The nurse prepares to administer a 1,000 mg loading dose of phenytoin IV to a client with a subarachnoid hemorrhage. Which consideration is most important when administering this dose?

Administering phenytoin requires applying knowledge of intravenous drug compatibility and cardiovascular safety profiles. The nurse must prioritize monitoring for life-threatening complications associated with rapid infusion, specifically focusing on the drug's narrow therapeutic index and its significant irritant properties. Choice A rationale Phenytoin is highly unstable and will precipitate if mixed with dextrose solutions. It must only be diluted with 0.9 percent sodium chloride. Incorrect dilution can lead to crystalline emboli and loss of drug efficacy during administration. Choice B rationale Intravenous phenytoin is a known vesicant that can cause purple glove syndrome if administered into small peripheral veins like those in the hand. Use of a large-bore catheter in a large vein or central line is preferred. Choice C rationale Rapid infusion of phenytoin can lead to severe cardiovascular collapse, including hypotension and fatal dysrhythmias. The infusion rate should not exceed 50 mg per minute to allow the heart to tolerate the drug's membrane-stabilizing effects safely. Choice D rationale The standard therapeutic range for phenytoin is 10 to 20 mcg per mL, not 20 to 30 mg per mL. Levels exceeding 20 mcg per mL often result in toxicity, characterized by nystagmus, ataxia, and decreased mental status.