Gene/Protein Disease Symptom Drug Enzyme Compound
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 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Topiramate is a recently licensed and marketed antiepileptic drug in the UK for use as add-on therapy for refractory partial epilepsy. It has multiple modes of action involving voltage-dependent sodium channels, GABA receptors and glutamate receptors. Topiramate has very favourable pharmacokinetics as it is primarily excreted unchanged. Its metabolism is, however, increased by enzyme inducers, and it can inhibit the metabolism of phenytoin in some patients. Its efficacy as adjunctive treatment in refractory partial epilepsy in adults appears good, over 40% of patients have a 50% or greater reduction in seizure frequency when topiramate is added to their regime with up to 7% becoming seizure free. The main adverse events are ataxia, impaired concentration, confusion, dizziness, fatigue, parasthesia, somnolence and "thinking abnormal'. Most of these occurred during rapid titration. During long-term treatment, weight loss also occurred and nephrolithiasis occurred in 1.5% of patients receiving topiramate. Topiramate is a useful and well-tolerated addition to our treatment of refractory epilepsy, but it should be titrated slowly in order to avoid adverse events.
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PMID:Topiramate: a new antiepileptic drug for refractory epilepsy. 890 21

Topiramate is a new antiepileptic drug which has recently become available in the United States and in a number of European countries. Pharmacological studies suggest that its mode of action is multifactorial and involves blockade of voltage-dependent sodium channels, potentiation of GABAergic transmission and inhibition of excitatory pathways through an action at AMPA receptor sites. Carbonic anhydrase inhibiting properties have also been demonstrated but they are considered not to be relevant to anticonvulsant activity. Topiramate is well absorbed from the gastrointestinal tract, peak plasma levels being usually attained in 2-3 hours. The drug is negligibly (9-17%) bound to plasma proteins and is eliminated partly by renal excretion in unchanged form and partly by oxidation and hydrolysis. In healthy volunteers, the half-life is about 20-30 hours, but elimination rate is accelerated in patients taking concomitant enzyme inducing drugs such as phenytoin, carbamazepine and barbiturates. Topiramate has no major effects on plasma levels of concurrent anticonvulsants, except for a rise in plasma phenytoin in occasional patients. In double-blind add-on trials in refractory partial epilepsy, a significant reduction in seizure frequency has been demonstrated in over 40% of topiramate-treated patients (vs about 10% of those treated with placebo), a response rate which compares favourably with that observed with other new antiepileptic drugs. Dosages found to be effective in add-on controlled trials range between 200 and 1000 mg day-1, although most patients are likely to benefit from receiving 400 mg day-1 or less. Preliminary data suggest that topiramate may be effective also in generalized epilepsies, but this needs to be confirmed in prospective studies. The most common adverse effects of topiramate are CNS-related and include dizziness, fatigue, visual disturbances, ataxia, mental slowing and impaired concentration. Paresthesias, anorexia, weight loss and increased risk of nephrolithiasis have been also reported. Many of these effects are related to dose and/or to rate of dose titration. Based on these data, topiramate appears to be a valuable new drug, whose main current indication is in the add-on management of refractory partial and secondarily generalized seizures. Studies on its potential-value as monotherapy are in progress.
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PMID:A pharmacological and clinical review on topiramate, a new antiepileptic drug. 926 38

The pharmacokinetic and safety profile of topiramate as adjunctive therapy was assessed in pediatric patients with epilepsy in an open-label, 4-week, single-center study. Six children from each of the following age groups were enrolled: 4-7 years, 8-11 years, and 12-17 years. Patients received topiramate 1 mg/kg/day for 1 week, with subsequent progressive weekly increases in dosage to 3, 6, and then 9 mg/kg/day or 800 mg/day, whichever was less. Topiramate oral plasma clearance (CI/F) was independent of dose, and steady-state plasma concentrations increased in proportion to dose. Weight-normalized topiramate CL/F was higher (P = 0.003) in pediatric patients receiving enzyme-inducing concomitant antiepileptic drugs (AEDs) (mean = 70.1 ml/minute/70 kg) than in those not receiving enzyme-inducing AEDs (mean = 33.1 mL/ minute/kg). Topiramate CL/F in children was approximately 50% greater than that observed in adults regardless of the type of concomitant AED therapy. Thus steady-state plasma topiramate concentrations for the same mg/kg dose will be approximately 33% lower in pediatric patients than in adult patients. The most frequently reported treatment-emergent adverse events considered related to topiramate therapy included anorexia, fatigue, and nervousness, and no patient discontinued therapy. This study indicates that, in children 4-17 years of age, topiramate has linear pharmacokinetics, 50% higher clearance than in adults, and is generally well tolerated.
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PMID:A study of topiramate pharmacokinetics and tolerability in children with epilepsy. 1037 78

Six studies are cited to demonstrate that topiramate is effective as adjunctive therapy for refractory partial-onset seizures in adults. Subsequent studies indicate that topiramate is also effective as monotherapy in adults and as adjunctive therapy for partial-onset seizures in children, tonic-clonic seizures of nonfocal origin in children and adults, and drop attacks in Lennox-Gastaut syndrome. Adverse effects for adults and children included dizziness, fatigue, ataxia, confusion, somnolence, nephrolithiasis, paresthesia, and weight loss. More adverse effects were observed at higher doses. Topiramate exhibits rapid absorption, long duration of action, and minimal interaction with other antiepileptic drugs.
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PMID:Topiramate. 1053 Jun 97

