Overview of Phenytoin
What is Phenytoin?
Preparation for Phenytoin
- No special preparation required
Why Get Tested for Phenytoin?
The Phenytoin Test is performed:
· To establish the therapeutic dosage for phenytoin in the blood
· To monitor phenytoin levels at regular intervals to maintain therapeutic concentration after starting treatment
· To check for phenytoin toxicity if toxicity symptoms appear
Understand more about Phenytoin
Phenytoin is a drug used mainly for the treatment of epileptic seizures. It is also used to treat convulsions and seizures caused due to neurosurgery. It may be prescribed in combination with other anticonvulsant medications like phenobarbital.
Phenytoin taken orally is absorbed in the intestinal tract and goes into the blood. In blood, most of it gets bound to plasma proteins like albumin and only a small portion remains free. Only the free phenytoin remains metabolically active and the phenytoin-protein complex remains inactive. Phenytoin blocks the excessive electrical conductivity between the neurons in the brain during seizures.
Phenytoin levels are affected by a number of factors including liver function, other drugs, levels of plasma proteins that form complex with it, and the age of the patient. Since phenytoin levels need to be maintained within a very narrow therapeutic range in blood, they are monitored regularly during treatment.
What Results of Phenytoin mean?
10 to 20 µg/ml (Children and adults)
8 to 15 µg/ml (Newborns)
Free phenytoin: 1 to 2 µg/ml
The therapeutic range of phenytoin may vary from person to person and due to a number of other factors. Hence, the therapeutic range is established for the patient at the beginning of treatment.
Lower phenytoin concentration than the therapeutic range makes the drug ineffective in treatment.
Higher phenytoin concentration than the therapeutic range induces symptoms associated with phenytoin toxicity.
Patient Concerns about Phenytoin
Frequently Asked Questions about Phenytoin