When should you do a phenytoin level?
When should you do a phenytoin level?
A level can be taken 2-4 hours following an IV loading or top-up dose (12-24 hours for oral doses) and levels should then be monitored every 24 hours until control is achieved and concentration has stabilised.
What happens if phenytoin level is high?
The neurotoxic effects are concentration dependent and can range from mild nystagmus to ataxia, slurred speech, vomiting, lethargy and eventually coma and death. Paradoxically, at very high concentrations, phenytoin can lead to seizures.
How long will it take for the toxic levels of phenytoin to fall within the therapeutic range?
The plasma half-life in man after oral administration of phenytoin averages 22 hours, with a range of 7 to 42 hours. Steady-state therapeutic levels are achieved at least 7 to 10 days (5–7 half- lives) after initiation of therapy with recommended doses of 300 mg/day.
How long does phenytoin take to work?
How long does it take for phenytoin (Dilantin) to start working? It take about 7 to 10 days for the levels of phenytoin in your body to stabilize (reach “steady-state”) on a normal starting dose. Then your provider will gradually increase the dose to an appropriate amount.
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.
What is the half life of phenytoin?
Clinicians all know that, in general, the half-life of phenytoin is about 22 hours and that the volume of distribution of phenytoin is about 0.75 L/kg (1,2).
What is the therapeutic range is for phenytoin?
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.
What is the therapeutic range for phenytoin?
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).
When should I restart phenytoin after toxicity?
Phenytoin therapy should be stopped in all cases, and if toxicity continues to resolve, a serum level may be reassessed in 2 to 3 days to guide resumption of therapy. Patients with significant or persistent complications following the intravenous administration of phenytoin should be admitted.
What is a sub therapeutic level for Dilantin?
The therapeutic range is 10-20 mcg/mL. Total phenytoin levels (mcg/mL) and typical corresponding signs and symptoms are as follows: Lower than 10 – Rare. Between 10 and 20 – Occasional mild nystagmus.
What is the effect of phenytoin in pregnancy?
If phenytoin is taken by the mother in the first trimester, there is approximately a 5 to 10 percent chance that the baby could be born with a combination of birth defects known as the Fetal Hydantoin Syndrome. Babies with this syndrome may be born with some of the following health problems: Growth deficiency.
How does phenytoin affect fetus?
Today, the known potential adverse effects of phenytoin on the fetus include facial clefting, vitamin K and D deficiencies, heart malformations, limb deformities, and neurologic defects.
How do you adjust phenytoin levels?
A rough guide to making an adjustment to the daily dose that should increase a serum level without leading to supratherapeutic / toxic levels is: If the phenytoin concentration is < 7 mcg/mL, the dose may be increased by 100 mg/day. If the phenytoin concentration is 7-12 mcg/mL, the dose may be increased by 50 mg/day.
What is considered high phenytoin level?
Toxic phenytoin levels are defined as greater than 30 µg/mL. Lethal levels are defined as greater than 100 µg/mL. The reference range of free phenytoin is 1-2.5 µg/mL. In patients with renal failure associated with hypoalbuminemia, free phenytoin levels may be more accurate than total phenytoin levels.
What is the therapeutic serum range of phenytoin?
Obtain a serum phenytoin level. The therapeutic range is 10-20 mcg/mL.
What is the pregnancy risk category of phenytoin?
AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage.
Does phenytoin cause floppy baby syndrome?
Fetal hydantoin syndrome is a characteristic pattern of mental and physical birth defects that results from maternal use of the anti-seizure (anticonvulsant) drug phenytoin (Dilantin) during pregnancy. The range and severity of associated abnormalities will vary greatly from one infant to another.
What pregnancy risk category is phenytoin?
How do you titrate phenytoin?
If the phenytoin concentration is < 7 mcg/mL, the dose may be increased by 100 mg/day. If the phenytoin concentration is 7-12 mcg/mL, the dose may be increased by 50 mg/day. If the phenytoin concentration is >12 mcg/mL, the dose may be increased by 30 mg/day.
When to correct phenytoin level?
You have fast,uncontrollable eye movements or double vision.
When to measure phenytoin level?
swelling of the gums and/or lymph nodes
When to check phenytoin levels?
On initiating therapy
When to obtain phenytoin level?
Amikacin: Draw peak 30 minutes after a 30 infusion or 60 minutes after an IM injection.