Opioids to Treat Chronic Pain in the Older Adult: A Clinical Consensus to Guarantee Safety and Avoid Adverse Events

Pain management in older adults presents unique challenges owing to age-related physiological changes, comorbidities, polypharmacy, and heightened vulnerability to opioid-related adverse effects. This consensus review synthesizes current evidence and expert opinion on the safe and effective use of opioids in older adult patients. A multidisciplinary panel reviewed the literature, addressing the mechanisms of action of opioids, pharmacokinetic characteristics, routes of administration, pharmacology of aging, and distinctions in opioid use for cancer pain versus noncancer pain. Recommendations were developed through iterative consensus. Opioids produce analgesia primarily via μ, κ, δ opioid receptor agonism and nonclassical nociception. The receptor selectivity influences efficacy and side effect profiles. Age-related alterations, such as reduced renal and hepatic clearance, decreased lean body mass, increased body fat, and changes in protein binding, affect absorption, distribution, metabolism, and elimination, requiring dose adjustments and extended dosing intervals. The choice of route of administration (oral, transdermal, parenteral, epidural) should be based on initial needs, adherence to treatment, gastrointestinal function, and skin integrity. In older adult patients, opioid selection should be carefully considered, giving preference to agents with inactive metabolites or predictable clearance, and with conservative initial doses ("start low, go slow"), regular reassessment and proactive management of side effects, such as constipation, cognitive effects, and fall risk, are essential. For cancer pain, prioritizing potent opioids with transdermal administration for fixed-dose medication and ultrarapid acting fentanyl in pro re nata for the control of sudden pain is usually appropriate. Nevertheless, the target is the multimodal pharmacological treatment; for chronic noncancer pain, greater emphasis on therapy directed at the pathophysiology of pain, risk-benefit assessment, and time-limited use of opioids are strategic actions. Individualized opioid prescriptions in older adults, guided by pharmacologic principles, route-specific considerations, and differentiated approaches for cancer pain versus noncancer pain, optimize analgesia while minimizing harm. Further research should target age-specific dosing algorithms and long-term outcomes.