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Home / Drugs / Starting with T / Topiramate

Topiramate (brand name Topamax) is an anticonvulsant drug produced by Ortho-McNeil Neurologics, a division of Johnson & Johnson. It is used to treat epilepsy in both children and adults. In children it is also indicated for treatment of Lennox-Gastaut syndrome (a disorder that causes seizures and developmental delays). It is also Food and Drug Administration (FDA) approved for, and now most frequently prescribed for, the prevention of migraines. [Wikipedia]
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ManufacturersOrtho mcneil janssen pharmaceuticals inc
Barr laboratories inc
Mylan pharmaceuticals inc
Sandoz inc
Teva pharmaceuticals usa inc
Watson laboratories inc
Zydus pharmaceuticals usa inc
Accord healthcare inc
Apotex inc etobicoke site
Aurobindo pharma ltd
Cipla ltd
Glenmark generics ltd
Invagen pharmaceuticals inc
Pliva hrvatska doo
Ranbaxy laboratories ltd
Roxane laboratories inc
Sun pharmaceutical industries ltd
Torrent pharmaceuticals ltd
Unichem laboratories ltd
Upsher smith laboratories inc
PackagersAmerisource Health Services Corp.
Apotex Inc.
A-S Medication Solutions LLC
Atlantic Biologicals Corporation
Aurobindo Pharma Ltd.
Avkare Incorporated
Barr Pharmaceuticals
Blenheim Pharmacal
Bryant Ranch Prepack
Cadila Healthcare Ltd.
Camber Pharmaceuticals Inc.
Cardinal Health
Cipla Ltd.
Cobalt Pharmaceuticals Inc.
Comprehensive Consultant Services Inc.
DAVA Pharmaceuticals
Dept Health Central Pharmacy
Dispensing Solutions
Diversified Healthcare Services Inc.
Glenmark Generics Ltd.
Greenstone LLC
Heartland Repack Services LLC
Innoviant Pharmacy Inc.
InvaGen Pharmaceuticals Inc.
Janssen-Ortho Inc.
Kaiser Foundation Hospital
Lake Erie Medical and Surgical Supply
Major Pharmaceuticals
McNeil Laboratories
Medisca Inc.
Nucare Pharmaceuticals Inc.
Ortho Mcneil Janssen Pharmaceutical Inc.
PD-Rx Pharmaceuticals Inc.
Pharmacy Service Center
Physicians Total Care Inc.
Pliva Inc.
Prepak Systems Inc.
Rebel Distributors Corp.
Remedy Repack
Resource Optimization and Innovation LLC
Shanghai Junjie Biotechnology Co. Ltd.
Southwood Pharmaceuticals
Stat Rx Usa
Sun Pharmaceutical Industries Ltd.
Teva Pharmaceutical Industries Ltd.
Torrent Pharmaceuticals
UDL Laboratories
Unichem Laboratories Ltd.
Upsher Smith Laboratories
Vangard Labs Inc.
Zydus Pharmaceuticals
SynonymsTipiramate [French]
Tipiramato [Spanish]
topiramate tablet
Topiramato [INN-Spanish]
Topiramatum [INN-Latin]
Topiramic acid


Used for the treatment and control of partial seizures and severe tonic-clonic (grand mal) seizures and also for the prevention of migraine headaches. In children it is also used for treatment of Lennox-Gastaut syndrome.


Topiramate is an anticonvulsant indicated in the treatment of epilepsy and migraine. Topiramate enhances GABA-activated chloride channels. In addition, topiramate inhibits excitatory neurotransmission, through actions on kainate and AMPA receptors. There is evidence that topiramate has a specific effect on GluR5 kainate receptors. It is also an inhibitor of carbonic anhydrase, particular subtypes II and IV, but this action is weak and unlikely to be related to its anticonvulsant actions, but may account for the bad taste and the development of renal stones seen during treatment. Its possible effect as a mood stabilizer seems to occur before anticonvulsant qualities at lower dosages. Topiramate inhibits maximal electroshock and pentylenetetrazol-induced seizures as well as partial and secundarily generalized tonic-clonic seizures in the kindling model, findings predective of a broad spectrum of antiseizure activities clinically.

