Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Valproic acid is a new antiepileptic drug. It has a marked effect on generalized spike-wave discharges. The exact mechanism of action is uncertain; however, some evidence suggests an effect on the metabolism of gamma-aminobutyric acid. It is rapidly absorbed from the gastrointestinal (GI) tract. Concurrent administration with phenobarbital may result in elevated phenobarbital plasma concentrations. Administration with phenytoin sodium may transiently result in lower total phenytoin plasma levels. Side effects are generally mild and include fatigue, GI disturbances, weight gain, a fine postural and resting tremor, mild thrombocytopenia, and an increase in hepatic enzymes. Platelet counts and liver function monitoring should be done during valproic acid therapy. Drowsiness may be seen in patients receiving other antiepileptic drugs concurrently.
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PMID:Valproic acid. Review of a new antiepileptic drug. 11 Feb 94

2-Propyl-1-aminopentane (2-PAPN), a branched aliphatic amine, was found to be readily deaminated by monoamine oxidase B in the liver of the rat and semicarbazide-sensitive amine oxidase in the aorta of the rat. The deaminated product, 2-propyl-1-pentaldehyde, could be subsequently converted to valproic acid in the presence of aldehyde dehydrogenase and beta-NAD cofactor in vitro as well as in vivo. Valproic acid was identified after derivatization with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC-fluorometric assessment. Absorption and biotransformation of a single intraperitoneal dose of 2-PAPN resulted in the rapid appearance of the drug and its metabolite in the blood and in the brain. The formation of valproic acid from 2-PAPN in vivo, however, was insufficient to facilitate anticonvulsant action. In fact, 2-PAPN itself, at relatively small doses, exhibited distinct tremor effects. Such tremor effects could be prevented by valproic acid. However, 2-PAPN was also found to potentiate the convulsant effect induced by mercaptopropionic acid (MPA) and, in addition, the 2-PAPN-induced tremor could be potentiated by MPA in mice.
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PMID:2-propyl-1-aminopentane, its deamination by monoamine oxidase and semicarbazide-sensitive amine oxidase, conversion to valproic acid and behavioral effects. 186 97

Valproic acid is a branched-chained fatty acid, structurally unrelated to any other antiepileptic drug. Since publication of the original review in the Journal in 1977, several clinical trials have documented its efficacy and safety in adults and children for the treatment of generalised seizures (absence, tonic-clonic, myoclonic), partial seizures (simple, complex, secondarily generalised) and compound/combination seizures (including those refractory to treatment with other antiepileptic drugs). Valproic acid monotherapy has demonstrated efficacy equivalent to that of carbamazepine, phenytoin, and phenobarbital in the treatment of both generalised and partial seizures and ethosuximide in the treatment of absence seizures. Adverse effects associated with the drug are primarily gastrointestinal (nausea, vomiting, dyspepsia) in nature, although the use of enteric-coated formulations has reduced the incidence of abdominal discomfort. Weight gain, tremor and transient hair loss are commonly reported. Importantly, valproic acid has minimal neurological adverse effects (sedation, ataxia, impairment of cognitive function) compared with other antiepileptic drugs, a finding that may be of particular relevance in many patients with epilepsy. The incidence of rare, fatal liver failure has been greatly reduced by identifying and avoiding administration of valproic acid to high risk patient populations. An estimated risk of 1 to 2% for neural tube defects, predominantly spina bifida aperta, with maternal use of valproic acid therapy has been reported. Valproic acid inhibits hepatic drug metabolism and displaces other highly bound drugs from their plasma protein binding sites. Therefore, coadministered drugs which are highly protein bound or hepatically metabolised may require dosage adjustment. Enzyme-inducing antiepileptic drugs may increase valproic acid metabolism and necessitate increasing its dosage. Thus, comparative trials and extensive clinical experience have demonstrated the efficacy and tolerability of valproic acid and support its role as a valuable and well established first-line treatment for patients with a broad range of seizure types.
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PMID:Valproic acid. A reappraisal of its pharmacological properties and clinical efficacy in epilepsy. 751 5

