What is a common IV dosing range for phenytoin used in status epilepticus?

• A. 10–12 mg/kg IV slowly
• B. 15–20 mg/kg IV slowly
• C. 100–150 mg IV
• D. 5–10 mg/kg IV

Answer: (B)

In status epilepticus you need a loading dose of IV phenytoin to rapidly achieve therapeutic brain concentrations. The standard approach is 15–20 mg/kg given IV and infused slowly. This weight-based dosing ensures an adequate amount reaches systemic circulation to control seizures while keeping the infusion rate low enough to minimize cardiovascular side effects. Typically, the infusion is run at a slow rate (to about 50 mg per minute or slower) because rapid administration can cause hypotension and arrhythmias.

Why this range fits best: it balances efficacy and safety for an urgent situation requiring quick seizure control, whereas too small a dose would be subtherapeutic and unlikely to halt ongoing seizures, and a flat, non-weight-based dose doesn’t account for patient size. Also, note that phenytoin is usually given as a loading dose; fosphenytoin can be used as an alternative with similar goals but is dosed differently (phenytoin equivalents).