Vigabatrin Carbamazepine

Arndt CF, Salle M, Derambure PH, Defoort-Dhellemmes S, Hache JC. The effect on vision of associated treatments in patients taking vigabatrin carbamazepine versus valproate. Epilepsia 2002 43(8) 812-17. 

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

Antiepileptics Phenytoin Carbamazepine Valproic acid Gabapentin Vigabatrin Ethosuximide Benzodiazepines... 

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

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. 

Changes in body weight associated with anticonvulsants have been reviewed (116), including the effects of the antiepileptic drugs that have been most commonly associated with this adverse effect (valproic acid, carbamazepine, vigabatrin, and gabapentin) (117). Unlike most anticonvulsants, topiramate, felbamate, and zonisamide can cause weight loss. 

Should certain antiepileptic drugs be contraindicated in patients with active psychosis Unfortunately there is not enough solid information to answer this question. Undoubtedly, anticonvulsants that are less likely to cause psychosis (lamotrigine, carbamazepine, oxcarbaze-pine, valproate) should be preferred (52,53). However, patients with psychoses have been successfully treated even with drugs that are believed to be associated with psychosis, such as vigabatrin. For example, in a prospective study in 10 patients with psychosis and epilepsy to whom vigabatrin was added, there was no aggravation of the psychiatric disorder (54). 

Individual drugs carbamazepine, phenytoin, sodium valproate, lamotrigine, vigabatrin, gabapentin, clonazepam, topiramate, levetiracetam. 

Bromide (1857) was the first drug to be used for the treatment of epilepsy, but it is now obsolete. Phenobarbital, introduced in 1912, controlled patients resistant to bromides. The next success was the discovery in 1938 of phenytoin (a hydantoin) which is structurally related to the barbiturates. Since then many other drugs have been discovered, but phenytoin still remains a drug of choice in the treatment of major epilepsy. Over the past ten years there has been a dramatic increase in the number of new anticonvulsant drugs (vigabatrin, gabapentin, lamotrigine, topiramate, oxcarbazepine, levetiracetam), but none has been shown to be superior to the major standard anticonvulsants (phenytoin, carbamazepine and sodium valproate). 

Visual field defects associated with various antiepUeptic drugs (carbamazepine, diazepam, gabapentin, pheny-toin, tiagabine, and vigabatrin) have been reviewed (19). The true frequency is unknown, but in a retrospective study in 158 patients with partial epilepsy visual field defects were detected in 21 (13%) 13 patients had concentric visual field constriction without subjective spontaneous manifestations. Of these 13 patients, 9 were taking vigabatrin. 

Alopecia is not uncommon with valproate, and it can also occasionally occur with phenjdoin, carbamazepine, vigabatrin, and gabapentin. 

Nousiainen I, Kalviainen R, Mantyjarvi M. Color vision in epilepsy patients treated with vigabatrin or carbamazepine monotherapy. Ophthalmology 2000 107(5) 884-8. 

In a randomized open comparison of carbamazepine and vigabatrin in newly diagnosed epilepsy (6), patients randomized to vigabatrin reported less frequent drowsiness (44 versus 62%) and dizziness (7 versus 20%), and more frequent myoclonic jerks (14 versus 2%) and visual scintillae (16 versus 0%). 

One report suggesting that carbamazepine reduces serum vigabatrin concentrations (SEDA-21, 80) requires confirmation. 

Although vigabatrin is not metabolized by liver enzymes it increased serum carbamazepine concentrations by at least 10% in 66 epileptic patients aged 10-66 years with focal seizure onset with or without secondary generalization (74). 

Kalviainen R, Aikia M, Saukkonen AM, Mervaala E, Riekkinen PJ Sr. Vigabatrin vs carbamazepine... 

Kalviainen R, Nousianen I, Nikoskelainen A, Partanen J, Partanen K, Mantijarvi M, Riekkinen PJ. Visual field defects associated with initial vigabatrin monotherapy as compared with initial carbamazepine monotherapy. Epilepsia 1998 39(Suppl. 2) 5. 

Mecarelli O, Rinalduzzi S, Accornero N. Changes in color vision after a single dose of vigabatrin or carbamazepine in healthy volunteers. Clin Neuropharmacol 2001 24(l) 23-6. 

Jedrzejczak J, Dlawichowska E, Owczarek K, Majkowski J. Effect of vigabatrin addition on carbamazepine blood serum levels in patients with epilepsy. Epilepsy Res 2000 39(2) 115-20. 

Clinically important, potentially hazardous interactions with carbamazepine, lamotrigine, phenobarbital, primidone, topiramate, valproic acid, vigabatrin... 

Importantly, Loscher et al. found that carbamazepine, felbamate, gabapentin, lamotrigine, phenobarbital, and topiramate are substrates of ABCBl (P-gp) [38]. Crowe et al. also studied the transport of a variety of antiepileptic drugs including vigabatrin, gabapentin, phenobarbitone, lamotrigine, phenytoin, carbamazepine, and acetazolamide in colorectal tumor-derived Caco-2 cell monolayers. They found that only one antiepileptic, acetazolamide, is a weak ABCBl substrate [39]. 

Barbiturates phenobarbital 1 Benzodiazepines alprazolam, diazepam, i lorazepam, oxazepam Carbamazepine, ethosuximide, valproic acid, phenytoin, diazepam, lorazepam, gabapentin, lamotrigine, felbamate, topiramate, tiagabin, vigabatrin... 

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