Routine Monitoring of QTc Interval as a Barrier for Efficient Use of Methadone in Palliative Care.

BACKGROUND: Methadone is a commonly prescribed opioid amongst cancer patients. It has unique pharmacological properties which can benefit in treating complex pain syndromes and neuropathic pain. However, strict guidelines have been created in a generalized manner for chronic pain and long-term survival patients. These guidelines, such as QT interval monitoring can lead to limitations for methadone use in patients with comfort associated goals. We present two cases of patients with metastatic cancer who were treated for pain with methadone and had to undergo opioid rotation due to abnormal QT interval.

CASE DESCRIPTION: Case one was a female with open ulcerated wounds due to metastatic breast cancer who presented with uncontrolled pain on her current opioid regimen. She achieved pain relief when rotated to methadone but a repeat electrocardiogram (ECG) a few months later showed QTc prolongation. She underwent opioid rotation with different medications, but her pain remained poorly controlled. Case two was a female with poorly controlled pain in setting of bilateral breast cancer. She presented with concerns for opioid induced neurotoxicity and was rotated to methadone. She achieved optimal pain relief. Few weeks later, her machine read QT interval was prolonged and she was rotated off methadone. ECG was manually read which showed a normal QT interval and she was restarted on methadone with pain relief.

CONCLUSION: In the palliative care setting, monitoring QTc per chronic pain guidelines may lead to uncontrolled pain and significant impact on quality of life.