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R L Rapport

Publications and source records attributed to R L Rapport.

7 recordsLinked to original sources
PubMed1979

Single-dose pharmacokinetics and anticonvulsant efficacy of primidone in mice.

The pharmacokinetics and efficacy of the anticonvulsant primidone (PRM) and its active metabolites, phenobarbital (PB) and phenylethylmalonamide (PEMA), were studied after single-dose administration in mice. The half-life of PB is twice that of PRM and PEMA. The plasma/brain ratios provide evidence of poor penetration of PRM into brain. The results support our findings of negligible or absent PRM concentrations in the brains of patients on primidone therapy who were undergoing surgery for intractable epilepsy. The anticonvulsant properties of PRM, PB, and PEMA against maximal electroshock in mice were also studied with the use of the metabolic inhibitor SKF 525A. The half-life, potency, peak anticonvulsant effect, and effective dose curves of these compounds indicate that the anticonvulsant effect of short-term oral PRM administration in mice is from derived PB.

Animals↗
PubMed1977

Phenytoin-related cerebellar degeneration without seizures.

Cerebellar changes have been reported in relationship to epilepsy alone as well as to phenytoin therapy for the control of seizures. The cliniconeuropathological correlation between these changes and epilepsy or the anticonvulsant is usually complicated by the presence of both variables. Experimental evidence suggests that phenytoin alone may be sufficient to cause cerebellar changes following intoxication. We report a case of cerebellar degeneration in a patient treated with isoniazid and prophylactically treated wtih phenytoin who never had a seizure.

Cerebellum↗
PubMed1977

Distribution characteristics of ethosuximide in discrete areas of rat brain.

The distribution properties of ethosuximide in four regions of the rat brain--cortex, midbrain, cerebellum, and pons-medulla--were investigated following chronic intraperitoneal administration of the drug (every 12 hr for 108 hr) at four dose levels (20, 40, 60, and 80 mg/kg). A gas-liquid chromatographic procedure was developed to quantitate ethosuximide levels in these tissues and plasma. The mean tissue/plasma ratios were 0.917, 0.942, 0.902, and 0.903 for cortex, midbrain, cerebellum, and pons-medulla, respectively. The distribution ratio for midbrain was significantly greater than that observed for cerebellum. For each brain region, the distribution ratio was independent of dose (20 to 80 mg/kg) and plasma concentration (8 to 135 microgram/ml).

Animals↗
PubMed1977

Surgical management of epilepsy.

Therapy with anticonvulsant drugs reduces the frequency and severity of seizures in many but not all epileptic patients. Unfortunately, in a significant number control remains poor even when maximal doses of multiple anticonvulsant drugs are given. Some of these patients are candidates for surgical treatment of epilepsy. The operative management of convulsive disorders is a well-established technique and is available in some centers. In selected cases, such operations are both safe and effective, with good longterm improvement or complete control in 76 percent of patients. We have summarized the 24-year experience with surgical operation for epilepsy at the University of Washington Medical Center.

Adolescent↗
PubMed1975

Prophylactically administered phenytoin. Effects on the development of chronic cobalt-induced epilepsy in the cat.

In chronic cobalt-induced experimental epilepsy in the cat, there are alterations in behavior, electroencephalograms, and brain sodium, potassium adenosine triphosphatase (Na,K ATPase) activity. The electrographic and enzymatic changes occur both in focus and homotopic cortex, and are time related. The onset of EEG paroxysms consistently precedes increases in Na,K ATPase activity, indicating that the enzymatic change is adaptive. Prophylactic treatment with phenytoin (formerly diphenylhydantoin) prevents these chronic alterations from developing, although some early changes do occur. After the drug is withdrawn following 28 days of therapy, treated animals still demonstrate no evidence of epileptiform discharges or changes in Na,K ATPase activity, although these changes persist in untreated cats. Given properly, phenytoin may prevent alterations in brain, which can result in the formation of a hyperexcitable population of cells. These data support the efficacy of early pharmacologic prophylaxis in posttraumatic epilepsy.

Adenosine Triphosphatases↗
PubMed1975

Human epileptic brain Na, K ATPase activity and phenytoin concentrations.

An abnormal flux of monovalent cations may be related to the epileptogenic process in man. One possible mechanism for deranged electrolyte metabolism in epileptic brain is an abnormality in sodium, potassium-dependent adenosine triphosphatase (Na, K ATPase). We found the activity of Na, K ATPase to be significantly less in epileptic human corfex than in nonepileptic cortex. Histological changes have been simultaneously evaluated in epileptic brain. A second membrane-bound enzyme, acetylcholinesterase (AChE), was also assayed as a marker for neuronal membranes and found not to correlate with the epileptogenicity of human brain. In addition, the concentrations of the anticonvulsant compound phenytoin have been determined in the serum and cerebral cortex of epileptic and nonepileptic patients. The ratio of phenytoin in cortex to serum concentration is significantly lower in epileptic patients than in nonepileptic controls.

Acetylcholinesterase↗