Phenytoin

Category: pharmacological

Aliases: Dilantin, Phenytek

Pharmacological Mechanism

Use-dependent Na⁺ channel blocker — stabilises inactivated state → prevents high-frequency neuronal firing characteristic of seizure. Saturable metabolism (Michaelis-Menten) → small dose increases cause disproportionate level rises. CYP inducer + substrate.

Half-Life (t½)

PO: 19h, IV: 19h

Dosing Guidelines

• PO: Typical 367mg (Range: 300 - 500 mg)
• IV: Typical 367mg (Range: 300 - 500 mg)

Target Organ Systems

• nervous

Interactions

• Hormonal contraceptives
• Atorvastatin
• Quetiapine