Journal of pain & palliative care pharmacotherapy
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J Pain Palliat Care Pharmacother · Jan 2008
ReviewOpioid side effects and their treatment in patients with chronic cancer and noncancer pain.
Opioids are the foundation of standard analgesic regimens for moderate to severe pain due to life-threatening illnesses such as cancer, and are increasingly employed in chronic noncancer pain of the same severity. Opioids are frequently used for long periods in these populations, sometimes for years. However, side effects are common and may reduce quality of life, or become life threatening, and frequently cause patients to discontinue opioid therapy. ⋯ General management strategies include switching opioids ("opioid rotation"), discontinuation of concurrent medications that exacerbate side effects, and symptomatic treatment. In addition, recently recognized adverse events that occur after long-term opioid therapy are discussed. High-quality evidence is lacking for the treatment of most side effects, and the true incidence, underlying mechanisms, and clinical implications of long-term responses to opioid therapy are not yet fully understood.
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J Pain Palliat Care Pharmacother · Jan 2008
Case ReportsInconsistencies in opioid equianalgesic ratios: clinical and research implications.
Cancer pain is common, occurring in up to 60% of patients and opioid conversion may be required for effective pain management. Conversion from one opioid to another can be problematic due to differences in equianalgesic ratios found in established resources. This study explores the implications of using various published equianalgesic ratios when converting to a common opioid unit. ⋯ First, this study substantiates the use of these ratios as only guidelines for treatment. Second, it supports the need for well-designed, rigorous studies to evaluate opioid conversions. Third, this study demonstrates the need for a standard reporting system of opioid equianalgesic ratios employed in clinical trials.
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The described ratio for methadone conversion from oral route (PO) to parenteral route (PAR) is 2:1 and from PAR to PO is 1:2. Frequently, good control of pain with methadone is PR to PO. We use methadone as a function of opioid rotation and not in the context of mortality outcome and we have noted that the traditional ratio produces toxicity problems. We present our experience with patients who we converted from PAR to PO methadone and we recommend a conversion ratio of 0.7 (PO:PAR = 1:0.7), which approximates the bioavailability of the drug administered orally.