Narcotic drugs effective for severe, chronic pain in older patients

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Narcotic drugs effective for severe, chronic pain in older patients

20 May 2005 Medical News Today

Narcotic medications can safely and effectively ease severe, chronic

pain in older people with little risk that these patients will seek

ever-increasing doses, UCSF medical scientists have found. Younger

patients, however, are likely to want to rapidly increase their

medication dose, the researchers found, posing serious potential

health consequences.

The study is the first to systematically compare younger versus older

patients' desires/needs to escalate the dose of opioid pain

medications they take -- a class of drugs including morphine,

methadone and oxycodone (sold as OxyContin, Percocet among others).

Based on the new findings, the researchers suggest that the drugs may

be under-prescribed for older patients, yet pose unique risks for

younger patients.

Opioids have long been used for unremitting pain caused by nerve

damage, arthritis and other diseases, but clinicians and patients

often worry that use of the drugs will lead to patient requests for

ever-increasing doses. Extended opioid use at high doses can alter

immune and hormonal function and, ironically, increase pain

sensitivity. The escalating drug need, stemming from " tolerance " to a

given dose, also can become very costly.

The new findings show that patients 60 or older faced a much lower

risk of opioid " dose escalation " than did younger patients. Older

patients also received long-term pain relief from the opioids whereas

younger patients showed no long-term benefit.

The discovery about opioid tolerance and age was uncovered from a

study of patient records, and confirmed in animal studies. The

findings are being published in two papers in the June issue of

Anesthesia and Analgesia.

" We have found that older patients, often discouraged from using

opioids for pain management, actually gain significant long-term

relief with minimal risk of excessive dose escalation or toxicity, "

said Pamela Palmer, MD, PhD, professor of anesthesia at UCSF and

senior author of the two papers. Palmer is director of the UCSF Pain

Management Center.

In addition, long-term use of opioids at moderate levels does not

pose an increased risk for cardiac or kidney damage or gastric

ulcers, as some -2 inhibitors do -- a risk of greater concern for

older patients than younger ones, Palmer said. Sedation and

constipation are the main opioid side effects, but these can be

managed by modifying the selection of the opioid, the dosage and

proper bowel medications.

Researchers examined the medical records of 206 patients who had been

treated for two years for severe, non-cancer-related pain, either

from nerve damage (called neuropathic pain) or from arthritis,

fibromyalgia and related conditions that cause what is known as

nociceptive pain. Patients were divided into younger (less than 50

years old) and older (over 60) age groups.

The records showed that both groups started with similar doses of

morphine-like drugs and both took about 14 to 15 months to reach

their peak dose. But the average peak dose of the younger group was

more than twice that of the older group. In many cases, peak doses

for younger patients were well over half a gram per day of morphine

or related opioid.

Younger patients with nociceptive pain escalated the drug dosage at

a " tremendous rate " for more than a year, the researchers report. Yet

they did not achieve any long-term pain relief from these high doses

according to standard self-assessment scores. In contrast, the older

patients, with less than half the dose escalation, reported

significant relief from pain, the scientists found.

The researchers speculate that the difference between the older and

younger patients may be the result of molecular changes in neurons

that occur with aging, and they cite this as a particularly important

area for future research. They also recognize the importance of a

prospective study rather than a retrospective one, and they are

planning a follow-up study.

In an animal study, the scientists sought to confirm the age-related

difference in tolerance to opioid drugs. They note that no study had

systematically evaluated how quickly rats develop tolerance to opioid

pain medication as a function of age. Rats aged three weeks, three

months, six months and a year were given twice-daily injections of

morphine proportional to their weight, and pain-relief was assessed

in a standard procedure of applying heat to the rat's tail and

measuring how quickly the animal flicked its tail away from the heat

source.

The researchers found that the youngest rats experienced drug

tolerance more than five times sooner than the oldest rats. Six-month-

old and three-month-old rats showed a 250 percent and a 150 percent

increase in time to tolerance compared with the three-week-old rats,

they reported. The findings are consistent with the human studies in

which older patients continue to experience benefit from a given

opioid dosage while younger patients need to escalate the dosage.

Why the older patients found long-lasting pain relief at lower doses -

- a finding confirmed in the animal studies -- is not certain, Palmer

says. But the results suggest to the UCSF scientists that use of

opioids for pain relief in both the young and the old should be

reconsidered.

For older patients, opioids appear to be a safe, effective medication

to treat long-lasting, serious pain without the increased risks posed

by -2 inhibitors and other anti-inflammatory drugs, Palmer

concludes. On the other hand, younger people should be cautious of

using daily opioids to treat chronic pain.

" Younger people are more vulnerable to opioid tolerance and ever-

escalating doses, and they are at much lower risk than older patients

for heart attack and gastrointestinal bleeding linked to anti-

inflammatory drugs, " she said. In sum, younger patients may be better

candidates for the newer non-steroidal anti-inflammatories and poorer

candidates for opioids, while older patients might benefit more from

opioids but are at greater risk for serious side effects from anti-

inflammatory drugs, Palmer says.

Lead author on the retrospective patient pain study is Chante Buntin-

Mushock, MD, research fellow in the UCSF neurology and anesthesia

departments. Co-authors are , MD, and Kumi Moriyama, MD,

both in the anesthesia department at UCSF.

The research is supported in part by the U.S. Public Health Service.

Lead author on the animal study is Yan Wang, MD, postdoctoral fellow

in anesthesia at UCSF. Co-authors are , MD; Kumi

Moriyama, MD; Ki-jun Kim, MD, PhD; Manhoar Sharma, PhD; and Guo-xi

Xie, MD, PhD, all in the UCSF anesthesia department.

Support comes from the National Institutes of Health.

University of California - San Francisco

http://www.ucsf.edu