Renal Failure May Increase Need for Morphine Adjustment

VIENNA, Austria—Cancer pain patients with chronic renal failure are more likely than others to need changes in their morphine regimen, reported M. Escher, MD, of the Multidisciplinary Pain Center, University Hospital, Geneva, Switzerland. This retrospective study, reported at the 9th World Congress on Pain, reviewed medical records of 110 cancer patients who had been referred for a pain consultation and had been prescribed morphine.

Dr. Escher reported that 48% of patients required some type of adjustment to their morphine regimen, either a dosage change or change to another opioid (25% of patients were switched to a different opioid).

Adverse effects were the major reason for treatment adjustment and accounted for 53% of changes (Table). In 24% of cases, the treatment change was a reduction in morphine dose because pain was adequately controlled at lower doses. One interesting fact Dr. Escher reported is that a substantial number of patients (11%) refused to take morphine, thus necessitating a change in the treatment regimen.

Adverse events occurred in 37% of the total patient population. However, in about one third of these patients, no treatment adjustment was needed. The most common side effects in patients requiring treatment adjustment were nausea/ vomiting and sedation.

Dr. Escher found that patients with chronic renal failure (defined as creatinine greater than 101µmol/L or creatinine clearance less than 50 µL/min) were significantly more likely than those patients with normal renal function to need treatment adjustments (P = .05).

There were no significant differences in need for treatment adjustments relative to type of pain (nociceptive, mixed, or neuropathic).

“Chronic renal failure is the major factor associated with a therapeutic adjustment of morphine,” Dr. Escher concluded. “Adverse effects are the main, but not the only, reason for adjustment.”

He concluded that “morphine prescription needs individuation, and opi-oid rotation is an option to be considered when faced with some of these problems.”