Product
Phenytoin is commercially available in tablet, injection, and infusion forms (phenhydane, phenytoin gerot). It has been approved in many countries since 1960.
Structure and properties
Phenytoin or 5,5-diphenylhydantoin (C15H12N2O2, Mr = 252.3 g/mol) exists as a white crystalline powder that is practically insoluble in water. The sodium salt phenytoin sodium, which is present in parenteral dosage forms, is soluble in water.
Effects
Phenytoin (ATC N03AB02) has anticonvulsant properties. Effects are due to membrane stabilization of central and peripheral nerves.
Indications
For the treatment of epilepsy, seizures of other causes, trigeminal neuralgia, and seizure treatment and prevention in traumatic brain injury. Another indication is cardiac arrhythmias (not approved in many countries).
Contraindications
- Hypersensitivity
- Certain cardiovascular diseases
- Severe damage to the blood cells and bone marrow.
Full details precautions and interactions can be found in the drug label.
Interactions
Phenytoin has a high potential for interaction. It is metabolized by CYP2C9 and CYP2C19 and is an inducer of CYP3A4.
Adverse effects
The most common potential adverse effects include fatigue, gait disturbances, excitability, tremor, movement disorders, speech disorders, intellectual performance disorders, dizziness, headache, visual disturbances, gum growths, and taste disturbances.
