How should phenytoin be administered intravenously to minimize adverse effects?

• A. Rapid IV push
• B. Intermittent intravenous infusion
• C. Oral administration only
• D. Subcutaneous injection

Answer: (B)

Phenytoin IV dosing must be slow to prevent cardiovascular and local adverse effects. Giving it as a rapid IV push can cause sudden, high plasma levels that lead to severe hypotension and arrhythmias, as well as irritation at the vein. Administering it as an intermittent intravenous infusion allows the drug to enter the bloodstream gradually, reducing these risks. Use normal saline as the diluent, and avoid dextrose-containing solutions, since phenytoin can precipitate. In adults, keep the infusion rate well controlled (not a rapid push), and monitor the patient during administration. Subcutaneous injection isn’t appropriate due to poor absorption and tissue injury, and oral administration isn’t addressing the IV route. Therefore, intermittent IV infusion is the best method to minimize adverse effects.