramate exerts pharmacological actions on seizures and migraines are currently not fully characterized. Several properties of this drug, however, are likely to contribute to its therapeutic effects. Topiramate has been observed to exert actions on voltage-dependent sodium channels, GABA receptors, and glutamate receptors. Topiramate stimulates GABA-A receptor activity at brain non-benzodiazepine receptor sites and reduces glutamate activity at both AMPA and kainate receptors. Normally, GABA-A receptors are inhibitory and glutaminergic receptors are stimulatory for neuronal activity. By increasing GABA activity and inhibiting glutamate activity, topiramate blocks neuronal excitability, preventing seizures and migraines. Additionally, it blocks the voltage-dependent sodium channels, further blocking seizure activity. Topiramate has been shown to inhibit various carbonic anhydrase isozymes, but the clinical significance of this is unknown at this time. The precise mechanism of action is unknown. Electrophysiological and biochemical studies on cultured neurons demonstrated that topiramate blocks the action potentials elicited repetitively by a sustained depolarization of the neurons in a time dependent manner; this effect suggests a state-dependent sodium channel blocking action. Also topiramate increases the frequency at which gamma-aminobutyric acid (GABA) activates GABA-A receptors, thereby enhancing GABA-induced influx of chloride ions into neurons. Thus, it appears that topiramate exerts it effects by potentiation of the activity of the inhibitory neurotransmitter, GABA. In addition, topiramate antagonizes the ability of kainate to activate the kainate/AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid; non-NMDA) subtype of excitatory amino acid (glutamate) receptor, but has no apparent effect on the activity of N-methyl-D-aspartate (NMDA) at the NMDA receptor subtype. These effects of topiramate are concentration-dependent within the range of 1 to 200 micromoles. Although the precise mechanism of action of topiramate is unknown, data from electrophysiologic and biochemical studies have revealed 4 properties that may contribute to the drug's efficacy for seizure disorders and migraine prophylaxis. At pharmacologically relevant concentrations, topiramate blocks voltage-dependent sodium channels; augments the activity of gamma-aminobutyric acid (GABA) at some subtypes of the GABA-A receptor; antagonizes the AMPA/kainate subtype of the glutamate receptor; and inhibits carbonic anhydrase (particularly CA-II and CA-IV isoenzymes). In general, anticonvulsant drugs are thought to act by one or more of the following mechanisms: modulating voltage-dependent ion (e.g., sodium) channels involved in action potential propagation or burst generation, enhancement of GABA inhibitory activity, and/or inhibition of excitatory amino acid neurotransmitter (e.g., glutamate, aspartate) activity. Topiramate exhibits effects on cultured neurons similar to those observed with phenytoin and carbamazepine, and such effects are suggestive of an inactive state-dependent block of voltage-dependent sodium channels. Topiramate reduces the duration of epileptiform bursts of neuronal firing and decreases the number of action potentials in studies of cultured rat hippocampal neurons with spontaneous epileptiform burst activity. Topiramate also decreases the frequency of action potentials elicited by depolarizing electric current in cultured rat hippocampal neurons. Depolarization and firing of an action potential results from the rapid inflow of sodium ions throug
Pharmacodynamics
Topiramate prevents the occurrence of seizures and prevents migraine symptoms by reducing neural pathway excitability. It is important to note that this drug may cause metabolic acidosis, mood changes, suicidal thoughts and attempts, as well as kidney stones. When topiramate is combined with [valproic acid], it is known to cause hypothermia.
Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.
This drug in other countries
The same active ingredient registered across other registries we cover - including different brands.
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- ADCO TOPIRAMATE TABLETS 200 mg
- ADCO TOPIRAMATE TABLETS 25 mg
- ADCO TOPIRAMATE TABLETS 50 mg
- COVAN-TOPRAX 100 mg
- COVAN-TOPRAX 200 mg
- EPIMATE 100 · Medox Pharmaceuticals
- EPIMATE 25 · Medox Pharmaceuticals
- EPIMATE 50 · Medox Pharmaceuticals
- METAPIR - 50 · Micro Labs
- METAPIR 100MG · Micro Labs
- TOPAMAX 25MG · Johnson & Johnson