Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vigabatrin (gamma-vinyl-GABA), an irreversible inhibitor of gamma-aminobutyric acid transaminase, has been reported to be effective in the treatment of refractory epilepsies. Animal toxicology studies have shown that long-term application of vigabatrin induces intramyelinic edema and microvacuolation of the white matter in non-primate species. However, clinical and neuropathological studies of patients exposed to long-term vigabatrin treatment have, so far, provided no evidence for microvacuolation in the human brain. We report on the histopathological findings of selective amygdalohippocampectomy specimens from a 36-year-old female patient treated with vigabatrin for a period of 11.5 months, and from 2 control patients with chronic refractory temporal lobe seizures. All specimens showed changes associated with chronic epileptic seizures including focal neuronal loss and hippocampal gliosis. Microvacuoles, intramyelinic edema or other manifestations of neurotoxic damage were not observed in vigabatrin exposed tissue, supporting the view that this compound may not exert hippocampal neurotoxicity in humans.
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PMID:Neuropathology of a human hippocampus following long-term treatment with vigabatrin: lack of microvacuoles. 238 87

1. Gamma-vinyl GABA (GVG) is a new anticonvulsant drug that enhances levels of GABA in the brain by irreversibly inhibiting GABA transaminase. 2. To further evaluate the effects and mechanism of action of GVG in the human brain, we measured acetylcholinesterase (AChE) activity and levels of homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), cyclic nucleotides (cAMP, cGMP), total GABA (TGABA), and GVG in CSF of 78 patients with complex partial epilepsy. The CSF samples were taken at baseline and after 3 months of GVG administration (3 g GVG per day). Thereafter, the responders (= 50% decrease in number of seizures) were divided (double-blind) into two groups that received either 1.5 g or 3 g of GVG per day for the next 3 months. The third CSF sample was taken after this double-blind period. 3. TGABA levels were increased during the GVG treatment (p less than 0.001). In the whole group of patients AChE, HVA, 5-HIAA, and cAMP did not differ from baseline values, cGMP levels were slightly elevated after 3 months of GVG administration (p = 0.019), but were no longer elevated after 6 months. Responders had slightly lower AChE activity than nonresponders (p = 0.041). After 6 months of drug treatment the cGMP levels of patients receiving 1.5 g of GVG did not differ from those receiving 3 g. 4. In conclusion, GVG administration elevates levels of TGABA in the CSF without any clear of constant change to cholinergic and aminergic transmission or effect on cyclic nucleotides. Our study further emphasizes the specific mechanism of action of GVG via GABAergic transmission.
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PMID:Effect of gamma-vinyl GABA treatment on cholinergic and aminergic neurotransmission and on cyclic nucleotides in human complex partial epilepsy--a CSF study. 245 56

Sixty-one pediatric patients (12-229 months of age) with refractory epilepsy were treated with vigabatrin [gamma-vinyl GABA (GVG)] in a 16-week, single-blind, add-on, placebo-controlled trial. Twenty-three patients (38%) showed a reduction of more than 50% in seizure frequency; 12 patients (20%) experienced a seizure increase; and the remaining 26 did not show significant differences between placebo and GVG treatment. Among the 216 patients who entered the long-term phase after having experienced more than 50% decrease in seizure frequency, 14 continued with the same degree of improvement after 2-11 months of follow-up (mean 7.7). GVG was particularly efficient in cryptogenic partial epilepsy. Conversely, nonprogressive myoclonic epilepsy tended to be aggravated. Agitation was the most commonly observed side effect, mainly at onset of therapy in mentally retarded patients, but was easily reversed by dose reduction. GVG is a promising drug in the treatment of refractory epilepsies of childhood.
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PMID:Vigabatrin in the treatment of childhood epilepsies: a single-blind placebo-controlled study. 250 84

GABA transmission plays a key role in controlling seizure activity. The precise nature of its effect depends on the particular location in the brain and the pathway involved. Animal studies have helped to define specific brain regions such as the substantia nigra and area tempestas that are critical in controlling seizure activity. Antiepileptic drugs such as vigabatrin [gamma vinyl GABA (GVG)], a drug rationally developed to treat resistant epilepsy, can enhance GABA transmission in these regions and may thereby afford seizure protection.
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PMID:GABA in epilepsy: the pharmacologic basis. 254 36

The Lennox-Gastaut Syndrome is one of the most refractory form of epilepsy and a variety of compounds, such as traditional antiepileptics, "new anticonvulsants" and non-anticonvulsant drugs has been tested. ACTH and, among the traditional antiepileptics. Clonazepam and Sodium Valproate showed the most favorable effects. The immediate (within 6 months) therapeutic response to ACTH and Clonazepam is satisfactory, with a more than 50% reduction of seizures in about one half of patients; after one year, however, only a small percentage of cases (7-10%), rather close to that with spontaneous remission, shows some therapeutic benefit. Valproate, when used as a single drug, produces a decrease in seizures (greater than 50%) in 25-30% of pts. A list of compounds, such as amphetamine, taurine, amantadine, allopurinol and, among the new putative antiepileptics, cinromide and gamma-vinyl-GABA, has been tested with some occasionally observed improvement in seizure control. None of these compounds, however, is of really proven efficacy. An acquired general rule of treatment is to avoid complex polypharmacy and overdose; there is in fact good evidence that making the child drowsy will greatly increase the number of fits.
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PMID:[Lennox-Gestaut syndrome: therapeutic aspects]. 270 Aug 41

