Chronic opioid therapy for non-cancer pain

Prevention, diagnosis, and treatment of opioid use disorder under the supervision of opioid stewardship programs: it's time to act now

The third opium war may have already started, not only due to illicit opioid trafficking from the Golden Crescent and Golden Triangle on the international front but also through indiscriminate opioid prescription and opioid diversion at home. Opioid use disorder (OUD), among unintentional injuries, has become one of the top 4 causes of death in the United States (U.S.). An OUD is defined as a problematic pattern of opioid use resulting in clinically significant impairment or distress, consisting of 2 or more of 11 problems within 1 year, as described by the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition. Observation of aberrant behaviors of OUD is also helpful for overworked clinicians. For the prevention of OUD, the Opioid Risk Tool and the Current Opioid Misuse Measure are appropriate screening tests before and during opioid administration, respectively. Treatment of OUD consists of 3 opioid-based U.S. Food and Drug Administration-approved medications, including methadone, buprenorphine, and naltrexone, and non-opioid-based symptomatic medications for reducing opioid withdrawal syndromes, such as α2 agonists, β-blockers, antidiarrheals, antiemetics, non-steroidal anti-inflammatory drugs, and benzodiazepines. There are at least 6 recommendable guidelines and essential terms related to OUD. Opioid stewardship programs are now critical to promoting appropriate use of opioid medications, improving patient outcomes, and reducing misuse of opioids, influenced by the successful implementation of antimicrobial stewardship programs. Despite the lack of previous motivation, now is the critical time for trying to reduce the risk of OUD.

Tramadol Biological Effects: 4: Effective Therapeutic Efficacy of Lagenaria siceraria Preparation (Gamal & Aref1) and Melatonin on Cell Biological, Histochemical, and Histopathological Changes in the Kidney of Tramadol-Induced Male Mice

Tramadol is used worldwide and is listed in many medical guidelines to treat both acute and chronic pains. There is a growing evidence of abuse of tramadol in some African and West Asian countries. Tramadol has some side effects. The present study designed to follow up the treatment of the cellular responses which might be induced in the kidney of tramadol mice. Treated mice received daily injection of tramadol dose (125 μg/100 g b.wt) for 20 and 40 days. Other mice received tramadol for 40 days and then were divided into three groups: the first received distilled water, the second received Lagenaria siceraria, and the third received melatonin daily for 40 days. Both the daily injection of tramadol for 20 and 40 days resulted in radical, extensive, and severe alterations in the normal histological architecture of the kidney. Treatment with Lagenaria siceraria or melatonin after tramadol administration for a long-term, markedly changed the collagen content and other chemical components, that may reach nearly normal levels. Such findings propose that although tramadol has many cytological and histopathological side effects on the kidneys of male mice, the treatments via Lagenaria siceraria and melatonin have effective therapeutic impacts on the tramadol side effects.

Blood lead concentration among oral/inhaled opium users: systematic review and meta-analysis

Lead is a poisonous heavy metal with various known side effects. The effect of opium on raising blood lead concentration (BLC) has been investigated with no general agreement. In Iran, the number of lead poisoning cases has raised among the opium-addicted population. This systematic review and meta-analysis aim to combine the results of previous studies with the Iranian population to investigate the effect of opium on BLC. In this systematic review, PubMed/Medline, Web of Sciences, Embase, and Scopus were searched for studies using the Iranian population to compare the BLC of opium-addicted cases and non-addicted controls till January 2020. A random-effects model was used to pool the results. I-square test was used to assess the heterogeneity of the studies. The effect sizes were standardized mean differences (proxied by Hedges' g) followed by a 95% confidence interval. Of 417 initial articles, 13 studies met the inclusion criteria to be considered in the meta-analysis. The sample size of eligible studies ranged from 40 to 131 (mean 81.83, SD 27.6). All studies were focused on adults with mean age ranged from 33.5 to 65.15 years old (overall mean 49.0, SD 7.66). There were 13 studies included with 18 Hedges' g effect sizes. Using a random effect model, the pooled effect size was g_w = 2.48 (95% CI: 1.58-3.39) and statistically significant in favor of opium-addicted participants. Moreover, heterogeneity was 96.6% (I2=96.6, Q(17) = 504.95, p < 0.001). For studies with large Hedges' g effect sizes (> 4) identified as outliers and removed from meta-analysis. The pooled Hedges' g effect size reduced to 1.39 (95% CI: 0.94-1.85), still highly significant in favor of higher levels of lead in the opium-addicted group. The funnel plot appeared symmetrical confirmed by Egger's test (t = 1.87, p = 0.088), indicating no publication bias present.

Managing Chronic Non-Malignant Pain in the Elderly: Intrathecal Therapy

Intrathecal drug delivery (IDD) was first described in 1981 by Onofrio, who used a pump for continuous and intrathecal delivery of morphine to treat cancer pain. Over the following four decades, many reports supported this treatment method with implanted pumps for cancer and non-cancer pain. To date, more than 300,000 pumps for pain therapy and spasticity have been implanted worldwide. This article reviews current knowledge regarding intrathecal opioid therapy, focusing particularly on the use of IDD in elderly patients. Current literature is presented, and the arguments in favor of and against this therapy in elderly patients are discussed.

