Anticonvulsant drug mechanisms. Phenytoin, phenobarbital, and ethosuximide and calcium flux in isolated presynaptic endings. 1976

R S Sohn, and J A Ferrendelli

Phenytoin, phenobarbital, ethosuximide, and procaine hydrochloride were evaluated for their ability to inhibit Ca2+ flux into isolated presynaptic endings (synaptosomes) prepared from rabbit neocortex. Calcium influx produced by depolarizing concentrations (69 mM) of K+ was inhibited 7% to 63% by phenytoin, phenobarbital, or procaine, whereas ethosuximide was ineffective. Decreased Ca2+ influx was observed with as little as 0.08 mM phenytoin and 0.04 mM phenobarbital. In contrast, 4 mM procaine was needed to produce an effect. These results lead to the conclusion that ability to produce membrane stabilization is not a property of all anticonvulsant drugs; however, this property may be essential for the action of drugs effective in the treatment of major seizures.

UI MeSH Term Description Entries
D010634 Phenobarbital A barbituric acid derivative that acts as a nonselective central nervous system depressant. It potentiates GAMMA-AMINOBUTYRIC ACID action on GABA-A RECEPTORS, and modulates chloride currents through receptor channels. It also inhibits glutamate induced depolarizations. Phenemal,Phenobarbitone,Phenylbarbital,Gardenal,Hysteps,Luminal,Phenobarbital Sodium,Phenobarbital, Monosodium Salt,Phenylethylbarbituric Acid,Acid, Phenylethylbarbituric,Monosodium Salt Phenobarbital,Sodium, Phenobarbital
D010672 Phenytoin An anticonvulsant that is used to treat a wide variety of seizures. It is also an anti-arrhythmic and a muscle relaxant. The mechanism of therapeutic action is not clear, although several cellular actions have been described including effects on ion channels, active transport, and general membrane stabilization. The mechanism of its muscle relaxant effect appears to involve a reduction in the sensitivity of muscle spindles to stretch. Phenytoin has been proposed for several other therapeutic uses, but its use has been limited by its many adverse effects and interactions with other drugs. Diphenylhydantoin,Fenitoin,Phenhydan,5,5-Diphenylhydantoin,5,5-diphenylimidazolidine-2,4-dione,Antisacer,Difenin,Dihydan,Dilantin,Epamin,Epanutin,Hydantol,Phenytoin Sodium,Sodium Diphenylhydantoinate,Diphenylhydantoinate, Sodium
D011343 Procaine A local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1016). Anuject,Geriocaine,Gerokit,Hewedolor-Procain,Lophakomp-Procain N,Novocain,Novocaine,Procain Braun,Procain Jenapharm,Procain Rödler,Procain Steigerwald,Procain curasan,Procaina Serra,Procaine Hydrochloride,Pröcaine chlorhydrate Lavoisier,Röwo Procain,procain-loges,Hydrochloride, Procaine
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D002118 Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005013 Ethosuximide An anticonvulsant especially useful in the treatment of absence seizures unaccompanied by other types of seizures. Ethosuccimid,Emeside,Ethylmethylsuccimide,Ethymal,Etosuximida Faes,Petnidan,Pyknolepsinum,Suksilep,Suxilep,Zarontin,Faes, Etosuximida
D005260 Female Females
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013574 Synaptosomes Pinched-off nerve endings and their contents of vesicles and cytoplasm together with the attached subsynaptic area of the membrane of the post-synaptic cell. They are largely artificial structures produced by fractionation after selective centrifugation of nervous tissue homogenates. Synaptosome

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