CNS

¯ Epilepsy is one of the most common disorders of the brain, affecting about 50 million individuals worldwide. Epilepsy is a chronic and often progressive disorder characterized by the periodic and unpredictable occurrence of epileptic seizures that are caused by abnormal discharge of cerebral neurons. Epilepsy is not a disease, but a syndrome of different cerebral disorders of the CNS. This syndrome is characterized by paroxysmal, excessive, and hypersynchronous discharges of large numbers of neurons. These seizures may be identified on the basis of their clinical characteristics. These clinical attributes, along with their electroencephalographic (EEG) pattern, can be used to categorize seizures.

¯Seizures are basically divided into two major groups:

1. Partial (focal, local) seizures are those in which clinical or EEG evidence exists to indicate that the disorder originates from a localized origin, usually in a portion of one hemisphere in the brain.
2. Generalized seizures, the evidence for a local origin is lacking.

¯ The goal of therapy with an anticonvulsant agent is to have the patient seizure free without interfering with normal brain function. Thus, the selection of an anticonvulsant agent is based primarily on its efficacy for specific types of seizures and epilepsy.

¯They are used for the prevention of different types of epileptic seizures. They act through decreasing the electrical excitability at the site of epilepsy or at adjacent neurons.

Several classes of compounds belonging to different nuclei are used