What are normal levels 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 a toxic phenytoin level?

Phenytoin serum concentration. Toxic concentration. 40 to 80 umol/L (10 to 20 mg/L) – Therapeutic. 80 to 120 umol/L (20 to 30 mg/L) – Horizontal nystagmus. 120 to 160 umol/L (30 to 40 mg/L) – Vertical nystagmus, diplopia, ataxia, slurred speech, tremor, hyperreflexia, drowsiness, nausea, vomiting.

What causes 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.

How do I raise my phenytoin level?

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. If the phenytoin concentration is >16 mcg/mL, any change may result in a significant increase in serum level and should be done very carefully.

When should phenytoin levels be checked?

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.

What are the signs and symptoms of chronic phenytoin toxicity?

Intoxication manifests predominantly as nausea, central nervous system dysfunction (particularly confusion, nystagmus, and ataxia), with depressed conscious state, coma, and seizures occurring in more severe cases.

What happens when your Dilantin level is low?

DILANTIN may cause other serious side effects including: Low blood count which could increase your chance of getting infections, bruising, bleeding and increased fatigue. Softening of your bones (osteopenia, osteoporosis, and osteomalacia) can cause your bones to break (fractures). High blood sugar (hyperglycemia).

When do you draw a phenytoin level?

Levels can be drawn at the point of admission, regardless of the patient’s normal dosing time. In normal healthy subjects after dose adjustment, the phenytoin level should be drawn within six to seven days with subsequent doses of phenytoin adjusted accordingly.

When is corrected phenytoin level used?

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.

How should phenytoin treatment be monitored?

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.