ANTICONVULSANT DRUGS

Epilepsy is a chronic central nervous system disorder in with brief episodes of seizures appear with or without the loss consciousness. Epileptic seizures are spontaneous, rec chronic and paroxysmal with a discontinuity of symptoms wide interval between seizures. There may be other sympt such as convulsive movements of arms or legs, increase muscle tone, causing locked jaw, followed by decreased mus tone, frothing at the mouth, the eye-ball moving upwards attack of epilepsy may occur at any time and it is usually difficult to predict its onset. However, some patients get a warning signal (aura) in the form of flashes of light or sounds.

Anticonvulsant drugs are used to prevent and co epileptic seizures. An epileptic seizure has been defined paroxysmal discharge of cerebral neurones accompanied clinical phenomenon apparent to the patient or to an obse Epilepsy is a condition characterized by a recurrence of st seizures. Thus, epilepsy is a disease which arises due to disorders of central nervous system.

There are two useful drugs which would depress them cortex (prevent convulsions) and the sensory cortex (prod sleep). The bromides, phenobarbital, and diphenylhyda have been used to control seizures. They demonstrate sedation may be dissociated from anticonvulsant activity in various types of epilepsy. Each type of epilepsy may distinguished by clinical and electroencephalographic ma and each shows different results with various classe anticor sant drugs.

Epileptic seizures are classified into generalized and partial seizures. The generalized seizures are further sub-divided as follows :

1. Grand mal (Tonic-clonic) : Sudden loss of consciousness followed by general muscle spasms lasting for an average of 2 to 5 minutes. The frequency and the severity of attacks are different.

2. Petit mall (Abences): When there is sudden, brief loss of consciousness with minor movements of the head, the eyes and the extremities, lasting for about 5 to 10 seconds, it is known as petit mal. The patient is immediately alert, and ready to continue normal activity. There may be many episodes in a day. The highest incidence of petit mal is found in children.

The partial (focal, local) seizures are concerned with motor, sensory or automatic symptoms and those of complex symptoms psychomotor seizures).

In psychomotor seizures automatic. patterned movements lasting from 2 to 3 minutes occur. Amnesia is common and general. There is no remaining of memory of the incident. This state is sometimes confused with psychotic behaviour.

Barbiturates, hydantoins, oxazolidinediones, succinimides and some other compounds are used as anticonvulsant drugs. The drugs acting as selective depressants of convulsant activity have a common structural feature, except primidone.

The choice of antiepileptic agent for the treatment of epilepsy is determined by the type of seizure. For grand mal seizures and partial seizures, phenytoin, carbamazepine, or alproic acid is generally used with phenobarbitone or primidone as alternatives. For petil mal usually ethosuximide or valproic acid are used. Clonazepam, ethosuximide or valproic acid are employed to treat myoclonic seizures. In general, therapy with single antiepileptic agent is preferred unless seizures of a mixed type are present.