Anticonvulsants are close to the drugs drowsing on pharmacological properties, and partly and on chemical structure.
Various substances weakening progresses of excitement or strengthening processes of braking in central nervous system including barbiturates, bromides, tranquilizers of different groups, etc. can have anticonvulsant effect.
However a number of funds is allocated by the specific anticonvulsant activity and efficiency at the morbid conditions which are followed by convulsive reactions (in intoxications, infectious diseases, central nervous system injuries, etc.). The anticonvulsants effective in epilepsy and applied to prevention or stopping of spasms or the equivalents corresponding to them have special value (loss or disturbance of consciousness, behavioural and vegetative disorders, etc.) at certain forms of this disease.
Synthetic connections of different chemical groups belong to anticonvulsant (antiepileptic) means: derivatives of barbituric acid (phenobarbital, benzonal, benzobamit, a hexamidine); hydantoin derivatives (dipheninum), oksazolidindiona (Trimethinum), suktsinimida (Ethosuximidum, Puphemidium), iminostilbene derivatives (carbamazepine), etc. The benzodiazepine drugs rendering especially expressed anticonvulsant, action (clonazepam, etc.) are rather recently developed. There was essentially new group of antiepileptic means - valproic acid and its salts (atsediprol or Convulexum, etc.).
Depending on the chemical building and pharmacological properties various anticonvulsant (antiepileptic) drugs show primary activity at different forms of epilepsy. So, in big convulsive attacks (grand mal) apply first of all phenobarbital and dipheninum; also the hexamidine, carbamazepine, valproic acid are effective. At psychomotor equivalents use mainly carbamazepine, dipheninum, a hexamidine, clonazepam, and at small attacks (petit mal) - trimety, suktsinimida, benzodiazepines, valproic acid. Diazepam (Sibazonum) is entered intravenously at the epileptic status. Different anticonvulsant drugs use also at convulsive reactions of not epileptic nature.
As a rule, anticonvulsant drugs have no strict specificity in relation to different forms of epilepsy. The same drug can be in different degree effective at various manifestations of epilepsy. At the same time there is no drug of universal type of the action rather effective at all forms and manifestations of epilepsy, yet. Therefore quite often at the same time appoint different antiepileptic means in various combinations, and if necessary make replacement of one drug with another.
The mechanism of action antiepileptic is studied by drug insufficiently. Note a possibility of decrease under the influence of these drugs of excitability of neurons of the epileptic center. Recently it is paid to studying a role of neurotransmitters in pathogenesis of epilepsy much attention. Consider that the supersensitivity of neurons and instability of membrane potentials leading to spontaneous categories can be caused by increase in concentration of the central stimulating neurotransmitters or reduction of maintenance of the braking neurotransmitters. In this regard the question of a role of these mediators in the mechanism of action of antiepileptic means is studied. Special attention is paid at the same time at - the aminobuttered acid (GAMK) which is the main brake mediator in central nervous system. Also the role of other brake amino-acid mediator - glycine and exciting amino-acid mediators - a glutamate and aspartate is studied.
One of modern antiepileptic drugs which effect is considerably connected with increase in concentration of GAMK is valproic acid (see Atsediprol).
Diacarbum (see) which is karboangidraza enzyme inhibitor possesses the special mechanism of action (see. Diuretic means). It is applied mainly at small forms of epilepsy (with rare absentias epileptica).
There are instructions on anticonvulsant effect of Allopyrinolum (see).
Antiepileptic drugs are used usually continuously and it is long therefore it is necessary to watch carefully their shipping, to consider their characteristic toxic properties, to be careful in dosing, considering pharmacokinetic parameters.
Main types of side effect of these drugs are allergic, toxic and metabolic reactions. The allergic reactions which are expressed not only in the form of skin and other usual manifestations, but also in the form of increase of attacks, deterioration in a mental state, etc., demand immediate cancellation of the used drug and replacement with its drug of other group. Toxic reactions (psychopathological and neurologic syndromes, a leukopenia and other hematologic disorders) are more often observed at long uncontrolled administration of drug. In such cases the gradual dose decline and the corresponding disintoxication therapy are necessary. Metabolic disturbances (endocrine disorders, megaloblastichesky anemia, etc.) demand immediate cancellation of the used drug and replacement with his another. Especially thorough observation is necessary at combined use of antiepileptic drugs, first of all at patients with the residual phenomena of the postponed organic diseases of a brain.
Replacement of one antiepileptic means with another should be made gradually, reducing a dose of earlier used drug and replacing it with new drug in the accruing doses. In order to avoid decoration of attacks it is necessary to watch that between the drugs reappointed and earlier applied the ratios of doses equivalent on action force remained. For different drugs these ratios are various. For example, equivalent ratios of doses of some drugs to the phenobarbital doses (taken for 1) make for dipheninum about 1, 4:1; for a hexamidine 3:1; for benzonal 2:1; for Chloraconum 15:1.
Cancellation of antiepileptic drugs in all cases has to be made gradually (in order to avoid development of attacks up to the epileptic status).
It is necessary to consider that antiepileptic drugs can get through a placental barrier and have teratogenic effect. In foreign literature cases of anomalies of development in newborns which mothers accepted sodium Valproatum and also carbamazepine in combination with sodium Valproatum, dipheninum or phenobarbital are described.
In some cases at use of antiepileptic drugs (phenobarbital, dipheninum, a hexamidine, Valproatums, etc.) the deficiency of folic acid develops that demands completion of this vitamin. At the same time high doses of folic acid can weaken anticonvulsant effect of these drugs and promote increase of epileptic seizures.
Cases of deficiency of vitamin K with bleedings at newborns whose mothers accepted phenobarbital, a hexamidine, dipheninum are noted. If necessary should appoint preventively the pregnant women accepting antiepileptic means, vitamin K drugs (under control of a coagulant system of blood).