What is phenytoin serum levels?

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.

How do you assess if phenytoin levels are therapeutic?

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 the minimum effective concentration of phenytoin?

General: Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations may be necessary for optimal dosage adjustments—the clinically effective serum level is usually 10–20 mcg/mL.

What can cause low phenytoin levels?

Drugs which may decrease phenytoin levels include: carbamazepine, chronic alcohol abuse, reserpine, and sucralfate. Moban® brand of molindone hydrochloride contains calcium ions which interfere with the absorption of phenytoin.

What causes high phenytoin levels?

Phenytoin toxicity can occur from an increase in the daily dose of phenytoin, changes in the formulations or brands as well as changes in the frequency of administration. It can also occur when patients are started on new medications that interact with the metabolism or binding capacity of phenytoin to plasma proteins.

When should phenytoin levels be corrected?

Corrects serum phenytoin level for renal failure and/or hypoalbuminemia. Use in patients with albumin ≤3.2 g/dL (32 g/L). The “Sheiner-Tozer Equation” is the official name of this correction.

What happens if you take too much phenytoin?

An overdose of phenytoin can be fatal. Overdose symptoms may include twitching eye movements, slurred speech, loss of balance, tremor, muscle stiffness or weakness, nausea, vomiting, feeling light-headed, fainting, and slow or shallow breathing. Avoid drinking alcohol while you are taking phenytoin.

What are the long term side effects of phenytoin?

Long-term use of phenytoin also has been found to cause weakening of the bones. Bone disease is even more likely if a combination of seizure medicines is used….The most common ones affect appearance:

• overgrowth of the gums.
• excessive hair on the face or body.
• acne.
• coarseness of facial features.

What is phenytoin used to treat?

Phenytoin is a medicine used to treat epilepsy. It can also be used to treat trigeminal neuralgia, a type of nerve pain that affects your face. Phenytoin is available on prescription. It comes as tablets that can be chewed or dissolved in water, capsules and a liquid that you swallow.

What does phenytoin do to the brain?

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. It works by decreasing abnormal electrical activity in the brain.

Why is phenytoin given at night?

For example, if the delayed-action phenytoin is taken in the evening in place of ordinary phenytoin, it might be hoped that it would produce by the next morning higher blood and tissue concentrations of phenytoin than would the ordinary prepara- tion, thus reducing the risk of an early morning epileptic seizure.

What is the percentage of phenytoin in the blood?

The range for percent free phenytoin is 8% to 14%. However, response and side effects will be individual. In patients with renal failure, total phenytoin is likely to be less than the therapeutic range of 10.0 to 20.0 mcg/mL. Severe toxicity occurs when the total blood concentration exceeds 30.0 mcg/mL.

How to calculate L.O.’s free phenytoin concentration?

1 What is L.O.’s free phenytoin concentration? Free = Total * ff = 9 * 0.172 = 1.5 mcg/mL 2 Is L.O. in therapeutic range? Yes, free level is within range of 1-2 mcg/mL, and total is within her specific goal range of 5.8-11.6 mcg/mL. 3 Next steps? Leave dose as is and recheck total level in another 7 days.

What is the CPT for phenytoin free serum?

Phenytoin, Free, Serum or Plasma TEST: 070763 CPT: 80186

What should the phenytoin level be in a nursing home?

In elderly nursing home patients or critically ill trauma patients with hypoalbuminemia: corrected phenytoin concentration = observed phenytoin concentration / ((0.25 x albumin) + 0.1) Alternatively, free phenytoin and total phenytoin levels drawn at the same time. The total phenytoin level should be close to the free phenytoin level x 10.