Final answer:
The nurse should administer the fentanyl to the client using a parenteral route such as intravenous or intramuscular injection.
Step-by-step explanation:
The nurse should administer the fentanyl to the client using a parenteral route such as intravenous or intramuscular injection.
This is because fentanyl is not well absorbed in the gastrointestinal (GI) tract, making oral administration less effective. By administering the drug directly into the bloodstream or muscle, the nurse can ensure that the desired plasma levels of the medication are achieved.