Opioid Analgesics for Persistent Pain in the Older Patient

Abstract

Naturally occurring opioids have been used as analgesics for thousands of years. From these, semisynthetic and synthetic derivatives have emerged in the search for the ‘perfect’ opioid analgesic, without success. Weak opioid analgesics include codeine and propoxyphene, intermediate-strength opioid analgesics include the agonist-antagonists (e.g., pentazocine and butorphanol) and the partial agonist buprenorphine and the strong opioid analgesics include morphine, oxycodone, oxymorphone, hydrocodone, hydromorphone, fentanyl and meperidine. Propoxyphene, meperidine, agonist-antagonists and partial agonists should be avoided in most elderly patients owing to their unfavorable risk–benefit profiles. The other opioids can be recommended for use in the elderly and appear to be interchangeable (in equianalgesic doses) based upon similar efficacy and tolerability profiles. The aging process alters the pharmacokinetics of nearly all opioid analgesics, mainly due to alternations in the activity of excretory pathways (liver and kidneys). The need for frequent dosing of these drugs, due to their short terminal disposition half-lives, can be largely overcome by using oral or transdermal extended-release formulations that allow dosing as infrequently as every 3 days. Opioid side effects can be anticipated and, in virtually all cases, either tolerance develops or pre-emptive therapy can prevent the emergence of or minimize the impact of the side effect (e.g., laxative therapy prevents constipation). Opioid analgesics are effective for virtually all types of pain, including neuropathic pain (where chronic opioid therapy works, while ‘as-needed’ therapy does not). This review summarizes the evidence for and against the use of individual opioid analgesics in the elderly. This, in turn, should promote the safe and effective use of the preferred opioid analgesics in this patient population.