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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monkeys were treated intravenously with various anticonvulsant drugs before and after the intravenous administration of gamma hydroxybutyrate (GHB). Continuous electroencephalographic (EEG) and temperature monitoring was performed throughout all experiments. The GHB-induced EEG changes were abolished by ethosuximide and clonazepam, marginally improved by diazepam, and unaffected by phenobarbital. The GHB-induced myoclonic jerks were abolished by ethosuximide, significantly improved by diazepam, and worsened by clonazepam. Phenobarbital was effective in diminishing the frequency of GHB-induced myoclonic jerks only when given prior to administration of GHB. The GHB-induced stupor was improved only by ethosuximide. The GHB model of petit mal seizures is quite specific for drugs used in this disorder. GHB may play a role in the pathogenesis of absence seizures in children.
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PMID:Gamma hydroxybutyrate in the monkey. III. Effect of intravenous anticonvulsant drugs. 10 97

The aim of the study was to compare the effect of phenobarbital given to pregnant rabbits and of epileptic seizures on the course of pregnancy, the physical state, and central nervous system development of newborns. Phenobarbital was given orally during whole pregnancy or for the last ten days in amounts 18,5 mg/kg/body weight = 0,1 DL 50. Seizures of "grand mal" type were evoked with electrostimulator every day since the tenth day of pregnancy. Phenobarbital penetrates via placenta, reaches the organs of all fetuses, and seizures provoke hypoxaemia of fetuses. Phenobarbital administered during whole pregnancy exerts an teratogenous effect. Both injurious factors applied after teratogenous period cause a retardation of general development of fetuses. After phenobarbital administration slight brain lesions are visible in the light, electron microscopical and histochemical examination. More evident was the retardation of the development of the central nervous system after both of the examined injurious factors. In the brain stem and in the cortex the neurons are less mature and the synaptic junctions in the cortex are less numerous. In our experimental models phenobarbital seems to evoke more noxious effect than seizures in mothers.
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PMID:[Comparison of the transplacental effect of luminal and epileptic seizures in pregnant rabbits on the development of the fetal nervous system]. 12 44

Anticonvulsant therapy of seizure disorders in man is associated with the development of complications involving bone and mineral metabolism including hypocalcemia, elevated serum immunoreactive parathyroid hormone levels, and increased amounts of unmineralized bone or osteoid. The latter has been attributed to a reduction in serum-25-hydroxycholecalciferol levels resulting from increased hepatic metabolism of vitamin D. Using an in vitro recycling hepatic perfusion system, we have demonstrated that 5 d of phenobarbital treatment increases the hepatic production of [(3)H]25-hydroxyvitamin D(3) (4.3+/-0.3 vs. 3.3+/-0.2%/h, P <0.025) without affecting the biliary excretion of radioactivity. Furthermore, rachitic livers perfused with blood obtained from animals treated with phenobarbital for 5 d also manifested an increase in [(3)H]25-hydroxyvitamin D(3) production (4.6+/-0.5 vs. 3.3+/-0.2%/h, P < 0.02). Addition of phenobarbital or its major metabolite, p-hydroxyphenobarbital, directly to the perfusion apparatus had no effect on [(3)H]25-hydroxyvitamin D(3) production. Phenobarbital treatment was also attended by a decrease in the intrahepatic content of [(3)H]vitamin D(3) (11.7+/-0.4 vs. 17.5+/-0.7 dpm/mg liver protein, P < 0.001) without alterations in the content of [(3)H]25-hydroxyvitamin D(3). The data collectively suggest that the increased hepatic conversion of [(3)H]vitamin D(3) to [(3)H]25-hydroxyvitamin D(3) attending phenobarbital treatment is secondary to stimulation of the hepatic 25-hydroxylation system(s) by a metabolite of phenobarbital other than p-hydroxyphenobarbital and/or by metabolic alterations resulting from phenobarbital therapy.
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PMID:Phenobarbital-induced alterations in the metabolism of [3H]vitamin D3 by the perfused rachitic rat liver in vitro. 22 52

Electrical stimulation of the visual cortex evoked the cortical focal seizure restricted in the neighbor cortex of the stimulated area in gallamine-immobilized cats. The present experiment was performed to clarify the participation of anticonvulsants in the cortex itself. Phenytoin and carbamazepine depressed the focal seizure, as indicated by the shortening of seizure duration and the suppression of spreading. In addition, the high-frequency components in seizure disappeared with the use of these drugs. Phenobarbital and diazepam also shortened the seizure duration. However, the high-frequency components did not disappear although seizure amplitude was depressed. Trimethadione, acetazolamide, and dipropylacetate facilitated the focal seizure. From these results, the participation of the drugs affecting grand mal and partial epilepsies in the cortex is suggested. In addition, this experimental model is though to be useful in elucidating possible modes or mechanisms of anticonvulsant action on cortical neurons by analyzing, after drug administration, the changes in seizure patterns which seem to reflect underlying neuronal changes.
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PMID:Effect of anticonvulsants on cortical focal seizure in cats. 40 40