Phenobarbital (phenobarbitone) and phenytoin are the most useful anticonvulsants in neonates because adverse effects are most readily reversed when these drugs are used. Most anticonvulsants are very rarely associated with haematological adverse effects. Platelet function is particularly vulnerable to valproic acid (sodium valproate) therapy. Barbiturates and phenytoin can precipitate metabolic bone disease. Although very infrequent, lymphadenopathy is most common with phenytoin, and lupus-like illnesses with ethosuximide. Valproic acid may precipitate underlying metabolic disorders. Nephrolithiasis can occur with topiramate. Liver disease is most likely with felbamate or valproic acid, but can occur with other anticonvulsants. Valproic acid and ethosuximide are the main precipitants of gastrointestinal symptomatology; while valproic acid and vigabatrin are frequently associated with excessive bodyweight gain. Rash is most likely to occur with barbiturates, but there is a high risk of this adverse effect if large doses of lamotrigine are given with valproic acid. Adverse cosmetic effects are most likely with phenytoin, but valproic acid may cause alopecia. All anticonvulsants may cause unwanted neurological effects: when they occur, diplopia is usually precipitated by carbamazepine; tremor by valproic acid; and other motor disturbances are probably most common with phenytoin. Most anticonvulsants can cause drowsiness. Phenobarbital leads anticonvulsants as a cause of behavioural difficulties. Effects of anticonvulsants on cognitive function are difficult to assess, but subtle changes have been reported for all anticonvulsants in use up to the 1980s. Compared with other anticonvulsant drugs, phenytoin and felbamate are more often discontinued as a result of unwanted effects.
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PMID:A comparative review of the adverse effects of anticonvulsants in children with epilepsy. 896 93

Thirty-five years since its introduction into clinical use, valproate (valproic acid) has become the most widely prescribed antiepileptic drug (AED) worldwide. Its pharmacological effects involve a variety of mechanisms, including increased gamma-aminobutyric acid (GABA)-ergic transmission, reduced release and/or effects of excitatory amino acids, blockade of voltage-gated sodium channels and modulation of dopaminergic and serotoninergic transmission. Valproate is available in different dosage forms for parenteral and oral use. All available oral formulations are almost completely bioavailable, but they differ in dissolution characteristics and absorption rates. In particular, sustained-release formulations are available that minimise fluctuations in serum drug concentrations during a dosing interval and can therefore be given once or twice daily. Valproic acid is about 90% bound to plasma proteins, and the degree of binding decreases with increasing drug concentration within the clinically occurring range. Valproic acid is extensively metabolised by microsomal glucuronide conjugation, mitochondrial beta-oxidation and cytochrome P450-dependent omega-, (omega-1)- and (omega-2)-oxidation. The elimination half-life is in the order of 9 to 18 hours, but shorter values (5 to 12 hours) are observed in patients comedicated with enzyme-inducing agents such as phenytoin, carbamazepine and barbiturates. Valproate itself is devoid of enzyme-inducing properties, but it has the potential of inhibiting drug metabolism and can increase by this mechanism the plasma concentrations of certain coadministered drugs, including phenobarbital (phenobarbitone), lamotrigine and zidovudine. Valproate is a broad spectrum AED, being effective against all seizure types. In patients with newly diagnosed partial seizures (with or without secondary generalisation) and/or primarily generalised tonic-clonic seizures, the efficacy of valproate is comparable to that of phenytoin, carbamazepine and phenobarbital, although in most comparative trials the tolerability of phenobarbital was inferior to that of the other drugs. Valproate is generally regarded as a first-choice agent for most forms of idiopathic and symptomatic generalised epilepsies. Many of these syndromes are associated with multiple seizure types, including tonic-clonic, myoclonic and absence seizures, and prescription of a broad-spectrum drug such as valproate has clear advantages in this situation. A number of reports have also suggested that intravenous valproate could be of value in the treatment of convulsive and nonconvulsive status epilepticus, but further studies are required to establish in more detail the role of the drug in this indication. The most commonly reported adverse effects of valproate include gastrointestinal disturbances, tremor and bodyweight gain. Other notable adverse effects include encephalopathy symptoms (at times associated with hyperammonaemia), platelet disorders, pancreatitis, liver toxicity (with an overall incidence of 1 in 20,000, but a frequency as high as 1 in 600 or 1 in 800 in high-risk groups such as infants below 2 years of age receiving anticonvulsant polytherapy) and teratogenicity, including a 1 to 3% risk of neural tube defects. Some studies have also suggested that menstrual disorders and certain clinical, ultrasound or endocrine manifestations of reproductive system disorders, including polycystic ovary syndrome, may be more common in women treated with valproate than in those treated with other AEDs. However, the precise relevance of the latter findings remains to be evaluated in large, prospective, randomised studies.
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PMID:Pharmacological and therapeutic properties of valproate: a summary after 35 years of clinical experience. 1226 62

