Topiramate Carbamazepine

Valproic acid is a potent inhibitor of histone deacetylase and through this mechanism changes the transcription of many genes. A similar effect, but to a lesser degree, is shown by some other antiseizure drugs (topiramate, carbamazepine, and a metabolite of levetiracetam). 

CYP2C19 <5 5 Amitriptyline S-mephenytoin Omeprazole Phenytoin Phenobarbital Propranolol Diazepam Fluoxetine Fluvoxamine Ketoconazole Omeprazole Ticlopidine Topiramate Carbamazepine Rifampin... 

Phenobarbital, phenytoin, and valproic acid may increase the metabolism of carbamazepine by inducing CYP3A4 carbamazepine may enhance the biotransformation of phenytoin. Concurrent administration of carbamazepine may lower concentrations of valproic acid, lamotrigine, tiagabine, and topiramate. Carbamazepine reduces both the plasma concentration and therapeutic effect of haloperidol. The metabolism of carbamazepine may be inhibited by propoxyphene, erythromycin, cimetidine, fluoxetine, and isoniazid. 

Topiramate interacts with other antiepileptic agents, including carbamazepine, phenytoin, and vaiproate, resulting in more rapid metabolism and elimination and reduced plasma concentration of topiramate. Carbamazepine can reduce topiramate serum levels by up to 25%. Phenytoin can lower topiramate serum levels by up to 25%, while topiramate has been shown to increase phenytoin serum levels by about 50%. 

Anticonvulsants Carbamazepine, valproic acid, gabapentin, topiramate... 

Vigabatrin (not marketed in United States), tiagabine, topiramate, gabapentin, carbamazepine, lamotrigine... 

Epilepsy is a clinical disorder characterized by spontaneous, recurrent seizures arising from excessive electrical activity in certain parts of the brain [51]. Currently available drugs, such as phenytoin, carbamazepine, valproic acid, lamotrigine, and topiramate (for molecular structures see Fig. 6), provide symptomatic seizure suppression in only 60-70% of those receiving treatment [52-54]. These drugs are also associated with unwanted side... 

Pharmacotherapy is the cornerstone of acute and maintenance treatment of bipolar disorder. Mood-stabilizing drugs are the usual first-choice treatments and include lithium, divalproex, carbamazepine, and lamotrigine. Atypical antipsychotics other than clozapine are also approved for treatment of acute mania. Lithium, lamotrigine, olanzapine, and aripiprazole are approved for maintenance therapy. Drugs used with less research support and without Food and Drug Administration (FDA) approval include topiramate and oxcarbazepine. Benzodiazepines are used adjunctively for mania. 

Topiramate Topamax Suspension 300 mg/5 mL Tablet 25, 100, 200 mg Doses should be slowly adjusted up and down according to response and adverse effects (e.g., 150-300 mg twice daily and increase by 300-600 mg/day at weekly intervals) 50-200 mg/day in divided doses drug-drug interactions than carbamazepine, but causes more gastrointestinal side effects and hyponatremia Evidence is limited regarding efficacy Not recommended for the... 

Risperidone Aripiprazole 2D6 > 3A4 2D6, 3A4 Carbamazepine and phenytoin topiramate hypericum (St. John s Wort). Paroxetine, fluoxetine, sertraline (high dose) grapefruit juice 2D6 or 3A4 substrates acting as competitive inhibitors. 

Quetiapine 3A4 2D6, 2C9 Carbamazepine and phenytoin topiramate prednisolone. Fluvoxamine fluoxetine sertraline (high dose) CYP3A4 substrates grapefruit juice. 

Carbamazepine, phenytoin, valproate, gabapentin, lamotrigine, levetiracetam, tiagabine, topiramate, zonisamide... 

Commonly used drugs that induce liver enzymes (rifampin, phenytoin, carbamazepine, barbiturates, primidone, topiramate) and reduce efficacy of CHC... 

Anticonvulsants (barbiturates, including phenobar-bital and primidone carbamazepine felbamate phenytoin topiramate vigabatrin)... 

U.K. guidelines Carbamazepine Lamotrigine Oxcarbazepine Topiramate Valproic acid ... 

U.S. Expert Panel 2005 Valproic acid Carbamazepine Lamotrigine Oxcarbazepine Phenobarbital Phenytoin Topiramate Valproic acid Children Carbamazepine Phenobarbital Phenytoin Topiramate Valproic acid Lamotrigine... 

Valproic acid may cause less cognitive impairment than phenytoin and phenobarbital. Some of the newer agents (e.g., gabapentin and lamotri-gine) have been shown to cause fewer cognitive impairments than the older agents (e.g., carbamazepine). Topiramate may cause substantial cognitive impairment. 

Anticonvulsants. Several antiseizure medicines have been studied in the treatment of PTSD, and some results have been encouraging. Open label studies, first with carbamazepine (800-1200 mg/day) and later with valproate (500-2000 mg/ day), demonstrated overall improvement in PTSD patients, though not for intrusive recollections per se. Recent open label studies of gabapentin, lamotrigine, tiagabine, and topiramate have suggested these anticonvulsants might also be helpful for some PTSD symptoms. 

Drugs that can decrease carbamazepine serum levels include charcoal, cisplatin, doxorubicin, felbamate, hydantoins, rifampin, phenobarbital, primidone, theophylline. The serum levels of oral contraceptives, haloperidol, bupropion, anticoagulants, felbamate, valproic acid, felodipine, tricyclic antidepressants, acetaminophen, ziprasidone, voriconazole, topiramate, tiagabine, olanzapine, and lamotrigine can be lowered by carbamazepine. 

Concomitant therapy On occasion, the addition of topiramate to phenytoin may require an adjustment of the dose of phenytoin to achieve optimal clinical outcome. The addition or withdrawal of phenytoin and/or carbamazepine during adjunctive therapy with topiramate may require adjustment of the dose of topiramate. 

Topiramate may be affected by carbamazepine, hydantoins, metformin, and valproic acid. 

II.e. 5.2. Interactions between first and second generation AEDs. Felbamate raises plasma concentrations of phenytoin, valproic acid and carbamazepine. Clearance of tiagabine, topiramate and zon-isamide is increased in the presence of an enzyme inducer. Vigabatrin reduces phenytoin concentrations after 4-5 weeks of comedication (via an unknown mechanism). For tiagabine, the elimination half-life may be reduced by 2-3 hours in the presence of an enzyme-induction AED. Lamotrigine elimination is slower if given with valproic acid. Topiramate reduces elimination of phenytoin. 

With the exception of topiramate (which also requires a high-dose oestroprogestogen), second generation AEDs are not considered to interfere with oestroprogestogen metabolism. The enzyme induction capacity of oxcarbazepine is much weaker than that of carbamazepine. 

Other agents with anticonvulsant properties that may be of use m the treatment of bipolar disorder include topiramate, gabapentin, tiagabine and carbamazepine (Janicak et al., 2001). 

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