Final answer:
The nurse's priority action is to assess the client for adverse reactions and closely monitor their condition after administering orally dissolving mirtazapine through a PEG tube instead of the sublingual route.
Step-by-step explanation:
The nurse's priority action after accidentally administering orally dissolving mirtazapine through a client's percutaneous endoscopic gastrostomy (PEG) tube instead of the prescribed sublingual route is to assess the client for adverse reactions and closely monitor their condition.
The nurse should observe the client for any signs of an allergic reaction, such as difficulty breathing, swelling of the face, or rash, and seek medical assistance if necessary. Additionally, the nurse should monitor the client's vital signs, including heart rate and blood pressure, as well as any respiratory distress or changes in mental status.
The nurse should also document the incident and report it to their immediate supervisor as per the facility's protocol for medication errors. This ensures proper documentation and follow-up actions are taken to prevent similar errors in the future.