mechanism of action

The precise mechanism of action of topiramate is not known. However, studies have shown that topiramate blocks the action potentials elicited repetitively by a sustained depolarization of the neurons in a time-dependent manner, suggesting a state-dependent sodium channel blocking action. Topiramate also augments the activity of the neurotransmitter gamma-aminobutyrate (GABA) at some subtypes of the GABAA receptor (controls an integral chloride channel), indicating a possible mechanism through potentiation of the activity of GABA. Topiramate also demonstrates antagonism of the AMPA/kainate subtype of the glutamate excitatory amino acid receptor. It also inhibits carbonic anhydrase (particularly isozymes II and IV), but this action is weak and unlikely to be related to its anticonvulsant actions.


Symptoms of overdose include abdominal pain, agitation, blurred vision, convulsions, depression, dizziness, double vision, drowsiness, impaired coordination, impaired mental activity, low blood pressure, reduced consciousness, severe diarrhea, sluggishness, and speech problems.


Not extensively metabolized, 70% of the dose is eliminated unchanged in the urine. The other 30% is metabolized hepatically to six metabolites (formed by hydroxylation, hydrolysis, and glucuronidation), none of which constitute more than 5% of an administered dose.


Rapid with pleak plasma concentrations occurring after 2 hours and a bioavailability of 80%.

half life

19 to 23 hours

route of elimination

Topiramate is not extensively metabolized and is primarily eliminated unchanged in the urine (approximately 70% of an administered dose).

drug interactions

Acetazolamide: Additive renal carbonic anhydrase inhibition may occur increasing the risk of crystaluria and renal calculi. Increased risk of nephrolithiasis. Consider altnerate therapy.

Brinzolamide: As both brinzolamide and topiramate are carbonic anhydrase inhibitors, there is an increased risk of adverse effects.The development of acid-base disorders with concurrent use of ophthalmic and oral carbonic anhydrase inhibitors has been reported. Avoid concurrent use of different carbonic anhydrase inhibitors when possible.

Carbamazepine: Carbamazepine may decrease the effectiveness of Topiramate by increase its clearance. Monitor for changes in the therapeutic and adverse effects of Topiramate if Carbamazepine is initiated, discontinued or dose changed. Adverse effects related to CNS depression have also been observed during concomitant therapy.

Chlorothiazide: Thiazide diuretics such as chlorothiazide may enhance the hypokalemic effect of topiramate. Thiazide diuretics may increase the serum concentration of topiramate. Monitor for increased topiramate concentrations/adverse effects (e.g., hypokalemia) with initiation/dose increase of a thiazide diuretic. Closely monitor serum potassium concentrations with concomitant therapy. Topiramate dose reductions may be necessary.

Ethinyl Estradiol: Topiramate may decrease the effect of the oral contraceptive, Ethinyl estradiol. An alternate form of contraception should be used during concomitant therapy.

Fosphenytoin: Increased phenytoin/decreased topiramate

Lithium: Topiramate could modify lithium levels

Maraviroc: Topiramate, a CYP3A4 inducer, may decrease the serum concentration of Maraviroc by increasing Maraviroc metabolism and clearance. A dose adjustment of Maraviroc may be required. Monitor for changes in Maraviroc therapeutic and adverse effects if Topiramate is initiated, discontinued or dose changed.

Mestranol: Topiramate may decrease the effect of the oral contraceptive, Mestranol. An alternate form of contraception should be used during concomitant therapy.

Phenytoin: Increased phenytoin/decreased topiramate

Tobramycin: Increased risk of nephrotoxicity

Triprolidine: The CNS depressants, Triprolidine and Topiramate, may increase adverse/toxic effects due to additivity. Monitor for increased CNS depressant effects during concomitant therapy.