Which statement about phenytoin administration is true?

• A. Has the most rapid onset of action of seizure medications
• B. Must be administered in dextrose
• C. Administration can result in hypertension
• D. Causes tissue vesication if infiltrated

Answer: (D)

Phenytoin given IV is a tissue irritant, and extravasation can cause significant local injury leading to tissue necrosis or vesication. The solution is alkaline and can damage surrounding tissues if it leaks out of the vein, so careful IV access, slow infusion, and using the proper diluent are essential. In practice, phenytoin is diluted in normal saline and infused slowly with monitoring because rapid administration can also cause hypotension or arrhythmias, not hypertension. It is not given in dextrose-containing solutions, which can cause precipitation, and it is not the fastest-acting antiseizure medication compared with benzodiazepines used for acute seizure control. The key takeaway is that infiltration or extravasation of IV phenytoin can produce tissue injury, making that statement true.