Focal seizures: Mainly used to protect against the development of focal seizures with complex symptomatology (psychomotor and temporal lobe seizures). Also effective in controlling focal seizures with autonomic symptoms. Absence seizures: Not used in treatment of pure absence seizures due to risk for increasing frequency of seizures. However, can be used in combination with other anticonvulsants during combined absence and tonic-clonic seizures. Seizures during surgery: A 2018 meta-analysis found that early antiepileptic treatment with either phenytoin or phenobarbital reduced the risk of seizure in the first week after neurosurgery for brain tumors. Status epilepticus: Considered after failed treatment using a benzodiazepine due to slow onset of action. Other
Abnormal heart rhythms: may be used in the treatment of ventricular tachycardia and sudden episodes of atrial tachycardia after other antiarrhythmic medications or cardioversion has failed. It is a class 1b antiarrhythmic. Digoxin toxicity: Intravenous formulation is drug of choice for arrhythmias caused by cardiac glycoside toxicity. Trigeminal neuralgia: Second choice drug to carbamazepine. Special considerations
Phenytoin has a narrow therapeutic index. Its therapeutic range for an anticonvulsant effect is 10–20 μg/mL and for an antiarrhythmic effect 10–20 μg/mL. The most common cause of phenytoin intoxication is self‑medication, which accounts for more than thirty percent of the cases. Avoid giving intramuscular formulation unless necessary due to skin cell death and local tissue destruction. Elderly patients may show earlier signs of toxicity. In the obese, ideal body weight should be used for dosing calculations. Pregnancy: Pregnancy category D due to risk of fetal hydantoin syndrome and fetal bleeding.
Phenytoin (PHT), sold under the brand name Dilantin among others, is an anti-seizure medication. It is useful for the prevention of tonic-clonic seizures (also known as grand mal seizures) and focal seizures, but not absence seizures. The intravenous form, fosphenytoin, is used for status epilepticus that does not improve with benzodiazepines. It may also be used for certain heart arrhythmias or neuropathic pain. It can be taken intravenously or by mouth. The intravenous form generally begins working within 30 minutes and is effective for roughly 24 hours. Blood levels can be measured to determine the proper dose.Common side effects include nausea, stomach pain, loss of appetite, poor coordination, increased hair growth, and enlargement of the gums. Potentially serious side effects include sleepiness, self harm, liver problems, bone marrow suppression, low blood pressure, and toxic epidermal necrolysis. There is evidence that use during pregnancy results in abnormalities in the baby. It appears to be safe to use when breastfeeding. Alcohol may interfere with the medications effects.Phenytoin was first made in 1908 by the German chemist Heinrich Biltz and found useful for seizures in 1936. It is on the World Health Organizations List of Essential Medicines. Phenytoin is available as a generic medication. In 2017, it was the 221st most commonly prescribed medication in the United States, with more than two million prescriptions. Medical uses
Seizures
Tonic-clonic seizures: Mainly used in the prophylactic management of tonic-clonic seizures with complex symptomatology (psychomotor seizures). A period of 5–10 days of dosing may be required to achieve anticonvulsant effects.