Phenytoin Ikapharmindo Mechanism of Action

Capsule: Drug Actions: Phenytoin sodium is an anticonvulsant that can be used for the treatment of epilepsy, the main work of phenytoin is in the motor cortex where spread of attack activity is inhibited, perhaps by increasing the flow of sodium out of nerve. Phenytoin sodium tends to stabilize the threshold against hyperexcitability caused by excessive stimulation or environmental changes that could reduce membrane sodium gradient.
Injection: Actions: Phenytoin Sodium is an anticonvulsant which is useful in the treatment of status epilepticus of the grand mal type. The primary site of action appears to be the motor cortex where spread of seizure activity is inhibited. Possibly by promoting sodium efflux from neurons, phenytoin tends to stabilize the threshold against hyperexcitability caused by excessive stimulation or changes capable of reducing membrane sodium gradient. This includes the reduction of post-tetanic potentiation at synapses. Loss of post-tetanic potentiation prevents cortical seizure foci from detonating adjacent cortical areas. Phenytoin reduces the maximal activity of brain stem centers responsible for the tonic phase of grand mal seizures.
Non-Therapeutic Effects: The toxicity signs associated with intravenous administration of Sodium Phenytoin are cardiovascular collapse and/or central nervous system depression. Hypotension may occur when the drug is administered rapidly by the intravenous route. The rate of administration is very important, it should not exceed 50 mg per minute (1 ml solution per minute). At this rate toxicity should be minimized. Severe cardiotoxic reactions and fatalities have been reported with atrial and ventricular conduction depression and ventricular fibrillation. Severe complications are most commonly encountered in elderly and gravely ill patients. Parenteral Phenytoin sometimes causes drowsiness, nystagmus, circumoral tingling, vertigo, nausea and rarely vomiting. These effects are usually observed at a plasma concentration above 20 mcg/ml which is just above the usual therapeutic plasma level.