Which opioids should be avoided in renal impairment?
Morphine especially should be avoided in the setting of renal impairment. This is because about 75% of morphine is metabolized to morphine-3-glucuronide, which is inactive in the sense that it does not act on the mu receptor; however, it may be neurotoxic. Neurotoxic effects such as myoclonus have been documented. Also of concern is the morphine-6-glucuronide, which is a more potent mu-agonist than parent morphine. Elimination of morphine and its metabolites is primarily through renal excretion, and thus the issues of neurotoxicity with M3G and overdose with M6G are of concern in this special population. Meperidine also has a neurotoxic metabolite, normeperidine, which is known for causing seizures, and of important note, normeperidine is also renally cleared. For these reasons, morphine and meperidine should always be avoided in patients with renal insufficiency, particularly dialysis patients and geriatric patients. In clinical practice, meperidine is rarely used for pain, regardless of renal function, as much safer options are readily available.