OPIOID ROTATION FOR TOXICITY REDUCTION IN TERMINAL CANCER-PATIENTS

Accumulation of active (toxic) metabolites of opioids might explain ca ses of opioid toxicity when high doses are used for long periods of ti me. Other mechanisms of late toxicity of opioids may be found at the r eceptor level Whatever the cause a change of opioids using equianalges ic doses can be expected to improve symptoms of toxicity in some patie nts, while maintaining pain control. We reviewed the experience with t his technique in patients admitted to the Palliative Care Unit of the Edmonton General Hospital. Of 191 patients, 80 underwent opioid rotati on (OR) for cognitive failure, hallucinations, myoclonus, nausea and v omiting, local toxicity, and persistent pain. These leading symptoms i mproved in 58/80 patients (73%, P < 0.01). Pain control, as measured o n a 10-cm visual analogue scale (VAS) improved from 4.4 +/- 2.3 to 3.6 +/- 2.0 (P < 0.004) at a dose significantly lower than that predicted to be equianalgesic (577 +/- 1535 mg before OR versus 336 +/- 593 mg after OR, P < 0.04). We conclude that symptoms of opioid toxicity can be relieved by OR, and that a choice of two or three different opioids is necessary to obtain satisfactory long-term pain control.