phenytoin (Dilantinl®)
Anticonvulsant
Antidysrhythmic (Class I-B)
Phenytoin (a hydantoin derivative chemically similar to phenobarbital) is a drug of choice in controlling grand mal and focal motor seizure activity. 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. In this use, it is of the same class (IB) as lidocaine.
20-30 minutes for seizure disorders
As long as 15 days
Major motor seizures
Digitalis-induced dysrhythmias
Hypersensitivity
Bradycardia
Second and third degree heart block
Hypotension with rapid IV push (greater than 50 mg/min)
Cardiovascular collapse
Dysrhythmias
Respiratory depression
CNS depression
Ataxia
Nystagmus
Nausea and vomiting
Pain from injection site
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.
50 mg/ml in 2 and 5ml ampules, 2ml prefilled syringe
Use in-line filter
IV line should be flushed with 0.9% NS before and after the drug is administered.
IV: 1000 mg or 16 mg/kg slow push, not to exceed 1 g or rate of 50 mg/min
IV: 10-20 mg/kg slow push (< 0.5 mg/kg/min)
Pregnancy Safety: 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.
Use large, stable vein for injection (extravasation may cause tissue necrosis.