14C-phenytoin or 3H-phenobarbital were given through indwelling jugular catheters to 65 rats. Anticonvulsant activity was tested by the maximal electroshock seizure test and was correlated with brain concentrations of phenytoin or phenobarbital. Free and total plasma drug levels were determined by equilibrium dialysis. The median effective cerebral phenytoin concentration (EC50) was 10.5 microM/kg (95% fiducial limits, 8.2 to 12.4) 3 min after infusion compared with 10.2 microM/kg 30 min after infusion. The EC50 of phenobarbital was 8.2 microM/kg (6.7 to 9.3 microM/kg) 3 min after infusion. Cerebellar concentrations were equivalent to cerebral concentrations for all rats (r = 0.98). Three minutes after infusion, cerebral:plasma free ratio of phenytoin was 3.73 +/- 0.71 (+/- S.D.); the plasma protein bound:free ratio, 3.70 +/- 0.98. For phenobarbital, the cerebral:plasma free ratio was 0.72 +/- 0.10; the plasma protein bound:free ratio, 0.63 +/- 0.12. Since the EC50 values of phenytoin 3 or 30 min after infusion did not differ, onset of anticonvulsant effect clearly occurred as soon as adequate brain concentrations were attained. Phenobarbital was effective 3 min after infusion, and although much higher free plasma levels were necessary, effective brain concentrations were similar to those of phenytoin. Brain content paralleled plasma protein binding, both being high for phenytoin and low for phenobarbital.
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PMID:Intravenous phenytoin and phenobarbital: anticonvulsant action, brain content, and plasma binding in rat. 44 31

Interictal spikes with a configuration similar to that occurring in grand mal epilepsy were generated by the application of penicillin to a hippocampal slice preparation. This slice preparation has potential value for screening anticonvulsant drugs and for studying epileptic activity. The effect of anticonvulsant drugs on seizure activity was tested at concentrations comparable to reported clinical serum concentrations. Phenytoin and diazepam were maximally effective at concentrations of 20 microgram/ml and 3-4 microgram/ml, respectively, in good agreement with their effective concentrations in clinical practice. Phenobarbital was more potent (5 microgram/ml) and mesuximide (50% potent at 80 microgram/ml) was least effective.
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PMID:The hippocampal slice: a system for studying the pharmacology of seizures and for screening anticonvulsant drugs. 57 41

In a time-distribution study, the anticonvulsant effects of four benzodiazepine compounds were compared with those of three standard antiepileptics against metrazol-induced seizures in mice and rats. Ethosuximide and trimethadione had the shortest duration of action in mice, but protected the rats up to 6 hr. Phenobarbitone, diazepam, flurazepam and nitrazepam protected the mice up to 12 hr, but the rats were effectively protected only up to 3-4 hr. Clonazepam, the most potent and effective agent, protected the mice from clonic-tonic seizures up to 18-20 hr and the rats up to 6-7 hr. Comparison of the PD50 from clonic seizure at the peak-effect hours revealed that the benzodiazepines were 16 to 96 times more potent than phenobarbitone on a molar basis, while phenobarbitone itself was 12 to 26 times more potent than ethosuximide and trimethadione. Tonic seizures and mortality were largely suppressed by all drugs until 18-20 hr in mice and 6-7 hr in rats. Seizure latency and mortality patterns varied from drug to drug but not in a dose-dependent manner.
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PMID:The temporal dimensions of anticonvulsant action of some newer benzodiazepines against metrazol induced seizures in mice and rats. 59 70

The kindling of amygldaloid and cortical seizures in cats was used to study the prophylactic effects of phenobarbital, phenytoin, ethosuximide, acetazolamide, and dexamethason. Phenobarbital prevented the evolution of such seizures beyond stage 4 in all amygdaloid-kindling animals during 160 days of study. The prophylactic effect persisted on periodic challenge after the drug had been discontinued. Phenytoin, ethosuximide, acetazolamide, and dexamethasone appeared to have no prophylactic effect against the development of kindled amygdaloid seizures. With cortical kindling, both phenobarbital and phenytoin retarded the evolution of seizures without achieving true prophylaxis. The drugs appeared to act as suppressants. Prophylaxis was not an "all-or-none" phenomenon but rather a limitation of the stage of seizure evolution.
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PMID:Pharmacological prophylaxis against the development of kindled amygdaloid seizures. 61 67

Phenobarbital pharmacokinetics after intravenous injection were studied in 8 neonates with seizures. Subjects ranged in gestational age from 30 to 40 wk. Plasma concentrations of phenobarbital were measured by enzyme-multiplied immunoassay (EMIT). The volume of distribution (Vd) of phenobarbital was 0.97 +/- .15 L/kg which was independent of the dose administered. Vd and gestational age did not correlate. Phenobarbital clearance calculated from average concentrations in patients maintained on phenobarbital for 1 to 4 wks was consistent, with a decrease in t1/2 from 115 hr after 1 wk to 67 hr after 4 wk of therapy. The elimination of phenobarbital decreased at an exponential rate with a t1/2 of 4.6 days. A pharmacokinetic model with an exponentially increasing elimination rate term was used to describe the data. Average concentrations predicted with the use of the model corresponded adequately with experimental results. The increases in clearance observed are thought to be related to rates of turnover of drug-metabolizing enzymes in the neonate.
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PMID:Phenobarbital pharmacokinetics in neonates. 62 41

Effects of antiepileptics on both behavioral (TE) and electrographic seizure patterns induced by maximal electroshock were studied simultaneously in the same animal. The results obtained are as follows. All the antiepileptics used in this study depressed the TE seizure. Imipramine, biperiden, and lidocaine also depressed TE seizure, although they are not classified as antiepileptics. Phenobarbital, primidone, trimethadione, carbamazepine, ethosuximide, diazepam, clozapine, and imipramine had a depressant effect on electrographic seizures. However, phenytoin, ethotoin, phenacemide, and acetazolamide did not influence the electrographic seizure, in spite of having a strong effect on TE seizure. The present procedure, i.e., that of simultaneous observation of both behavioral and electrographic seizure patterns induced by maximal electroshock in the same animal, provides information which cannot be obtained from either behavior or EEG observation alone.
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PMID:Effects of antiepileptics on both behavioral and electrographic seizure patterns induced by maximal electroshock in rats. 73 31


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