When administering Dilantin IV, which practice is correct?

• A. Question the prescription since 7 mcg/mL is above the therapeutic level.
• B. Dilute the medication and flush the tubing before and after with normal saline.
• C. Administer the medication undiluted in the port closest to the intravenous site.
• D. Determine the time when the patient took the last oral dose of Dilantin.

Answer: (B)

When giving IV phenytoin, the key practice is to dilute the medication in normal saline and flush the tubing with saline before and after administration. Phenytoin has limited IV solubility and can precipitate if given undiluted or in dextrose-containing solutions, which can damage the vein and lead to poor delivery of the dose. Diluting in saline reduces the risk of precipitation, and flushing before and after helps keep the line clear and ensures the full dose is delivered.

Giving the medication undiluted, especially through a port near the IV site, increases the risk of local irritation and precipitation, so that approach isn’t correct. The timing of the last oral dose isn’t the primary concern for the IV administration technique, and the statement about the numeric level being above the therapeutic range isn’t accurate—phenytoin’s typical therapeutic range is roughly 10–20 mcg/mL, so a level of 7 would be subtherapeutic, not indicating a need to change the IV administration method.