Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gabapentin is an antiepileptic drug with an unknown mechanism of action apparently dissimilar to that of other antiepileptic agents, and possessing some desirable pharmacokinetic traits. The drug is not protein bound, is not metabolised and does not induce liver enzymes, diminishing the likelihood of drug interactions with other antiepileptic agents and drugs such as oral contraceptives. Although gabapentin is a structural analogue of the neurotransmitter gamma-aminobutyric acid (GABA), which does not cross the blood-brain barrier, gabapentin penetrates into the CNS and its activity is seemingly distinct from GABA-related effects. Present clinical evaluation is largely restricted to proof of efficacy trials of gabapentin as add-on therapy in patients with partial epilepsy resistant to conventional treatment. Gabapentin (usually 600 to 1800 mg/day) provides notable benefit, reducing seizure frequency by > or = 50% in 18 to 28% of patients with refractory partial seizures, as shown in 3 double-blind, placebo-controlled trials. Overall, seizure frequency decreased by 18 to 32% during 3-month treatment periods. Patients with complex partial seizures, and partial seizures secondarily generalised, are particularly likely to respond to gabapentin. Current experience with the drug in other seizure types, and as monotherapy, is limited. Mild adverse events, commonly somnolence, fatigue, ataxia and dizziness, have been reported in about 75% of gabapentin recipients. While the drug has been well tolerated when administered to a few patients for periods of up to 5 years, its long term tolerability profile has yet to be fully expounded. Thus, with its favourable pharmacokinetic profile, and efficacy in some refractory patients, gabapentin is poised to fill a niche as an adjunct to the treatment of partial epilepsy. Promising results obtained thus far warrant further work to clarify its long term tolerability, its possible efficacy in other seizure types, its position relative to other agents and its use as monotherapy. In the meantime, gabapentin is likely to provide a much-needed option in a therapeutic area requiring complex management.
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PMID:Gabapentin. A review of its pharmacological properties and clinical potential in epilepsy. 769 32

This is the 2-year interim report of results from a multicenter, open-label study evaluating the long-term efficacy and safety of gabapentin (Neurontin) as add-on therapy in patients with refractory partial seizures who had had a therapeutic response to gabapentin in a preceding 12-week double-blind trial or 12-week open-label extension. A total of 240 patients continued to receive gabapentin as add-on therapy at dosages of 600-2400 mg/day for an average of 342 days (range 10-784 days). Efficacy analyses compared seizure frequency during consecutive 12-week treatment periods with seizure frequency during the 12-week baseline. During the nine treatment periods evaluated, the percent of patients with a 50% or greater reduction in seizure frequency ranged from 35% to 71%, and the median percent change in seizure frequency ranged from -33% to -60%. At the time of data cutoff, 30% of patients had withdrawn from the study due to lack of efficacy, and 4% due to adverse events. In 225 patient-years of gabapentin treatment in this study, CNS adverse events reported by more than 10% of patients were nystagmus, somnolence, diplopia, tremor, ataxia, and dizziness. No consistent changes in clinical laboratory values were associated with gabapentin. Gabapentin as add-on therapy at dosages up to 2400 mg/day is safe during long-term treatment in patients with refractory partial seizures. Subgroup analyses of patients who remained in the study over the long term confirmed that gabapentin maintained efficacy for up to 2 years.
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PMID:The long-term safety and efficacy of gabapentin (Neurontin) as add-on therapy in drug-resistant partial epilepsy. The US Gabapentin Study Group. 808 58

Gabapentin has been accepted worldwide as a novel antiepileptic drug with a favourable tolerability profile. However, movement disorders have been reported previously as rare side-effects in individual patients. We report on two patients who developed isolated severe ataxia under low-dose gabapentin which resolved abruptly after discontinuation of the drug. This side-effect probably resembled a rare idiosyncratic adverse reaction. We propose the gabapentin-specific neuronal binding site which has a high density in the cerebellum as a possible mechanism of action and suggest that the initiation of gabapentin requires caution if pre-existing cerebellar function impairment is evident.
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PMID:Isolated ataxia as an idiosyncratic side-effect under gabapentin. 953 Sep 50

With the aim to evaluate the clinical efficacy and tolerability of gabapentin as an adjuvant therapy in patients with refractory partial epilepsy we conducted an open-randomized study, with 12-weeks follow-up period. The study included 18 epilepsy patients with unsatisfactorily controlled seizures, in spite of the treatment with 1 or 2 first line antiepileptic drug. Gabapentin was administered in a total daily dose between 900-1200 mg. Our results showed seizure frequency reduction by more than 50% in 72.2% patients, while the most frequent adverse effects were vertigo (16.67%) and ataxia (11.11%).
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PMID:[Gabapentin as adjuvant therapy in the treatment of refractory partial epilepsy]. 1043 20

