The therapeutic ranges for most adults have been established at 10.0-20.0 mcg/mL for total phenytoin (bound plus unbound) and 1.0-2.0 mcg/mL for free phenytoin (unbound only). This reference range for unbound phenytoin (free) was established based on an assumed 10% unbound drug fraction.
Does phenytoin have a narrow therapeutic range?
Phenytoin (brand name Dilantin) is an anticonvulsant medication used for the treatment of seizures (1). Phenytoin has a narrow therapeutic index—individuals that have supratherapeutic blood concentrations of phenytoin have increased risks of acute side effects.
What is a toxic phenytoin level?
Signs and symptoms of phenytoin toxicity typically correspond to the serum level, and progress from occasional mild nystagmus at 10-20 mcg/mL (the therapeutic range) to coma and seizures at levels above 50 mcg/mL (see Presentation and Workup).
Is phenytoin a therapeutic drug?
Phenytoin is an antiepileptic agent which is effective for tonic-clonic and focal seizures 1. It has a narrow therapeutic index and the relationship between dose and serum phenytoin concentration is non-linear.
What range of numbers should a Dilantin level fall between?
For Dilantin capsules, peak serum levels occur 4 to 12 hours after administration. Optimum control without clinical signs of toxicity occurs more often with serum levels between 10 and 20 mcg/mL, although some mild cases of tonic-clonic (grand mal) epilepsy may be controlled with lower serum levels of phenytoin.
What is the therapeutic range for phenobarbital?
The therapeutic range for adults taking phenobarbital is 15-40 micrograms/milliliter (mcg/ml) (65-173 micromole/liter) for seizure treatment, and 5-15 micrograms/milliliter (mcg/ml) (22-65 micromole/liter) for sedative-hypnotic use.
What is low therapeutic index?
Narrow therapeutic index drugs are drugs where small differences in dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions that are life-threatening or result in persistent or significant disability or incapacity.
When do you monitor phenytoin levels?
After a patient has received a loading dose of intravenous phenytoin, levels can be checked one hour after the dose. If loading is achieved by oral dosing, phenytoin levels can be checked 24 hours after the last dose10. This level can aid in determining maintenance dose or need to reload.
What is a sub therapeutic level?
Definition of subtherapeutic
: less than therapeutic : having, using, or being a dose that is below what is used for treating disease or producing an optimal therapeutic effect … with a fixed dose of 95 mg/kg/day, initial levels during the febrile phase were subtherapeutic (
What does a high Dilantin level mean?
Dilantin, or phenytoin, toxicity happens when you have high levels of Dilantin in your body that become harmful. Dilantin is a medicine that is used to prevent and treat seizures. Dilantin toxicity can lead to a coma.
What is the antidote for phenytoin?
There is no antidote, and there is no evidence that any method of gastrointestinal decontamination or enhanced elimination improves outcome. Activated charcoal should be considered if the patient presents early; however, the role of multiple-dose activated charcoal is controversial.
What are the usual signs of acute phenytoin toxicity?
Excessive self-medication, misunderstanding of the prescription order, and probable drug interaction were the three leading causes of acute phenytoin intoxication. Unsteady gait, dizziness/vertigo, nausea/vomiting, general weakness, and drowsiness were the most common presenting symptoms.
Why does phenytoin need therapeutic drug monitoring?
Therapeutic drug monitoring of phenytoin is necessary to ensure therapeutic and nontoxic levels. Hypoalbuminemia, renal failure, and interactions with other highly protein-bound drugs (e.g., valproic acid) alter protein binding of phenytoin.
What is phenytoin 100mg used for?
Phenytoin is used to control certain type of seizures, and to treat and prevent seizures that may begin during or after surgery to the brain or nervous system. Phenytoin is in a class of medications called anticonvulsants.
What is phenytoin used to treat?
Phenytoin is used to control seizures (convulsions), including tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures, in the treatment of epilepsy. It is also used to prevent and treat seizures that occur during brain surgery.
How do you treat high phenytoin levels?
Treatment / Management
Activated charcoal reliably binds phenytoin and prevents absorption. In acute ingestions, one dose of activated charcoal may be of benefit especially in large acute overdoses as phenytoin slows GI motility and absorption is delayed.
