Phenytoin

Phenytoin is a first generation antiepileptic. It is used to treat tonic-clonic seizures. In other words these are seizures involving sudden onset stiffening accompanied by muscle contractions and spasms.

How does phenytoin work?

The mechanism of action of phenytoin involves regulation of the sodium channels. It reduces sodium access into the neuron and therefore the excitability of the neuron.

Do they have contraindications or precautions?

Phenytoin can have gastrointestinal effects (nausea, vomiting). At high dose it is also associated with a risk of the cerebellar syndrome (coordination problems) and visual disturbance. It can also cause skin problems (urticaria, erythema). More rarely it can be associated with a risk of anaemia.

Sources:

• Merck Manual, 4^th edition
• Institute for pharmaceutical and biological sciences – Lyon faculty of pharmacy