Comparison between intravenous morphine versus fentanyl in acute pain relief in drug abusers with acute limb traumatic injury

BACKGROUND

Rapid and effective pain relief in acute traumatic limb injuries (ATLI) is one of the most important roles of emergency physicians. In these situations, opioid addiction is an important concern because of the dependency on opioids. The study aims to compare the effectiveness of intravenous (IV) fentanyl versus morphine in reducing pain in patients with opioid addiction who suffered from ATLI.

METHODS

In this double-blind randomized clinical trial, 307 patients with ATLI, who presented to the emergency department (ED) from February 2016 to April 2016, were randomly divided into two groups. One group (152 patients) received 0.1 mg/kg IV morphine. The other group (155 patients) received 1 mcg/kg IV fentanyl. Patients' demographic data, pain score at specific intervals, vital signs, side effects, satisfaction and the need for rescue analgesia were recorded.

RESULTS

Eight patients in the morphine group and five patients in the fentanyl group were excluded. Pain score in the fentanyl group had a significant decrease at 5-minute follow-up (P value=0.00). However, at 10, 30, and 60-minute follow-ups no significant differences were observed between the two groups in terms of pain score reduction. The rescue analgesia was required in 12 (7.7%) patients in the fentanyl group and in 48 (31.6%) patients in the morphine group (P value=0.00). No significant difference was observed regarding side effects, vital signs and patients' satisfaction between the two groups.

CONCLUSION

Fentanyl might be an effective and safe drug in opioid addicts suffering from ATLI.

Treatment for chronic low back pain: the focus should change to multimodal management that reflects the underlying pain mechanisms

Chronic low back pain: Chronic pain is the most common cause for people to utilize healthcare resources and has a considerable impact upon patients' lives. The most prevalent chronic pain condition is chronic low back pain (CLBP). CLBP may be nociceptive or neuropathic, or may incorporate both components. The presence of a neuropathic component is associated with more intense pain of longer duration, and a higher prevalence of co-morbidities. However, many physicians' knowledge of chronic pain mechanisms is currently limited and there are no universally accepted treatment guidelines, so the condition is not particularly well managed.

DIAGNOSIS

Diagnosis should begin with a focused medical history and physical examination, to exclude serious spinal pathology that may require evaluation by an appropriate specialist. Most patients have non-specific CLBP, which cannot be attributed to a particular cause. It is important to try and establish whether a neuropathic component is present, by combining the findings of physical and neurological examinations with the patient's history. This may prove difficult, however, even when using screening instruments. Multimodal management: The multifactorial nature of CLBP indicates that the most logical treatment approach is multimodal: i.e. integrated multidisciplinary therapy with co-ordinated somatic and psychotherapeutic elements. As both nociceptive and neuropathic components may be present, combining analgesic agents with different mechanisms of action is a rational treatment modality. Individually tailored combination therapy can improve analgesia whilst reducing the doses of constituent agents, thereby lessening the incidence of side effects.

CONCLUSIONS

This paper outlines the development of CLBP and the underlying mechanisms involved, as well as providing information on diagnosis and the use of a wide range of pharmaceutical agents in managing the condition (including NSAIDs, COX-2 inhibitors, tricyclic antidepressants, opioids and anticonvulsants), supplemented by appropriate non-pharmacological measures such as exercise programs, manual therapies, behavioral therapies, interventional pain management and traction. Surgery may be appropriate in carefully selected patients.

Validation of the Pain Resilience Scale in a Chronic Pain Sample

Psychosocial factors that protect against negative outcomes for individuals with chronic pain have received increased attention in recent years. Pain resilience, or the ability to maintain behavioral engagement and regulate emotions as well as cognitions despite prolonged or intense pain, is one such factor. A measure of pain-specific resilience, the Pain Resilience Scale, was previously identified as a better predictor of acute pain tolerance than general resilience. The present study sought to validate this measure in a chronic pain sample, while also furthering understanding of the role of pain resilience compared with other protective factors. Participants with chronic pain completed online questionnaires to assess factors related to positive pain outcomes, pain vulnerability, pain intensity, and quality of life. A confirmatory factor analysis confirmed the 2-factor structure of the Pain Resilience Scale previously observed among respondents without chronic pain, although one item from each subscale was dropped in the final version. For this chronic pain sample, structural equation modeling showed that pain resilience contributes unique variance to a model including pain acceptance and pain self-efficacy in predicting quality of life and pain intensity. Further, pain resilience was a better fit in this model than general resilience, strengthening the argument for assessing pain resilience over general resilience.

PERSPECTIVE

A modified version of the Pain Resilience Scale retained the original factor structure when tested in a chronic pain sample. Construct validity was supported by expected relationships with pain-related protective and vulnerability measures. Further, a model including positive pain constructs showed that pain resilience accounts for unique variability when predicting quality of life and pain intensity.

