Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00512 (Phenytoin)
 1,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein binding of phenytoin was assesed in one patient with dialysis encephalopathy before and after haemodialysis. Phenytoin concentrations were measured by radioimmunoassay and continuous ultrafiltration was used to assess phenytoin binding. At a serum concentration of 60 micromol.1-1 the percentage of phenytoin bound to serum albumin was considerably lower in the patient serum (79.95% predialysis; 92.09% postdialysis) than that in three normal sera (97.90 +/- 0.17%). Analysis of Scatchard plots indicated two classes of binding sites. In class I both the affinity and capacity for binding phenytoin were reduced in the pre and post-dialysis serum, whereas in class II the capacity of the uraemic serum was increased although the intrinsic association constant was greatly reduced. It was concluded that in vivo haemodialysis is associated with large fluctuations in the protein binding of phenytoin, in which the concentration of endogenous dialysible metabolites are strongly implicated.
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PMID:Alterations of phenytoin protein binding with in vivo haemodialysis in dialysis encephalopathy. 42 30

Similar movement disorders developed in two 8-year-old retarded children while they were receiving phenytoin. Seizures subsequent to a diphtheria-pertussis-tetanus immunization had developed in each child at 1 to 2 months of age. A static encephalopathy ensued, characterized by mental retardation, ataxia, spasticity, and a mixed seizure disorder. Intermittent dystonia and choreoathetosis developed insidiously while serum phenytoin concentrations were in the therapeutic range. Sustained dystonia and choreoatheosis developed 2 hours after an oral provocation with phenytoin. The baseline abnormalities on the electroencephalogram remained unchanged during the choreoathetosis. Recognizable metabolic abnormalities known to be associated with similar movement disorders were excluded. It was concluded from these studies that the movement disorder is secondary to phenytoin and can occur at therapeutic serum concentrations. Phenytoin is a central anticholinergic agent and a central stimulant of serotonin, and may induce movement disorders as a result of altering these neurotransmitters in the brain. The variable expression of these movement disorders may relate to the nature of the preexisting striatal insult.
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PMID:Phenytoin-induced dystonia and choreoathetosis in two retarded epileptic children. 94 1

In a review of more than 200 studies over the last three decades, the manifold psychic effects of anticonvulsives on healthy persons, on patients with and without epilepsy, on patients with mental disorders with or without cerebral damages are analysed and summarized. The following results are mainly shown: 1. Carbamazepine: a positive effect on "expansive" behaviour and mood can be observed in about 50-60% of the patients. The cognitive and psychomotor performance is almost unchanged. 2. Valproinate: Negative psychic effects can rarely be seen for a longer time (exception: reversible encephalopathy). The behaviour can similarly be influenced as with carbamazepine. 3. Phenytoin: Cognitive and psychomotor performance is negatively influenced. The effects on behaviour are contradictory. 4. Phenobarbitone and Primidone: Diverse negative effects on performance and behaviour, especially as "expansive" disorders in children and adolescents, seemed to be proven. 5. Ethosuximide: Beside the drug specific provocation of psychotic disorders, both, positive and negative effects on behaviour and cognitive functions are discussed. 6. The psychic effects of other anticonvulsives such as Benzodiazepines, Sulthiame and Pheneturide are shortly summarized. 7. Polytherapy: Negative influences on psychic functions are significant. Finally the results are discussed concerning their clinical relevance.
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PMID:[Anticonvulsants and their psychological effects--a review]. 240 25

17 (33%) of 52 patients who underwent 56 consecutive orthotopic liver transplants had serious neurological complications postoperatively. The commonest complication was fits, which occurred in 13 (25%) patients. 50% of patients had their onset of fits within the first week. In 3 patients the fits were associated with postoperative metabolic encephalopathy and fatal progressive neurological deterioration. In some patients the evidence implicating cyclosporin in the development of fits is strong. In others factors such as electrolyte disturbances, steroid treatment for graft rejection, and cerebral infarction may have contributed to the development of the fits. Phenytoin controlled the fits in 10 out of 13 patients. Other neurological complications included 1 case of central pontine myelinolysis, 1 of cerebral abscess, and 4 of non-encephalopathic psychosis.
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PMID:Neurological complications following liver transplantation. 288 42

A 81 year-old female, weighing 56 kgs, had taken carbamazepine (10.2 mg/kg/day) for simple partial motor seizures of recent onset during 15 days. EEG recording showed slow waves on the left hemisphere. CT was normal. The seizures were controlled for a few days and then reappeared beginning as simple partial seizures and progressing to impairment of consciousness. The patient became confused. On admission she was severely confused. Neurological examination was otherwise normal. Plasma sodium level was 134 meq/l and CBZ plasma level was 4.3 micrograms/ml. EEG showed high voltage bilateral delta waves and a left focus. The drug was withdrawn with relief of clinical symptoms and to a lesser extent, of EEG abnormalities. Phenytoin encephalopathy is a well known pathological entity but to our knowledge there has been no report of carbamazepine encephalopathy with neither excessive plasma level of the drug nor water intoxication. An idiosyncratic reaction is considered likely.
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PMID:[Subacute encephalopathy. Idiosyncratic reaction to carbamazepine?]. 361 67