The effects of three drugs, namely gamma-vinyl GABA (vigabatrin), gamma-acetylenic GABA, and aminooxyacetic acid, which increase brain GABA concentrations by irreversible inhibition of GABA degradation, were studied in amygdala-kindled rats. Vigabatrin 800 or 1,200 mg/kg i.p. 4 h after its administration, caused prolongation of behavioural seizures and electrographic afterdischarges recorded from the stimulated amygdala. One to three days after administration it dose dependently reduced seizure severity, seizure duration and afterdischarge duration in most animals. Determination of GABA levels in synaptosomes isolated from 12 brain regions of kindled rats 4 or 48 h after injection of 1,200 mg/kg vigabatrin indicated that the variable effects of this drug at different times after its administration could be related to differences in the time course of nerve terminal GABA increases in selective brain regions such as amygdala and corpus striatum. In contrast to vigabatrin, gamma-acetylenic GABA, 100 mg/kg i.p., reduced seizure severity in kindled rats as early as 4 h after its administration but afterdischarge duration increased significantly on subsequent days. Similar late increases in afterdischarge duration (and limbic seizure activity) after the time of maximum anticonvulsant effect had elapsed were also observed with vigabatrin, which could suggest that the anticonvulsant effect of such drugs is followed by withdrawal hyperexcitability. Aminooxyacetic acid, 20 mg/kg i.p., exerted no significant anticonvulsant effect in kindled rats but prolonged afterdischarge duration in several of the animals studied. The data suggest that GABA-T inhibitors, such as vigabatrin, differ from most antiepileptic drugs previously tested in the kindling model in that they may produce both anticonvulsant and proconvulsant effects at the same dose in the same animal as a function of time after administration.
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PMID:Anticonvulsant and proconvulsant effects of inhibitors of GABA degradation in the amygdala-kindling model. 274 84

This study better defines the way in which the thalamus controls expression of experimental generalized seizures. The effects of small intrathalamic injections of the direct GABA agonist muscimol on the thresholds of pentylenetetrazol (PTZ)-induced seizures and on spontaneous behavior were determined in the rat and compared with the effects of injections of gamma-vinyl-GABA (GVG), an irreversible inhibitor of GABA transaminase. Muscimol injections produced neuronal inhibition in a relatively small area of thalamus, whereas GVG injections produced inhibition in a much larger area. Muscimol injections in the midline thalamus in the vicinity of the paraventricular, paratenial, interanteromedial, intermediodorsal, and central medial nuclei facilitated PTZ myoclonic and clonic seizures and also produced sedation. These effects on seizure thresholds were attributable both to a lower PTZ threshold dose for initiation of electroencephalographic (EEG) seizure activity and to an increased probability of this EEG activity being expressed as behavioral seizures. Midline injections located more posteriorly in the thalamus also inhibited tonic seizures. Muscimol injections placed laterally, dorsally, or ventrally to this midline thalamic region had much less effect on behavior or seizures. In contrast, GVG injections in the anterior medial thalamus elevated the threshold for all PTZ seizure types and for associated EEG seizure activity but had little effect on spontaneous behavior. These findings demonstrate the existence of an important seizure regulatory system in the midline of the thalamus and a direct anatomic link between the mechanisms for regulating arousal and seizure production which may help explain the association between sleep and seizure facilitation in humans.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of a median thalamic system regulating seizures and arousal. 275 1

1. The anticonvulsant potency of vigabatrin (gamma-vinyl GABA, GVG) was studied in an open trial in a group of 21 mentally handicapped patients with drug-resistant epilepsy. 2. With this treatment one third of these patients had more than 50% reduction in seizure frequency. The anticonvulsant effect appeared during the first month of therapy and was maintained during a 7-month study. The side effects were mild: mainly tiredness, aggressiveness, and ataxia. Other anticonvulsant drugs remained at baseline levels during GVG therapy. GVG was not found to modulate EEG recordings. 3. According to our results, GVG is effective for treating intractable epilepsy in mentally handicapped patients.
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PMID:Vigabatrin in epilepsy in mentally retarded patients. 275 2

1. To evaluate the relationship between the clinical response and enhancement of GABAergic neurotransmission, for 6 months we administered vigabatrin (gamma-vinyl-GABA, GVG) to 75 patients with complex partial epilepsy. Total GABA (TGABA), free GABA (FGABA), homocarnosine (HC), and GVG concentrations were measured in CSF of these patients before and during GVG treatment. 2. Over 50% reduction in seizures was found in 55% of the patients. Dose-reduction resulted in a relapse, i.e. the return of seizures. 3. At baseline TGABA, FGABA, and HC did not differ in responders and nonresponders. After GVG treatment, the TGABA and HC levels were lower in nonresponders (P less than 0.001), but the GVG and FGABA levels did not differ. The GVG dose reduction resulted in a concomitant decrease in TGABA, FGABA, HC and GVG (P less than 0.001). 4. According to our results GVG is an effective anticonvulsant drug in complex partial seizures. In nonresponders the poor anticonvulsant response may be related to the lower elevation of the CSF markers of GABAergic neuronal activity in this group compared with the responders.
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PMID:Cerebrospinal fluid GABA and seizure control with vigabatrin. 275 14

In studies spanning more than 5 years, more than 1,100 patients with epilepsy have been treated with vigabatrin (gamma vinyl GABA, GVG). Sixty-two patients with partial seizures with secondary generalization took part in this trial: 41 patients continued in the trial after 19 months of treatment. After 36 months, the median percentage of baseline seizures was less than 20%. GVG is a very potent antiepileptic drug. It is well tolerated in humans. The side effects are few. Skin rash and other allergic reactions have rarely been seen. Tolerance to the sedative effect is in contrast to the lack of tolerance to the anti-epileptic effect.
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PMID:Long-term evaluation of vigabatrin (gamma vinyl GABA) in epilepsy. 276 17


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