Clinical Approaches to Special Issues Related to Opioid Therapy

Definition, diagnosis and treatment strategies for opioid-induced bowel dysfunction–Recommendations of the Nordic Working Group

Background and aims

Opioid-induced bowel dysfunction (OIBD) is an increasing problem due to the common use of opioids for pain worldwide. It manifests with different symptoms, such as dry mouth, gastro-oesophageal reflux, vomiting, bloating, abdominal pain, anorexia, hard stools, constipation and incomplete evacuation. Opioid-induced constipation (OIC) is one of its many symptoms and probably the most prevalent. The current review describes the pathophysiology, clinical implications and treatment of OIBD.

Methods

The Nordic Working Group was formed to provide input for Scandinavian specialists in multiple, relevant areas. Seven main topics with associated statements were defined. The working plan provided a structured format for systematic reviews and included instructions on how to evaluate the level of evidence according to the GRADE guidelines. The quality of evidence supporting the different statements was rated as high, moderate or low. At a second meeting, the group discussed and voted on each section with recommendations (weak and strong) for the statements.

Results

The literature review supported the fact that opioid receptors are expressed throughout the gastrointestinal tract. When blocked by exogenous opioids, there are changes in motility, secretion and absorption of fluids, and sphincter function that are reflected in clinical symptoms. The group supported a recent consensus statement for OIC, which takes into account the change in bowel habits for at least one week rather than focusing on the frequency of bowel movements. Many patients with pain receive opioid therapy and concomitant constipation is associated with increased morbidity and utilization of healthcare resources. Opioid treatment for acute postoperative pain will prolong the postoperative ileus and should also be considered in this context. There are no available tools to assess OIBD, but many rating scales have been developed to assess constipation, and a few specifically address OIC. A clinical treatment strategy for OIBD/OIC was proposed and presented in a flowchart. First-line treatment of OIC is conventional laxatives, lifestyle changes, tapering the opioid dosage and alternative analgesics. Whilst opioid rotation may also improve symptoms, these remain unalleviated in a substantial proportion of patients. Should conventional treatment fail, mechanism-based treatment with opioid antagonists should be considered, and they show advantages over laxatives. It should not be overlooked that many reasons for constipation other than OIBD exist, which should be taken into consideration in the individual patient.

Conclusion and implications

It is the belief of this Nordic Working Group that increased awareness of adverse effects and OIBD, particularly OIC, will lead to better pain treatment in patients on opioid therapy. Subsequently, optimised therapy will improve quality of life and, from a socio-economic perspective, may also reduce costs associated with hospitalisation, sick leave and early retirement in these patients.

Opioid rotation in clinical practice

INTRODUCTION

Although chronic opioid therapy is usually initiated using short-acting opioids, many patients with chronic pain are subsequently converted to long-acting and extended-release preparations. In clinical practice, optimal management requires careful individualization of dosage in order to achieve an appropriate balance of efficacy and adverse effects. After successful initiation and stabilization of opioid treatment, subsequent changes in regimen may still be required to maintain efficacy with an acceptable adverse effect profile.

METHODS

This is a qualitative review of the available literature from June 2012 or earlier on opioid rotation for the management of chronic pain in the clinical setting. The PubMed database was searched using various search terms, and additional articles were identified through manual search of the bibliographies of articles identified through the PubMed search. Papers were selected based on relevance to the topic.

RESULTS

When considering opioid rotation, clinicians must take into account not only the significant differences in potency among opioid drugs but also the considerable interpatient variability in response to opioids. The estimate of relative potency used in calculating an appropriate starting dose when switching from one opioid to another has been codified on equianalgesic dose tables. To reduce the risk of unintentional overdose, a two-step calculation has been proposed, which incorporates an initial reduction (typically 25-50%) in the equianalgesic dose followed by a second evaluation based on the severity of pain at the time of rotation along with other medical or psychosocial factors that might alter the effectiveness and tolerability of the new drug. Given the uncertainty of accurately predicting a patient's response to treatment, each initial exposure to a new opioid should be considered a discrete clinical trial to assess the degree of response. Systematic reviews of opioid rotation have documented the re-establishment of adequate pain control or reduced adverse effects in 50-80% of patients.

CONCLUSIONS

Although continued research is needed to refine equianalgesic doses further, opioid rotation is an important and necessary practice in patients with chronic cancer or noncancer pain that is refractory to the initially used opioid.

Use of opioids in long-term management of temporomandibular joint dysfunction

The long-term treatment of patients with chronic temporomandibular joint dysfunction has been challenging. The long-term use of opioids in these patients can be neither supported nor refuted based on current evidence. However, evidence is available to support the long-term use of opioids in other chronic noncancer pain states with reduced pain, improved function, and improved quality of life. One group of patients with chronic temporomandibular joint pain, for whom both noninvasive and invasive treatment has failed, might benefit from long-term opioid medication. The choices include morphine, fentanyl, oxycodone, tramadol, hydrocodone, and methadone. Adjunct medication, including antidepressant and anticonvulsant drugs, can also be used. The safety of these medications has been well established, but the potential for adverse drug-related behavior does exist, requiring appropriate patient selection, adequate monitoring, and intervention when needed.