It was developed as an alternative anticonvulsant that would cause less sedation than barbiturates. Phenytoin appears to inhibit the spread of seizure activity by inhibiting sodium influx into neurons, thereby stabilizing the neuron's threshold against excitability caused by excess stimulation. Phenytoin has also been used to treat digitalis-induced atrial and ventricular dysrhythmias by stabilizing the sodium influx in Purkinje fibers of the heart, decreasing abnormal ventricular automaticity, and decreasing the refractory period. Cardiovascular collapse Dysrhythmias Respiratory depression CNS depression Ataxia Nystagmus Nausea and vomiting Pain from injection site Drug Interactions Anticoagulants, cimetidine, sulfonamides, and salicylates may increase serum phenytoin levels.
Chronic alcohol speeds metabolism of the drug.
Lidocaine, propranolol and other beta blocking agents may increase cardiac depressant effects. Xanthines may result in decreased phenytoin absorption Precipitation may occur when mixed with dextrose containing solutions. Incompatible with many solutions and medications. Not established Phenytoin may normally have slight yellow color Carefully monitor vital signs Venous irritation can occur due to alkalinity of the solution. Use with caution in patients with pulmonary, cardiovascular, hepatic or renal insufficiency.