Phenytoin Drug Flashcards

Study Notes

Trade Name

Phenytoin is commonly marketed under the trade name Dilantin.

Drug Class

It belongs to the anticonvulsant class, primarily used for seizure control.

Pregnancy Category

Classified as Category C, indicating potential risks during pregnancy.

Usage

Effective in treating tonic-clonic seizures as well as simple and complex partial seizures in individuals with no previous treatment.

Dosage: Adults

Initial dosage is 125 mg in suspension or 100-125 mg in tablet form taken three times daily, with adjustments made every 7 to 10 days based on tolerance and needs.

Dosage: Children

Initial dosage for children is 5 mg/kg daily, usually divided into two or three doses. Maintenance dosage ranges from 4 to 8 mg/kg daily, with a maximum of 300 mg daily.

Mechanism of Action

Regulates voltage-dependent sodium and calcium channels in neurons to limit seizure spread and onset. It enhances the sodium-potassium ATP activity and inhibits calcium movement across neuronal membranes, stabilizing neurons.

Contraindications

Includes conditions like Adams-Stokes syndrome, hypersensitivity to phenytoin, SA block, second or third-degree heart block, and sinus bradycardia.

Adverse Reactions

CNS effects: Ataxia, confusion, dizziness, and depression.
CV complications: Cardiac arrest and hypotension.
EENT issues: Amblyopia, gingival hyperplasia, and tinnitus.
GI disturbances: Nausea, vomiting, and abdominal pain.
GU problems: Renal failure and priapism.
Hematologic reactions: Agranulocytosis and platelet issues.
Skin conditions: Exfoliative dermatitis and Stevens-Johnson syndrome.
Other: Weight changes and lupus-like symptoms.

Nursing Considerations

Patients of Asian ancestry with the HLA-B 1502 variant are at risk for severe dermatologic reactions.
Preferred administration routes are oral and I.V., with caution against I.M. administration.
Patients with swallowing difficulties should use rapid-release capsules mixed with food or fluid.
Monitor blood pressure and ECG continuously during I.V. administration. Flush with saline to reduce vein irritation.
Separate the administration of phenytoin from antacids and calcium salts by at least 2 hours to avoid absorption issues.
Regularly monitor blood phenytoin levels, aiming for a therapeutic range of 10 to 20 mcg/L.
Keep track of hematologic status as phenytoin may induce blood dyscrasias.

Description

This quiz includes essential flashcards on Phenytoin, covering trade name, drug class, pregnancy category, usage, and dosage. Perfect for medical students and healthcare professionals needing a quick review of this anticonvulsant medication.