Antiepileptic drugs (AEDs) are increasingly used for the treatment of several non-epileptic neurological conditions and psychiatric disorders. Most of the information available on the use of these agents in clinical disorders outside epilepsy is from case series, uncontrolled studies or small randomised clinical trials, and their apparent efficacy requires confirmation through well designed, large, phase III trials. With regard to neurological conditions other than epilepsy, experimental evidence for the efficacy of AEDs is only available for the treatment of patients with trigeminal neuralgia, neuropathic pain syndromes, migraine and essential tremor. Carbamazepine is commonly prescribed as first-line therapy for patients with trigeminal neuralgia. Gabapentin has been recently marketed for the management of neuropathic pain syndromes, particularly diabetic neuropathy and postherpetic neuralgia. Valproic acid (sodium valproate), in the form of divalproex sodium, is approved for migraine prophylaxis. Primidone can be considered a valuable option for the treatment of essential tremor. AEDs are also used to treat psychiatric conditions, in particular bipolar disorder. So far, the most commonly utilized AEDs in the treatment of this disorder have been carbamazepine and valproic acid, which have showed an antimanic efficacy and a probable long-term, mood-stabilizing effect in many bipolar patients, including those refractory or intolerant to lithium. The availability of a new generation of AEDs has broadened the therapeutic options in bipolar disorder. Lamotrigine, oxcarbazepine, gabapentin and topiramate appear to be promising in the treatment of refractory bipolar disorder, as a monotherapy as well as in combination with traditional mood stabilizers. In addition, newer AEDs appear to have a more favourable tolerability and drug interaction profile as compared to older compounds, so thus improving compliance to treatment.
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PMID:Antiepileptic drugs: indications other than epilepsy. 1524 50

Valproic acid-associated hyperammonemic encephalopathy (VHE) has been described in the neurology and emergency medicine literature, but the case reports identified therein are rarely derived from the psychiatric use of this medication. Valproic acid is widely used as a mood stabilizer in bipolar affective disorder and schizoaffective disorder. Patients with normal blood levels, liver function and metabolic tests may present with markedly elevated ammonia and a variety of neurological symptoms. We report the case of a patient on long-term valproic acid therapy, with stable dosing, who presented with an elevated ammonia level, new-onset tremor, confusion, and loss of consciousness. This case illustrates the need to check ammonia levels in psychiatric patients who are taking valproic acid and who present with new neurological symptoms.
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PMID:Valproic acid-associated hyperammonemic encephalopathy: a case report from the psychiatric setting. 1560 19

