Table 3.

Opioid considerations in older adults

Opioid	Older adult considerations
Morphine	Potential for accumulation of M3G and M6G in patients with renal compromise Consider lowering the dose of morphine or choosing an alternative opioid in patients with renal insufficiency
Oxycodone	Metabolism mediated by the CYP450 enzyme, but clinical implications are unclear Consider
Hydromorphone	Two active metabolites exist, H3G and H6G, although the impact of these metabolites is unclear Approximately 6x more potent intravenously than morphine so caution should be used with dosing Lack of CYP450 metabolism can be an advantage for older patients
Fentanyl	Highly lipophilic and onset dependent on route of administration Metabolized by CYP450 but implications unclear Transdermal route  Potential for a delayed onset and rate of elimination in patients with higher amounts of adipose tissue  Should not be used in patients with cachexia who lack sufficient body fat  Best to use for stable pain as it is more difficult to titrate than oral opioids  Ease of administration of one patch every 3 days may be an advantage for older adults Transmucosal fentanyl is easily absorbed through the oral mucous membranes resulting in a rapid onset for breakthrough pain episodes
Methadone	Highly protein bound resulting in an extended half-life which can lead to drug accumulation and oversedation QTc prolongation, especially in higher doses >100 mg/day Drug-drug interactions are common, especially in older adults who are often prescribed multiple medications

M3G: Morphine-3-glucuronide, M6G: Morphine-6-glucuronide, H3G: Hydromorphone-3-glucuronide, H6G: Hydromorphone-6-glucuronide