# A 62-year-old client is being initiated on methadone 5 mg PO three times daily for chronic neuropathic pain. The client is also taking ondansetron and ciprofloxacin. Which is the priority nursing assessment and intervention plan?

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> url: https://mymerci.kr/pages/nclex_q.php?qn_id=375164&lang=en  
> language: en  
> subject: Adverse Effects/Contraindications/Interactions  
> category: PA

## Question

A 62-year-old client is being initiated on methadone 5 mg PO three times daily for chronic neuropathic pain. The client is also taking ondansetron and ciprofloxacin. Which is the priority nursing assessment and intervention plan?

## Option

1. Increase the dose every 12 hours until pain is controlled because methadone is short-acting.
2. Stop ondansetron and ciprofloxacin immediately because they cancel methadone analgesia.
3. Obtain a baseline 12-lead ECG to assess QTc, review the medication list for QT-prolonging agents (ondansetron, ciprofloxacin, amiodarone, antipsychotics), titrate slowly with a wait of at least 5 to 7 days between adjustments because of the long and variable half-life, monitor sedation and respiratory rate carefully especially after day 3, and educate that methadone is started low and increased slowly. **✔ Correct answer**
4. Methadone has no QT effect; ECG monitoring is unnecessary.

**Correct answer: 3**

## Explanation

Methadone is a long-acting mu-agonist with N-methyl-D-aspartate (NMDA) antagonism, useful for chronic pain and opioid use disorder treatment. Three pharmacologic pitfalls dominate NCLEX teaching: (1) variable, long elimination half-life (15 to 60 hours, much longer than the analgesic half-life of 4 to 8 hours) — accumulation is a major risk in days 3 to 7 after initiation or dose change, when respiratory depression peaks; titrate every 5 to 7 days, not daily; never instruct a patient to take more if pain is not controlled in the first days; (2) QTc prolongation and risk of torsades de pointes — obtain baseline ECG, repeat at 30 days and annually or with dose increases above 30 to 40 mg/day, with new symptoms, or when adding QT-prolonging drugs (ondansetron, fluoroquinolones such as ciprofloxacin, amiodarone, antipsychotics, certain antibiotics, methadone itself, electrolyte disturbances of low K and low Mg); avoid combinations when possible; (3) drug-drug interactions through CYP3A4 and CYP2D6 — phenytoin, rifampin, ritonavir, fluvoxamine, and many others alter methadone levels. Naloxone reversal may require an infusion because methadone outlasts naloxone. Increasing the dose every 12 hours, denying QT effect, and reflexively stopping interacting drugs without an alternative are unsafe.

## In-depth explanation

Slow titration plus QT vigilance plus respiratory surveillance peaking on days 3 to 7 is the methadone safety triangle. Stay alert to QT-prolonging combinations.

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