Methadone for Cancer Pain

Opioids in cancer-related pain: current situation and outlook

PURPOSE

Despite progress in treatments, cancer pain remains underestimated, poorly assessed and under-treated. Prescribing strong opioids, because of their specificities, requires precision in management considering their pharmacology but also a clear understanding of recommendations. Some clinicians highlight the risk of addiction, excessive sedation and respiratory depression and their need for information. Our objective in this review is to suggest some clinical guidance for the positioning and daily use of opioids within cancer pain management.

METHODS

Critical reflection based on literature analysis and clinical practice.

RESULTS

Strong opioids may be initiated as soon as pain diagnosis is defined. Factors to consider are pain aetiology, opioid pharmacokinetics and pharmacodynamics, genetic polymorphism, physiology (age, gender, weight and pregnancy), comorbidities (especially renal, hepatic, cardiovascular diseases), chronobiology, environmental factors, medication interference and treatment adherence. Achieving the best-balanced opioid treatment for background pain is complex, mainly due to the variable benefit/risk ratio between individuals and the experience of breakthrough cancer pain. Opioid initiation alongside a dynamic reassessment of pain should be fully integrated into the patient's management to optimise analgesia. The efficacy and safety of a strong opioid treatment need to be re-evaluated and adapted to individuals constantly as it varies over time.

CONCLUSIONS

Cancer pain is multimorphic and permanently changing due to disease evolution, curative treatments and disruptive events (concomitant treatments, pain from associated disease, comorbidities and complications, modifications of the environment). Well-managed opioids are the cornerstone of a complex environment requiring multidisciplinary dynamic assessments integrated into the patient's care pathway.

Nephrotoxicity of methadone: a systematic review

Background

Methadone is commonly administered for chronic pain relief and treatment of opioid dependence. Concurrent with its increased consumption, toxicities and fatalities have increased. One of the adverse effects of opioid analgesics, including methadone, is that of nephrotoxicity. Opioids can have an effect on renal function through several different mechanisms.

Methods

We searched common bibliographical databases for the terms methadone, toxicity, poisoning, kidney, renal, and nephrotoxicity and summarize our findings in this review.

Results

Methadone can have both direct and indirect effects on the kidney. These effects include rhabdomyolysis (leading to acute kidney injury), volumetric changes, renal lipidosis and amyloidosis, kidney growth during pregnancy, and kidney transplant rejection.

Conclusion

Improved understanding of the effects of methadone on kidney function can promote safer and more confident use of the drug.

Methadone rotation for cancer patients with refractory pain in a palliative care unit: an observational study

BACKGROUND

Methadone has been reported to be as effective as morphine for cancer pain management. It is commonly used as an alternative opioid in case of insufficient relief.

OBJECTIVE

Our aim was to assess efficacy and tolerance of opioid rotation to methadone for refractory cancer pain management in palliative care unit (PCU) inpatients.

METHODS

All the patients undergoing opioid rotation to methadone from 2008 to 2011 in two PCUs (Lyon and Nice, France) were included. Pain assessments were undertaken on day 0 (D0), day 3 (D3), day 7 (D7), and day 14 (D14) using a visual analogue scale (VAS; 0-10) and the Douleur Neuropathique 4 (DN4) scale for neuropathic pain. Patients reported pain relief using a 4-point Likert scale (1=no relief; 4=important relief ).

RESULTS

Nineteen patients (7 females) with a median age of 55 (Q1-Q3; 44-58) underwent methadone rotation. The most common type of cancer was gastrointestinal. Seventeen patients had a diagnosis of mixed pain syndromes. Morphine equivalent daily dose (MEDD) prior to switching was 480 mg (Q1-Q3; 100-1021), and at least two nonmethadone opioid rotations had already been done for 13 patients. Between D0 and D7, the VAS score decreased by 4 points (p<0.001). The DN4 score became negative on D7 for 11 of 17 patients (65%). On D7, 16 of 18 patients (89%) expressed moderate to greater than moderate pain relief. Methadone was discontinued in one patient on D7 because it was deemed ineffective and for 8 patients, who were unable to take oral drugs, it was discontinued after D14.

CONCLUSION

Our results suggest that methadone is effective and well tolerated for refractory cancer pain.