Gabapentin (GBP) is a antiepileptic drug (AED) indicated as adjunct therapy for treatment of partial seizures, with and without secondary generalization, in patients 12 and older with epilepsy. GBP (1-(aminomethyl) cyclohexaneacetic acid) is structurally related to gamma-aminobutyric acid (GABA), which readily crosses the blood-brain barrier. Radiolabeled GBP binds throughout the central nervous system in anatomic areas important in treatment of seizures. Its precise mechanism of action is unknown. An open-label, dose-ranging study of doses up to 1,800 mg produced > or =50% seizure reductions [responder rate (RR)] in 29% of patients with partial seizures. Three double-blind, placebo-controlled, parallel add-on trials at doses of 300-1,800 mg have produced RR of up to 28%, with a placebo RR of 8-10%. An active controlled, parallel group comparison of 600 mg to 2,400 mg in monotherapy conversion design showed no significant difference among the 600 mg, 1,200 mg, and 2,400 mg groups compared to a placebo group. An inpatient, active-controlled comparison of 300 mg and 3,600 mg in a parallel-design monotherapy trial showed that time to exit from the study was significantly longer for the 3,600-mg group and the completion rate significantly higher (53% vs. 17%) for patients receiving 3,600 mg/day vs. 300 mg/day of GBP. Successful double-blind, placebo-controlled trials in refractory childhood partial seizures and benign childhood epilepsy with centrotemporal spikes have been recently concluded. Absence was not successfully treated in one small double-blind trial. Open-label reports emphasize adjustments of patients to higher doses than those indicated in the package labeling. An open-label trial of GBP therapy in patients with partial seizures (n = 2,216) produced progressively greater seizure freedom rates as patients were titrated from > or =900 mg daily to > or = 1,800 mg daily (15.1% vs. 33.4%), with a similar effect on RR (18.1% vs. 44.9%). An add-on, open-label study treating partial seizures (n = 141) reported an RR of 71%, with 46% seizure-free in the last 8 weeks of treatment and doses up to 2,400 mg daily. A comparison trial of three doses of GBP to 600 mg of carbamazepine showed similar retention rates for 1,800 mg of GBP and 600 mg of CBZ. Another study reported 48% of patients experiencing 50% reduction, nine of whom had doses greater than 2,400 mg. Treatment in children has reported a 34.4% RR in 32 children with refractory partial seizures. A French open-label adjunctive trial documented a 33.9% RR; 13.4% were seizure-free during the evaluation period. Adverse experiences most commonly noted included somnolence, dizziness, and ataxia. Weight gain was sometimes reported with higher doses of GBP, and pediatric reports cite prominent behavioral changes, including hyperactivity, irritability, and agitation. GBP appears best used at doses at and potentially above those suggested in its package labeling. Although efficacy occurs at lower levels, increased GBP doses are associated with additional efficacy. Reports suggest that initiation at 2,400 mg or 3,600 mg may not be associated with increased adverse experiences. Titration to 900 or 1,200 mg on the first day of GBP therapy appear to be well tolerated.
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PMID:Gabapentin. 1053 Jun 96

Gabapentin, which has been approved for add-on therapy of focal seizures, is increasingly used for treatment of neuropathic pain. Its analgesic effect is supposed to be due to reduction of glutamatergic transmission, improvement of GABAergic transmission and to binding to voltage-dependent calcium channels. Experimental studies demonstrated an ameliorating effect of gabapentin on neuropathic pain. Placebo-controlled studies revealed an efficacy of gabapentin against pain in diabetic neuropathy and postherpetic neuralgia and in prophylaxis of migraine. Case reports show an analgesic effect of gabapentin in trigeminus neuralgia and in reflex sympathetic dystrophy. The main adverse events are dizziness, ataxia and somnolence. Controlled studies, which compare the efficacy of gabapentin with that of the respective reference drug, are needed to evaluate its importance in treatment of pain.
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PMID:[Gabapentin therapy for pain]. 1125 57