A case of phenytoin-induced hepatitis with mononucleosis is reported, and syndromes associated with phenytoin hypersensitivity reactions are discussed. A 23-year-old black woman with a two-month history of seizure disorder was admitted to a hospital with nausea, vomiting, fever, lymphadenopathy, diffuse maculopapular rash, left-upper-quadrant tenderness, and hepatomegaly. She was receiving phenytoin sodium 300 mg/day; carbamazepine 200 mg four times daily had been discontinued four days before admission because of leukopenia. Phenytoin was discontinued after admission; however, phenytoin 1 g i.v. was given for a tonic-clonic seizure two days after admission, after which swelling of the face and legs and pruritus developed. Over the next few days, signs and symptoms of hepatotoxicity progressed, and she became comatose. Seizures were treated with diazepam. She began to recover after 10 days of supportive therapy and was discharged several weeks later on primidone therapy. Serious phenytoin hypersensitivity reactions may appear as dermatologic, lymphoid, or hepatic syndromes. Fever, rash, and lymphadenopathy often accompany hepatic injury. Encephalopathy and death may occur. Proposed mechanisms for phenytoin hypersensitivity include antigen-antibody reactions, alteration of lymphocyte function, and an enzyme abnormality causing the production of toxic metabolites. Treatment is supportive; phenobarbital and carbamazepine may be used with caution as alternate anticonvulsant therapy. The possibility of phenytoin hypersensitivity reactions should be considered when patients receiving phenytoin have unusual symptoms, particularly fever, rash, and lymphadenopathy.
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PMID:Phenytoin-induced hypersensitivity reactions. 367 71

We report a patient with a severe hypoxic encephalopathy. The electroencephalogram revealed both an "alpha-coma" pattern and generalized intermittent runs of 11/2-21/2 spikewave activity. The paroxysmal activity was suppressed by Dilantin leaving the underlying "alpha rhythm" intact. This association has only been touched upon in the past.
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PMID:"Alpha-coma" in association with generalization paroxysmal (spike-wave) activity: a case report. 723 51

Subacute encephalopathy developed in four patients within one to two months after undergoing high-dose chemotherapy and bone marrow transplantation or peripheral blood progenitor (stem) cell transplantation for breast cancer, acute myeloid leukemia, and non-Hodgkin's lymphoma. None of the patients had previously known neurologic disorders, central nervous tumor or infection. Two patients presented with generalized tonic, clonic seizures, and two with confusion and lethargy. In all patients lumbar puncture and CT scans of the brain were normal, while magnetic resonance imaging (MRI) demonstrated multifocal predominantly white matter lesions. Phenytoin therapy was given to the two patients with seizures and all four patients improved without specific therapeutic intervention. Repeat MRIs became normal within three months. We report a delayed and transient encephalopathy which appears to be a unique complication of high-dose cytotoxic chemotherapy. The corresponding brain lesions may not be appreciated on CT scans, suggesting an expanded role for MRI studies in patients who develop neurologic findings while undergoing high-dose cytotoxic therapy.
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PMID:Delayed, transient encephalopathy after marrow transplantation: case reports and MRI findings in four patients. 884 58

Seizures are commonly encountered in patients who do not have epilepsy. Factors that may provoke such seizures include organ failure, electrolyte imbalance, medication and medication withdrawal, and hypersensitive encephalopathy. There is usually one underlying cause, which may be reversible in some patients. A full assessment should be done to rule out primary neurological disease. Treatment of seizures in medically ill patients is aimed at correction of the underlying cause with appropriate short-term anticonvulsant medication. Phenytoin is ineffective in the management of seizures secondary to alcohol withdrawal, and in those due to theophylline or isoniazid toxicity. Control of blood pressure is important in patients with renal failure and seizures. Non-convulsive status epilepticus should be considered in any patient with confusion or coma of unclear cause, and electroencephalography should be done at the earliest opportunity. Most ill patients with secondary seizures do not have epilepsy, and this should be explained to patients and their families. Only those patients with recurrent seizures and uncorrectable predisposing factors need long-term treatment with anticonvulsant medication.
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PMID:Medical causes of seizures. 980 2

Phenytoin (5,5-diphenylhydantoin), which has been in use for 60 years, is still an important antiepileptic drug. Its primary mechanism of action is modulation of the sustained repetitive firing of neurones by direct inhibition and blockage of voltage-gated sodium channels in the neuronal cell membrane, and by delay of cellular reactivation. The plasma protein binding of phenytoin is normally between 90% and 95%. The drug is rapidly distributed from the blood to the tissues and is almost completely metabolized in the liver. The plasma phenytoin concentration normally reaches the steady-state level within 1-2 weeks. The half-life of phenytoin is less than 20 h in low doses, but is prolonged in high doses, newborn infants and elderly people. The half-life is shortened when phenytoin is given concomitantly with an enzyme-inducing drug, such as phenobarbital or carbamazepine. Phenytoin is effective for treating generalized tonic-clonic seizures, partial seizures with or without generalization, and convulsive status epilepticus. Over the years, many new, and even serious, adverse effects of phenytoin have been recognized. Phenytoin encephalopathy, manifesting as cognitive impairment and a cerebellar syndrome, is an important adverse neurological effect, the development of which depends on the saturation kinetics of phenytoin, individual differences in phenytoin metabolism, an inhibitory effect of certain drugs on phenytoin metabolism, or the ability of certain drugs to displace phenytoin from plasma proteins, leading to an increase in the plasma level of unbound phenytoin. Because of its potentially adverse effects, phenytoin is not recommended as the first choice for treating epileptic seizures, except as a co-drug for managing convulsive status epilepticus. In patients with epilepsy who also have intellectual disability, and are susceptible to balance disturbances and cognitive dysfunction, it is wise to replace phenytoin with another drug, such as carbamazepine or oxcarbazepine. The long-term use of phenytoin is not recommended for patients with loss of locomotion, marked cognitive impairment, or symptoms and signs of cerebellar disease. The prevention of phenytoin intoxication, with the subsequent development of phenytoin-induced encephalopathy, depends on careful observation of the patients and frequent monitoring of plasma levels of phenytoin and other concomitantly administered antiepileptic drugs.
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PMID:Phenytoin: effective but insidious therapy for epilepsy in people with intellectual disability. 1003 Apr 28


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