anticonvulsants

For drugs that have sedative effects, similar in pharmacological properties, and partly on the chemical structure of anticonvulsants.
Anticonvulsant action can have a variety of substances that weaken or strengthen advances excitation braking processes in the CNS, including barbiturates, bromides, tranquilizers and other various groups.
However, a number of funds allocated its specific anticonvulsant activity and efficacy in pathological conditions involving convulsive reactions (with intoxication, infectious diseases, central nervous system injuries, and others.). Special importance anticonvulsants, effective in epilepsy and used for the prevention or relief of cramps or corresponding equivalents (loss or impairment of consciousness, behavioral and autonomic dysfunction, and others.) In certain forms of the disease.
For anticonvulsant (antiepileptic) agents include synthetic compounds of different chemical groups: derivatives of barbituric acid (phenobarbital, benzonal, benzobamil, hexamidine); hydantoin derivatives (phenytoin), oxazolidinedione (Trimetin), succinimides (ethosuximide, pufemid) derivatives iminostilbena (carbamazepine), and others. More recently developed benzodiazepine drugs, which have particularly pronounced anticonvulsant effect (clonazepam, etc..). There was a fundamentally new group of antiepileptics - valproic acid and its salts (or atsediprol Konvuleks, et al.).
Depending on the chemical structure and pharmacological properties of different anticonvulsants (antiepileptic) drugs occurs mainly active in different forms of epilepsy. Thus, for large seizures (grand mal) used primarily phenobarbital and phenytoin; effective as hexamidine, carbamazepine, valproic acid. In psychomotor equivalents used mainly carbamazepine, phenytoin, hexamidine, clonazepam, and for small seizures (petit mal) - trimethyl, succinimides, benzodiazepines, valproic acid. Diazepam (sibazon) administered intravenously during status epilepticus. Other anticonvulsants are also used in non-epileptic nature of convulsive reactions.
As a general rule, a strict specificity for different forms of epilepsy, anticonvulsants have not. The same formulation may be effective to varying degrees in different forms of epilepsy. However, the generic type of the preparation, sufficiently effective in all forms and manifestations of epilepsy unavailable. Therefore, often simultaneously prescribed different antiepileptic drugs in various combinations, and are replacing one another drug if necessary.
The mechanism of action of antiepileptic drugs has not been studied. Note the possibility of reducing the under the influence of these drugs neuronal excitability epileptic focus. Recently, much attention is given to studying the role of neurotransmitters in the pathogenesis of epilepsy. It is believed that neurons of hypersensitivity and membrane potentials instability leading to spontaneous discharge, can be caused by an increased concentration of stimulating neurotransmitter of the central or decrease in the content of inhibitory neurotransmitters. In connection with this study the role of these mediators in the mechanism of action of antiepileptic drugs. Special attention is paid at the same uaminomaslenoy acid (GABA), which is the main inhibitory neurotransmitter in the CNS. We also study the role of another amino acid inhibitory neurotransmitter - glycine and excitatory amino acid neurotransmitters - glutamate and aspartate.
One of the current antiepileptic drugs, the effect of which is highly correlated with an increase in the concentration of GABA, is valproic acid (see. Atsediprol).
A special mechanism of action has diakarb (cm.), Which is an inhibitor of the enzyme carbonic anhydrase (see. Diuretics). It is used mainly for small forms of epilepsy (with occasional absences).
There are indications that the anticonvulsant effect of allopurinol (see.).
Antiepileptic drugs are usually used continuously and for a long time, so you need to carefully monitor their tolerance, to take into account their specific toxic properties, careful dosing, given the pharmacokinetic parameters.
The main types of side effects of these drugs are allergic, toxic and metabolic reactions. Allergic reactions, manifested not only in the form of skin and other common manifestations, but also in the form of increased frequency of seizures, mental deterioration, etc., Require the immediate lifting of the preparation used and its replacement by another drug group. Toxic reactions (psychiatric and neurological syndrome, leucopenia, and other hematologic disorders) are more common during long-term uncontrolled taking the drug. In such cases, the need for a gradual reduction of the dose and the appropriate detoxification therapy. Metabolic disorders (endocrine disorders, megaloblastic anemia, and others.) Require the immediate lifting of the preparation used and replace it with another. Particularly careful monitoring is necessary for the combined use of antiepileptic drugs, especially in patients with residual symptoms of organic brain diseases transferred.
3amenu one another antiepileptic should be performed gradually, reducing the dose of the drug previously used and replacing it with a new drug in increasing doses. To avoid decorations seizures must be ensured that between the drugs prescribed and re-used earlier, the relation of dose equivalent in potency. For different products, these relations are different. For example, the equivalent ratio of doses of certain drugs in doses of phenobarbital (taken as 1) up to difenina about 1.4: 1; hexamidine to 3: 1; benzonala to 2: 1; hlorakona to 15: 1.
Cancel antiepileptic drugs in all cases must be carried out gradually (to prevent the development of seizures up to status epilepticus).
Be aware that antiepileptic drugs can pass through the placental barrier and teratogenic. In the foreign literature describes cases of congenital malformations in infants whose mothers which accept valppoat natpiya and carbamazepine in combination with sodium valproate, phenytoin or phenobarbital.
In some cases, the application of anti-epileptic drugs (phenobarbital, diphenylhydantoin, hexamidine, valproate, and others.) Developed folic acid deficiency, which requires replenishment of this vitamin. However, large doses of folic acid may impair the anticonvulsant action of these drugs and to promote frequent seizures.
Cases of vitamin K deficiency bleeding in newborns whose mothers took phenobarbital, hexamidine, phenytoin. If necessary prophylactically prescribed to pregnant taking antiepileptic drugs, drugs of vitamin K (under the control of blood coagulation system).