THERAPEUTIC Tonic-clonic epilepsy, psychomotor, and focal, especially when the condition has not been controlled with the use of plain. Pharmacokinetics Phenytoin (difenhidantoína) Phenytoin exerts its seizure activity without causing general CNS depression. Limits the development of the maximum activity of the crisis and reduce the spread of the electoral process from an active focus. Can induce complete remission of generalized tonic-clonic seizures and some other partial, but not completely eliminate the sensory aura or other prodromal signs. The maximum concentration after a single dose may occur in plasma in a period ranging between 3 and 12 hours after administration. A once absorbed is rapidly distributed in all tissues. Largely binds to plasma proteins (approximately 90%), mainly albumin. The concentration in the cerebrospinal fluid is equal to the free plasma fraction. Less than 5% of phenytoin is excreted unchanged in the urine, the remainder is metabolized mainly by the action of hepatic microsomal enzymes. Parahidroxifenílico derivative is the major metabolite and is inactive. Plasma half-life of 6 to 24 hours. At higher concentrations it is apparent elimination dose dependent. Plasma half-life increases with concentration (dose). Phenobarbital: Phenobarbital is a barbiturate and a long duration of the most widely used as anticonvulsant. Its efficiency is higher in tonic-clonic seizures. Is well absorbed from the gastrointestinal tract. The presence of food in the stomach decreases the rate of absorption, but its bioavailability. Plasma concentrations were detected between 2-3 hours after administration and binds to plasma proteins in 40-60%. Reversibly depresses the activity of all excitable tissues, especially the CNS which is very sensitive to it. The drug concentration in the cerebrospinal fluid is equal to the free phenobarbital concentration in plasma, crosses the placenta, fetal blood found in amounts similar to that of plasma. Phenobarbital is excreted unchanged in the urine to a limited extent (20-30%) and elimination rate may increase alkalinizing the urine. The rest is inactivated by hepatic microsomal enzymes. While the current trend is the use of single drugs, it is known that a large group of epileptic patients respond only to the association of these two drugs by enhancing their effect can reduce the dose. GENERAL PRECAUTIONS During the administration of this product should avoid intake of alcoholic beverages and the operation of vehicles and machinery.