Chronic Pain Management with Opioid Analgesics: A Pharmacist Perspective
Michelle M. Zingone, PharmD, BCPS*
The field of pain management has undergone considerable change over the past 15 years. With the recognition that chronic pain is not a single entity, but rather a heterogeneous condition with a myriad of causes and perpetuating factors, the treatment approach is no longer empiric. Current recommendations call for more specific treatments (depending on the pain mechanism) and a comprehensive strategy involving behavioral approaches and a combination of medications (eg, nonsteroidal anti-inflammatory drugs, antidepressants, opioids, antiepileptic agents, local anesthetic agents, and skeletal muscle relaxants).
For many patients living with chronic pain, opioids remain the cornerstone of analgesia, bringing a degree of relief and a return of function. Diligent use of these potent analgesics, at appropriate doses in carefully selected patients, may have a tremendous impact on uncontrolled chronic pain and its many consequences (eg, anxiety, depression, and insomnia). However, several clinical and social challenges complicate opioid use in chronic pain management. Long-term use of opioids is associated with an adverse effect profile that is unique, in comparison to the short-term opioid side effects that clinicians have become accustomed to. Also, chronic opioid therapy remains controversial, mainly because clinicians often fear regulatory scrutiny and patient dependency or abuse. With the media often stigmatizing opioid use and mislabeling patients with chronic pain as addicts, patients often share these fears. However, with the recognition that most patients treated with opioids for chronic pain do not become addicted, a transformation in thinking has begun. It is necessary for providers to differentiate between physical dependence, addiction, and pseudoaddiction when caring for patients with chronic pain.
Because pharmacists in the community setting very commonly encounter patients in various states of chronic pain and are in regular contact with prescribing physicians, they can have a significant impact on treatment outcomes in these patients. However, in providing effective patient counseling and accurate physician recommendations, it is imperative for pharmacists to have a firm understanding of current and emerging opioid-related challenges, in addition to the basic principles of opioid administration and equianalgesic conversions.
This issue of University of Tennessee Advanced Studies in Pharmacy is dedicated to educating pharmacists on the evolving role of opioids in the management of chronic pain. Lynn Webster, MD, FACPM, FASAM, offers a review of currently available opioid formulations and the major principles governing their use. Dr Webster focuses on the use of long-acting agents or controlled-release/sustained-release (SR) preparations for general treatment of chronic persistent pain because they provide more consistent, around-the-clock pain relief. Immediate-release preparations with a short half-life should ideally be used as supplemental agents for breakthrough pain that may occur between doses of SR agents and for incident (activity-related) pain. Dr Webster also explores emerging evidence relating to the long-term effects of chronic opioid therapy on the neuroendocrine system (immune, endocrine, and nervous systems). By disrupting this organ system, opioids may ultimately cause various endocrinopathies (eg, hypo-gonadism, hypothyroidism, and hormone deficiencies), immune dysfunction, and central nervous system changes (eg, sleep apnea). Based on his experience and expertise in avoiding/minimizing opioid abuse, Dr Webster offers ample, evidence-based advice on assessing individual risk of opioid abuse and structuring therapy and monitoring based on that risk. A review of abuse-resistant opioids that are currently in the pipeline is also provided.
Ewan McNicol, RPh, MS, centers his discussion on administration issues, side effect management, and equianalgesic conversions pertaining to current opioid therapy. In reviewing the available routes of opioid administration, Mr McNicol noted that alternative routes (eg, transdermal, rectal, vaginal, and topical) are usually used in patients with certain physiologic limitations, such as mucositis-related dysphagia, chemotherapy-induced nausea, malabsorption from gastrointestinal dysfunction (eg, fistula and dumping syndrome in human immunodeficiency virus/acquired immune deficiency syndrome), or the need to swallow an impractical number of tablets. Mr McNicol also offers special considerations pertaining to common equianalgesic conversions (eg, oral morphine to fentanyl patch), pointing out that patients may vary in their response to a certain opioid and they may require higher or lower conversion factors than those suggested. Mr McNicol supplements his section on equianalgesic conversion by including a case study of a patient who presents to a community pharmacy with postherpetic neuralgia and requires multiple equianalgesic conversions throughout his course of opioid therapy. In concluding his discussion, Mr McNicol offers several considerations in effectively counseling patients on opioids and participates in a brief interview relating to the challenges of communicating with patients suffering from chronic pain.
As the baby boomer population continues to age, the incidence of people suffering from chronic pain is expected to increase. Currently, more than 50 million Americans (9.5 million of whom are ≥60 years) suffer from chronic pain and, based on a survey indicating that 40% of those with chronic pain are unable to find adequate pain relief, there is certainly a need and opportunity to improve pain management.1,2
1. American Pain Foundation. Fast Facts About Pain. Available at: http://www.painfoundation.org/page.asp?file=library/fastfacts.htm. Accessed January 3, 2008.
2. American Academy of Pain Medicine, American Pain Society, Janssen Pharmaceutica. Chronic pain in America survey. Available at: http://www.ampainsoc.org/links/roadblocks/conclude_road.htm. Accessed February 12, 2008.
*Assistant Professor, University of Tennessee College of Pharmacy, Knoxville, Tennessee.
Address correspondence to: Michelle M. Zingone, PharmD, BCPS, Assistant Professor, University of Tennessee College of Pharmacy, 1924 Alcoa Highway, Box 117, Knoxville, TN 37920. E-mail: firstname.lastname@example.org.
The content in this monograph was developed with the assistance of a staff medical writer. Each author had final approval of his/her article and all its contents.