Topiramate is a newly developed anticonvulsant agent with possible mood-stabilizing properties. Little is known about the short- and long-term effects of topiramate monotherapy in bipolar disorder. We here present the case of a 60-year-old female bipolar patient who received topiramate alone as maintenance treatment after recovering from euphoric mania. During 7 months, she was free from new manic symptomatology and she was able to reduce her overweight by 16.5 kg. The patient who is known to have a strongly hyperthymic temperament described symptoms of fatigue and sedation and eventually discontinued topiramate monotherapy. When she presented again in our bipolar clinic, severe euphoric mania had developed. After hospitalization, she slowly responded to oral sodium valproate loading plus zotepine. Her weight increased again and so did her triglyceride serum levels. Topiramate treatment and discontinuation did not seem to affect cholesterol serum levels.
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PMID:Topiramate monotherapy in the maintenance treatment of bipolar I disorder: effects on mood, weight and serum lipids. 1109 73

Topiramate (TPM) is a new anti-epileptic drug with proven efficacy against partial seizures in adults. Its use in children is less well documented. In a retrospective study, 41 patients with intractable childhood epilepsy were treated with TPM as add-on therapy for an average period of 15 months. They were classified according to seizure type and etiology. The dose was titrated for effect and ranged between 2 and 24 mg/kg/d. Of the 41 patients being treated, six became seizure free, ten had a seizure reduction of more than 75% and eight a seizure reduction of between 50 and 75%. The most remarkable effect was seen in seven patients with West syndrome. Of these, four patients became seizure free and one had more than 75% seizure reduction. Adverse effects including sedation, fatigue, difficulties with verbal expression and anorexia were noted in 15 patients. None of these effects were important enough to interrupt treatment. We conclude that TPM as adjunctive therapy is a promising drug in children with intractable epilepsy, especially in the patients with West syndrome.
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PMID:Retrospective study of topiramate in a paediatric population with intractable epilepsy showing promising effects in the West syndrome patients. 1181 66

Migraine is one of the leading causes of disability. Topiramate has multiple mechanisms and may reduce neurotransmission through the trigeminocervical complex to prevent migraine. In clinical trials for the prevention of migraine, the mean monthly migraine frequency decreased from 5.6 to 4.5 in the placebo group and larger decreases were observed with topiramate (100 mg/day, 5.8 to 3.5; 200 mg/day, 5.1 to 3.0). However, topiramate use is associated with a high incidence of adverse events (paraesthesia, fatigue, anorexia, diarrhoea), which may limit the willingness of patients to use topiramate for the prevention of migraine. BIBN 4096 BS is a non-peptide calcitonin gene-related peptide-receptor antagonist that has recently been trialled in migraine attacks. The primary efficacy end point was the reduction of severe or moderate headache prior to treatment to mild or no headache at 2 h. This endpoint was achieved in 21 of 32 (66%) patients with BIBN 4096 BS 2.5 mg, compared to 27% of patients given placebo. Although BIBN 4096 BS is a non-peptide, it is still administered intravenously, which will probably limit its use to medical centres.
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PMID:New drugs for the prevention and treatment of migraine: topiramate and BIBN 4096 BS. 1501 83

(1) Topiramate carries a dose-dependent risk of severe metabolic acidosis in adults and children. (2) Various situations increase the risk, including diarrhea, respiratory disorders and surgery. (3) Loss of appetite, fatigue and hyperventilation are warning signs.
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PMID:Metabolic acidosis due to topiramate. 1549 1

The efficacy of topiramate in migraine prevention (prophylaxis) was established in two multicenter, randomized, double-blind, placebo-controlled, pivotal trials. Topiramate has received regulatory approval for use in adults for migraine prophylaxis (prevention) in the US and numerous other countries, including France, Ireland, Switzerland, Brazil, Taiwan, Spain, and Australia. Treatment with 100 or 200 mg per day of topiramate was associated with significant reductions in the frequency of migraine headaches, number of migraine days, and use of acute medications. No increase in efficacy was observed between 100 and 200 mg per day of topiramate. Based on efficacy and tolerability, 100 mg per day of topiramate should be the initial target dose for most patients. The most common adverse events were paresthesia, fatigue, decreased appetite, nausea, diarrhea, weight decrease, and taste perversion. Topiramate is a first-line migraine preventive drug and should especially be considered as a preferred treatment for all patients who are concerned about gaining weight, who are currently overweight, or who have coexisting epilepsy.
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PMID:Topiramate in migraine prevention. 1583 91

When treating patients with migraine, clinicians should consider prescribing appropriate combinations of acute and preventive therapies. An effective migraine-preventive therapy should be prescribed to patients with frequent (> or = 2 migraines per month) or severe migraine. Topiramate has been shown to be an effective and generally well-tolerated migraine prophylaxis (preventive) therapy in adults, as demonstrated in several large, controlled trials. The most common adverse events in these trials were paresthesia, fatigue, anorexia, nausea, taste alteration, and diarrhea. Most adverse events were mild to moderate and transient in nature. Although patients should take migraine-preventive medications for approximately 2 to 3 months before evaluating effect, topiramate has shown efficacy as early as the first month of treatment. This article describes "real-world" approaches to using topiramate as a migraine-preventive therapy. Topiramate has received regulatory approval for the prophylaxis of migraine headache in adults in the United States and many other countries. The practical issues discussed in this article will enable clinicians to maximize the effectiveness while minimizing the side effects associated with this preventive agent.
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PMID:Practical use of topiramate for migraine prevention. 1583 92


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