Valproic acid (VPA) is an antiepileptic drug widely used and well-tolerated by most of patients. Its non-dose-dependent side effects seen mostly are the temporary gastrointestinal disturbances including anorexia and nausea, and hepatoxicity. As to its dose-dependent side effects are the weight loss, tremor, skin eruption and the alopecia. In this study we aimed to put forward the biotinidase deficiency considered as a possible cause of alopecia in the rats administered with valproic acid, and the correlation between liver and serum biotinidase enzyme activities (BEA) and transaminases, albumin and serum valproic acid levels. In our study, 4 groups of which one of them was a control group, each consisting of 15 male Wistar rats was organized. 200, 400, and 600 mg/kg/day of VPA, and distilled water, two divided doses per day, were administered per orally to VPA-1, VPA-2, VPA-3, and control group, respectively, in 60 days. Their serum and liver biotinidase enzyme activities, serum AST, ALT, albumin, and valproic acid levels were measured. Alopecia was seen in the subjects of 6.6% of VPA-1, 13.3% of VPA-2, and 26.6% of VPA-3. Significant difference in the liver tissues BEA was noted only between VPA-3 and the control group. Reductions were observed both in the liver tissues BEA and the serum BEA levels, which are inversely proportional to the VPA doses. A positive correlation between the liver biotinidase enzyme activities and the serum valproic acid levels, and the negative correlation between the liver tissues biotinidase activities and the serum valproic acid levels were noted, respectively. As a conclusion, the partial alopecia which is an initial symptom of reduced biotinidase activity may also be created depending on the reduction of biotinidase activity during valproic acid therapy. The alopecia which may further be observed in the patients receiving valproic acid therapy may be prevented by means of administration of biotin in a dose of 10 mg/day.
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PMID:Serum and liver tissue biotinidase enzyme activity in rats which were administrated to valproic acid. 1668 56

Unverricht-Lundborg disease (ULD), progressive myoclonic epilepsy type 1 (EPM1, OMIM254800), is an autosomal recessively inherited neurodegenerative disorder characterized by age of onset from 6 to 16 years, stimulus-sensitive myoclonus, and tonic-clonic epileptic seizures. Some years after the onset ataxia, incoordination, intentional tremor, and dysarthria develop. Individuals with EPM1 are mentally alert but show emotional lability, depression, and mild decline in intellectual performance over time. The diagnosis of EPM1 can be confirmed by identifying disease-causing mutations in a cysteine protease inhibitor cystatin B (CSTB) gene. Symptomatic pharmacologic and rehabilitative management, including psychosocial support, are the mainstay of EPM1 patients' care. Valproic acid, the first drug of choice, diminishes myoclonus and the frequency of generalized seizures. Clonazepam and high-dose piracetam are used to treat myoclonus, whereas levetiracetam seems to be effective for both myoclonus and generalized seizures. There are a number of agents that aggravate clinical course of EPM1 such as phenytoin aggravating the associated neurologic symptoms or even accelerating cerebellar degeneration. Sodium channel blockers (carbamazepine, oxcarbazepine) and GABAergic drugs (tiagabine, vigabatrin) as well as gabapentin and pregabalin may aggravate myoclonus and myoclonic seizures. EPM1 patients need lifelong clinical follow-up, including evaluation of the drug-treatment and comprehensive rehabilitation.
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PMID:Clinical picture of EPM1-Unverricht-Lundborg disease. 1832 13

Valproic acid (VPA) is approved by the Food and Drug Administration (FDA) for the treatment of manic or mixed episodes associated with bipolar disorder. VPA is also used off-label to treat other conditions in psychiatry such as impulse control disorders, major depression, and posttraumatic stress disorder (PTSD). Although VPA is mostly well-tolerated, common adverse effects include gastrointestinal symptoms (nausea, vomiting, diarrhea), neurological symptoms (sedation, ataxia, tremor), weight gain, and alopecia. Less common adverse effects include VPA-induced parkinsonism and cognitive impairment. We describe a patient who developed parkinsonism and cognitive impairment eight years after starting divalproex sodium for bipolar disorder, type I. Over time, the patient's parkinsonian symptoms progressed, and the motor symptoms were partially responsive to carbidopa/levodopa. Her mild cognitive impairment was, for the most part, stable on donepezil. Rapid discontinuation of divalproex sodium resolved the parkinsonian symptoms as well as the cognitive impairment. A brief review of the literature regarding VPA-induced parkinsonism and cognitive impairment in adults is included. Given the reversible nature and potential severity of VPA-induced parkinsonism, improved recognition in psychiatric populations is critical, particularly after extended VPA exposure. To the best of our knowledge there are no reports describing the onset of VPA-induced parkinsonism in psychiatric patients more than eight years after starting VPA.
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PMID:Reversible Valproic Acid-Induced Parkinsonism and Cognitive Impairment in an Elderly Patient With Bipolar Disorder I. 2771 42


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