Epilepsy refers to a group of disorders characterized by seizures due to abnormal electrical activity in the brain that temporarily disrupts the brain's normal functioning. The frequency and severity and particular symptoms of epileptic seizures vary with the different types of epilepsy. The Merck Manual states that no one drug controls all types of seizures: dosages and medication(s) must be tailored to each patient, and some patients might need more than one type of medicine to control their seizures.
Carbamazepine
According to the Merck Manual, carbamazepine is a front-line drug for generalized tonic-clonic seizures (generalized meaning the patient loses consciousness; tonic-clonic meaning rapid contraction and relaxation of the affected muscles; also known as grand mal seizures) and partial seizures (in which patient remains conscious) with or without secondary generalized seizures.
Topiramate
Topiramate is a newer anti-convulsant, useful for generalized tonic-clonic seizures. Although no more effective than carbamazepine, according to the Merck Manual topiramate causes fewer side effects and patients tend to tolerate it better. Unlike many other anti-convulsants, the absorption of topiramate is not affected by food. Topiramate controls seizures through a few different mechanisms. It blocks sodium channels in neurons, preventing abnormal electrical activity; it enhances the activity of the neurotransmitter GABA, which inhibits neuron activity; and it antagonizes receptors in the brain that become hyperactive during seizures.
Phenytoin
Like cabamazepine and topiramate, the anti-convulsant phenytoin treats generalized tonic-clonic seizures and partial seizures with or without secondary generalized seizures. Phenytoin works by stabilizing the membranes of nerve cells and regulating the flow of sodium ions in and out of cells in the part of the brain that controls muscle contractions. According to the Merck Manual, about 86 percent of patients have fewer seizures when blood levels of phenytoin reach more than 15 mcg/ml.
Valproate
Valproate is a front-line drug for generalized tonic-clonic seizures, and a useful secondary drug for patients with partial seizures who do not improve in response to a single drug. Valproate also effectively treats both typical and atypical absence seizures (loss of consciousness, with an abrupt stop to activity; though patients might jerk they usually do not fall) atonic seizures (loss of consciousness and brief total loss of muscle function, causing collapse) and juvenile myoclonic epilepsy (an epilepsy syndrome with rapid, jerking seizures (myoclonic), tonic-clonic seizures, and absence seizures). Valproate works by increasing the availability of the neurotransmitter GABA which quiets neurons in the brain.
