What is the mechanism of action of phenytoin?

Phenytoin is primarily recognized as an antiepileptic medication that works by inhibiting fast sodium channels in neurons. This unique mechanism contributes to its ability to stabilize neuronal membranes and reduce the excitability of neurons. When phenytoin binds to these sodium channels, it slows the rate of recovery from inactivation, leading to a decrease in neuronal firing frequency and reducing the likelihood of seizure activity.

The effectiveness of phenytoin in various seizure disorders, particularly focal and generalized seizures, stems from this mechanism of action. By preventing excessive sodium influx during depolarization, phenytoin helps maintain a stable resting membrane potential, which is crucial for normal neuronal function and excitability.