Gabapentin, which has been approved for add-on therapy of focal seizures, is increasingly used for treatment of neuropathic pain. Its analgesic effect is supposed to be due to reduction of glutamatergic transmission, improvement of GABAergic transmission and to binding to voltage-dependent calcium channels. Experimental studies demonstrated an ameliorating effect of gabapentin on neuropathic pain. Placebo-controlled studies revealed an efficacy of gabapentin against pain in diabetic neuropathy and postherpetic neuralgia and in prophylaxis of migraine. Case reports show an analgesic effect of gabapentin in trigeminus neuralgia and in reflex sympathetic dystrophy. The main adverse events are dizziness, ataxia and somnolence. Controlled studies, which compare the efficacy of gabapentin with that of the respective reference drug, are needed to evaluate its importance in treatment of pain.
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PMID:[Gabapentin for therapy of neuropathic pain]. 1181 Mar 68

The aim of this work was to investigate the efficacy of the GABAergic drug gabapentin in the treatment of the cerebellar signs caused by cortical cerebellar atrophy (CCA). Ten patients with CCA received gabapentin in single doses of 400 mg in an open-label study; thereafter, daily administration of 900-1,600 mg of gabapentin was continued during at least 4 weeks. An ataxia scale based on clinical findings was used to evaluate the cerebellar signs at baseline and after administration of the drug. A statistically significant improvement of the ataxia scores was found after single doses of 400 mg of gabapentin and after the administration of 900-1,600 mg of this drug during 4 weeks, as compared to the results obtained at baseline. An important clinical amelioration was also evident. Gabapentin has been demonstrated to be capable of improving the cerebellar signs in cases of CCA, after single doses and after continued administration of the drug during 4 weeks. GABAergic enhancement or supplementation could play an important role in the treatment of diseases of the cerebellar cortex associated with a deficit of GABA.
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PMID:Treatment of ataxia in cortical cerebellar atrophy with the GABAergic drug gabapentin. A preliminary study. 1521 38

Gabapentin is an antiepileptic medication that also has been used for restless legs syndrome. The mechanism of action is unknown. The most commonly reported adverse effects of this medication include somnolence, dizziness, ataxia, fatigue, nystagmus, and tremor. Myalgia has been reported in 2% of gabapentin users compared with 1.9% of patients in placebo-controlled add-on trials. Two patients on short daily hemodialysis therapy developed neuromuscular symptoms and an elevation in creatine kinase levels after starting gabapentin therapy. To our knowledge, this is the first case report of an increase in creatine kinase level after the administration of gabapentin.
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PMID:Gabapentin-induced myopathy in 2 patients on short daily hemodialysis. 1595 20

Voltage-dependent calcium channels (VDCCs) are heteromultimeric complexes that mediate calcium influx into cells in response to changes in membrane potential. The alpha1A subunit, encoded by the CACNA1A gene, is the pore-forming subunit specific to the neuronal P/Q-type VDCCs. These are implicated in fast excitatory and inhibitory neurotransmission. Their highest levels of expression are found in the Purkinje cell layer of the cerebellum, and in the hippocampus. Spinocerebellar ataxia type 6 (SCA 6) is an autosomal dominant cerebellar degeneration that shares neuropathological findings with late-onset cortical cerebellar atrophy (CCA). It is caused by an abnormal expansion of a trinucleotide (CAG) repeat in exon 47 of CACNA1A, on chromosome 19p13. This translates into a polyglutamine (polyQ) tract of prolonged length in the carboxyl terminal of the alpha1A subunit. Heterologous expression of mutated alpha1A subunits results in increased channel inactivation in electrophysiological tests. No treatment is known to improve SCA 6 at present, as none of the available drugs is able to reverse alpha1A dysregulation, nor disturbed protein aggregation, transport and localization in this disease. The drugs gabapentin and pregabalin interact with the alpha2delta subunit of the P/Q-type VDCCs. Gabapentin and pregabalin slow the rate of inactivation in recombinant P/Q-type VDCCs, expressed in Xenopus oocytes. These drugs improve ataxia in cases of CCA, olivopontocerebellar atrophy and ataxia-telangiectasia. On the basis of the neuropathological identity of SCA 6 with CCA, and given the capacity of gabapentin and pregabalin to decrease P/Q-type VDCCs inactivation, in this paper the authors put forward the hypothesis that the administration of gabapentin and pregabalin might prove beneficial in SCA 6 as the ataxia caused by this disease would be expected to improve. The authors hope that researchers working with this illness will be inspired and encouraged to undertake the appropriate clinical and experimental work.
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PMID:The P/Q-type voltage-dependent calcium channel as pharmacological target in spinocerebellar ataxia type 6: gabapentin and pregabalin may be of therapeutic benefit. 1689 42


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