Felbamate Lamotrigine

Drugs that may affect valproic acid include carbamazepine, charcoal, chlorpromazine, cholestyramine, cimetidine, erythromycin, ethosuximide, felbamate, lamotrigine, phenytoin, rifampin, and salicylates. Drugs that may be affected by valproic acid include carbamazepine, clonazepam, diazepam, ethosuximide, lamotrigine, phenobarbital, phenytoin, tolbutamide, tricyclic antidepressants, warfarin, and zidovudine. 

Neither vigabatrin nor gabapentin caused porphyrin accumulation in chicken embryo cultured liver cells, whereas felbamate, lamotrigine, and tiagabine were por-phyrinogenic in this model (129). For gabapentin, safety in porphyrias has been confirmed in preliminary clinical observations (SEDA-19, 70) (SEDA-20, 62). 

For atypical absence, tonic and clonic seizures, first line treatment is with valproate and second line with acetazolamide, carbamazepine, clobazam, clonazepam, ethosuximide, felbamate, lamotrigine, oxacarbamazepine, phenobarbitone, phenytoin, primidone or topiramate. 

Phenobarbital Phenytoin Primidone Felbamate Lamotrigine Tiagabide Topiramate Valproate Zonisamide Clobazam Clonazepam Diazepam usually compensated by the effect of the added drug risk of toxicity when interfering drug is discontinued drug... 

Valproate Carbamazepine epoxide Diazepam Felbamate Lamotrigine Phenobarbital Risk of toxicity, particularly with phenobarbital including primidone-derived phenobarbital and lamotrigine Inhibition of metabolism of the affected drug. Valproate also displaces diazepam from protein binding sites, affecting relation between total diazepam concentration and effect... 

Lennox-Gastaut syndrome is a mixed seizure disorder combining the atypical absence seizures with tonic, tonic-clonic, or myoclonic motor patterns. The syndrome begins in childhood and usually Includes mental retardation. Although adequate control of the seizures rarely Is achieved, valproate, phenytoin, felbamate, lamotrigine, topiramate, and clonazepam have been... 

Attaining good control of tonic or atonic seizures Is difficult. Valproate, felbamate, lamotrigine, benzodiazepines, and topiramate have proven to be effective in some individuals. 

Therefore, plasma concentrations for drugs metabolized by these isoforms will be affected (see Chapter 10). Thus, the addition of phenytoin to an AED regimen can reduce their plasma levels by inducing their CYP3A4 metabolism for carbamazepine, felbamate, lamotrigine, oxcarbazepine, tiagabine, valproate, and zonisamide. Other drugs for which metabolism is induced by phenytoin include methadone, theophylline, warfarin, and oral contraceptives. On the other hand, plasma phenytoin levels are increased by carbamazepine, felbamate, cimetidine, warfarin, chloramphenicol, isoniazid, and disulfiram. Plasma phenytoin levels are decreased by rifampin, antacids, and valproate (free phenytoin levels remain the same). 

Carbamazepine, felbamate, lamotrigine, oxcarbazepine, phenytoin, topiramate, zonisamide... 

A method for the analysis of the basic antiepileptic compounds felbamate, lamotrigine, carbamazepine, carbamazepine-10,11-epoxide, gabapentin, pregabalin, levetiracetam, and oxcarbazepine monohydroxy derivative (oxcarb MHD) in human plasma is described. This protocol incorporates a simplified sample preparation step followed by quantitative high performance chromatography-tandem mass spectrometry detection of commonly prescribed and monitored anticonvulsant drugs. Since polytherapy is common in epilepsy patients, use of a multiconstituent assay can improve laboratory efficiency and reduce required analytical time. 

The newer AEDs were first approved as adjunctive therapy for patients with refractory partial seizures. To date, lamotrigine, topiramate, and oxcarbazepine have received FDA approval for use in monotherapy in patients with partial seizures. Felbamate has monotherapy approval but causes significant side effects. 

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. 

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. 

Type I Block SRF by enhancing sodium channel inactivation Phenytoin Carbamazepine Oxcarbazepine Lamotrigine Felbamate ... 

Curry, W.J. and Kulling, D.L. (1998) Newer antiepileptic drugs ga-bapentin, lamotrigine, felbamate, topiramate and fosphenytoin. Am Fam Physician 57 513-520. 

Phenobarbital Enhances phasic GABAa receptor responses reduces excitatory synaptic responses Nearly complete absorption not significantly bound to plasma proteins peak concentrations in Vi to 4 h no active metabolites tjy2 varies from 75 to 125 h Generalized tonic-clonic seizures, partial seizures, myoclonic seizures, generalized seizures, neonatal seizures, status epilepticus Toxicity Sedation, cognitive issues, ataxia, hyperactivity Interactions Valproate, carbamazepine, felbamate, phenytoin, cyclosporine, felodipine, lamotrigine, nifedipine, nimodipine, steroids, theophylline, verapamil, others... 

Potschka, H., M. Fedrowitz, and W. Loscher. 2002. P-Glycoprotein-mediated efflux of phenobar-bital, lamotrigine, and felbamate at the blood-brain barrier Evidence from microdialysis experiments in rats. Neurosci Lett 327 173. 

Partial seizures Carbamazepine Phenytoin Lamotrigine Valproic acid Oxcarbazepine Gabapentin Topiramate Levetiracetam Zonisamide Tiagabine Primidone, phenobarbital Felbamate... 

Myoclonic Valproic acid, clonazepam Lamotrigine, topiramate, felbamate... 

For simple and complex partial seizures and secondary generalized tonic-clonic seizures, the first line drugs are - carbamazepine, valproate and phenytoin. Second line drugs include - acetazolamide, clobazam, clonazepam, ethosuximide, felbamate, gabapentin, lamotrigine, levetiracetam, oxacarbamazepine, primidone, tiagabine, topiramate and vigabactin. 

In addition to phenytoin, carbamazepine, and lamotrigine, metabolically optimized analogs of these drugs, such as fosphenytoin and oxcarbazepine, show clinical promise. Other anticonvulsants that block sodium channels, among several mechanisms of action, include zonisamide, felbamate, topiramate, and valproate (Fig. 5). 

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