Opioids for persistent pain in older adults

OPIOIDS

The American Geriatrics Society, American Pain Society, and American Academy of Pain Medicine made recommendations in 2009 supporting the use of opioids to treat persistent pain in patients who are carefully selected and monitored.^4,6 An international expert panel in 2008 issued a consensus statement²⁷ of evidence that also supported the use of opioids for those over age 65. The Federation of State Medical Boards of the United States also supports the use of opioids, particularly for adults who have refractory pain, and it recognizes undertreatment of pain as a public health issue.²⁸

Clinicians are most comfortable with using opioids to manage cancer pain, but these drugs also provide an acceptable and effective means of analgesia in nonmalignant, persistent pain syndromes.²⁴ The American Geriatrics Society Panel on Pharmacological Management of Persistent Pain in Older Persons recommends treatment with opioids in all patients with moderate-to-severe pain, pain-related functional impairment, or decreased quality of life due to pain, even though the evidence base is not robust.³

Unlike NSAIDs and acetaminophen, opioids do not have a presumed ceiling effect. However, in patients ages 15 to 64, the greatest benefits have been observed at lower doses of opioids, and the risk of death increases with dose.²⁹ The dose can be raised gradually until pain is relieved.

Start low and go slow

When starting opioid therapy:

• Choose a short-acting agent
• Give it on a trial basis
• Start at a low dose and titrate up slowly.

No data are available to tell us how much to give an older adult, but a reasonable starting dose is 30% to 50% of the recommended dose for a younger adult.²⁴ Short-acting opioids should be titrated by increasing the total daily dose by 25% to 50% every 24 hours until adequate analgesia is reached.²⁴

Older adults who have frequent or continuous pain should receive scheduled (around-the-clock) dosing in an effort to achieve a steady state.³ The half-lives of opioids may be longer in older adults who have renal or hepatic insufficiency; therefore, their doses should be lower and the intervals between doses longer.²⁷

When long-acting opioid preparations are used, it is important to also prescribe breakthrough (short-acting) pain management.² Breakthrough pain includes end-of-dose failure, incident pain (ie, due to an identifiable cause, such as movement), and spontaneous pain; these can be prevented or treated with short-acting, immediate-release opioid formulations.³

Once therapy is initiated, its safety and efficacy should be continually monitored.² With long-term use, patients should be reassessed for ongoing attainment of therapeutic goals, adverse effects, and safe and responsible medication use.³

Table 3 lists common opioids and their initial dosing.

SIDE EFFECTS

Constipation

This is one of the most common side effects of opioids,³⁰ and although many opioid side effects wane within days of starting as tolerance develops, this one does not.

A bowel regimen should be initiated when starting any opioid regimen. Although most of the evidence for bowel regimens is anecdotal, increasing fluid and fiber intake and taking stool softeners and laxatives are effective.­³¹

For very difficult cases of opioid constipation, randomized trials suggest that specific agents with opioid antagonist activity that specifically target the gastrointestinal system can help.^32,33 Opioid antagonists are not used as routine prophylaxis, but rather for constipation that is refractory to laxatives.^34,35 A meta-analysis demonstrated that methylnaltrexone, naloxone, and alvimopan were generally well tolerated, with no significant difference in adverse effects compared with placebo.³⁶