Basic Opioid Pharmacology

Opioids can be classified according to their mode of synthesis into alkaloids, semi-synthetic and synthetic compounds.There are three classical receptors (DOP, KOP and MOP). The novel NOP receptor is considered to be a non-opioid branch of the opioid receptor family.Opioids can either act as agonists, antagonists or partial agonists at these receptors.Opioid agonists bind to G-protein coupled receptors to cause cellular hyperpolarisation.MOP receptor agonists act in the central and peripheral nervous system to elicit analgesia.

An exploration of opioid medication management for non-malignant pain in primary care

The present study aimed to explore how prescription of opioid medication for chronic non-malignant pain (CNMP) is managed in primary care. We used audit as a research tool, and one general practitioner (GP) practice in West London acted as an exemplar. Of the practice population with CNMP, 1% had repeat prescription of at least 12 months duration for opioid analgesics at the time of data collection. These 1% are on highly controlled opioids. Our study showed the following: (1) long-term opioid prescription appears to follow a fluctuating course as opposed to staying the same; (2) we found that medication reviews were done in most cases (85.7%), but the quality of the process is difficult to assess and ascertain; and (3) we identified two incidences where opioid contract was implemented. In both cases, contracts were used as a last chance warning for patients who were already problematic, suggesting that opioid contracts served as a disciplinary tool rather than a preventative measure. Our findings highlight a need for a more structured and specific review of analgesic medication, and a need for a simple and effective way to identify patients at high risk of developing problematic use, to ensure better monitoring and early presentations.

Indicators of drug-seeking aberrant behaviours: the feasibility of use in observational post-marketing cohort studies for risk management

Background

Problematic prescription drug use is reflected by or associated with drug-seeking aberrant behaviours. Research gaps include lack of post-marketing evidence and instruments. As part of the pharmacovigilance requirements, a risk management plan was developed for fentanyl buccal tablets (FEBT) by the manufacturer, with an additional pharmacovigilance activity requested by the regulatory authority, to investigate the risks of misuse, abuse, criminal use, off-label use and accidental exposure to FEBT after the product became commercially available. A Modified Prescription-Event Monitoring (M-PEM), observational, post-authorisation safety surveillance (PASS) study was conducted, with an overall aim to examine the use of FEBT in relation to their safety as prescribed in primary care in England. One of the exploratory objectives included estimating the prevalence of aberrant behaviours during FEBT treatment.

Objective

To determine the feasibility of estimating the prevalence of risk factors associated with dependence on starting treatment and aberrant behaviours in patients during treatment with a prototypical abuse liable substance (fentanyl), as based on the application of an existing index (the Chabal criteria).

Methods

Data were collected as part of the M-PEM PASS study; exposure and outcome data (including risk factors for dependence and aberrant behaviours based on behavioural not clinical manifestations) were derived from questionnaires sent to primary care physicians in England during April 2008 to June 2011. For the exploratory objective of interest, descriptive statistics and simple (non-weighted) risk scores were constructed on aggregate counts (score ≥3 considered ‘high-risk’). Supplementary analyses explored the relationship between the two indices and the characteristics of patients with aberrant behaviours and those without (crude odds ratios plus 95 % confidence interval (CI) were calculated).

Results

In a cohort of 551 patients, the prevalence of at least one pre-existing risk factor for dependence was 26 % (n = 145), whilst the frequency of aberrant behaviours observed during treatment was 8 % (n = 46). Patients with aberrant behaviours had several different characteristics to patients without. The two indices were associated (χ² df (20) = 58.72, p < 0.001), but a high-dependence risk-factor score provided a poor indication of high aberrant behaviour risk; the area under the receiver operating characteristic curve was 0.58 (95 % CI 0.41, 0.74).

Limitations

Study limitations included subjectivity in relation to physicians identifying aberrant behaviours, and under-reporting thereof in PASS observational study designs. The presence of these criteria does not confirm misuse, but should be considered as a signal of problematic opioid misuse, which requires investigation. Further research is needed to develop a more robust analytical construct.

Conclusion

In this PASS study, the prevalence of at least one pre-existing risk factor for dependence was 26 %, whilst the frequency of aberrant behaviours observed during treatment was 8 %. Patients with aberrant behaviours had several different characteristics to patients without. This study demonstrates the feasibility of the systematic collection of physician reports of risk factors for dependence and aberrant behaviours to facilitate the development of risk scores, using these reports to support the post-marketing risk management of products with misuse potential.

A randomized, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy and safety of the extended-release tramadol hydrochloride/acetaminophen fixed-dose combination tablet for the treatment of chronic low back pain

BACKGROUND

Chronic low back pain is a common condition that is often difficult to treat. The combination of tramadol hydrochloride and acetaminophen in an extended-release formulation has been shown to provide rapid and long-lasting analgesic effects resulting from the synergistic activity of these 2 active ingredients.

OBJECTIVE

The goal of this study was to evaluate the efficacy and safety of extended-release tramadol hydrochloride 75-mg/acetaminophen 650-mg fixed-dose combination tablets (TA-ER) for the treatment of chronic low back pain.

METHODS

This Phase III, double-blind, placebo-controlled, parallel-group study enrolled 245 patients with moderate to severe (≥4 cm on a 10-cm visual analog scale) chronic (≥3 months') low back pain insufficiently controlled by previous NSAIDs or cyclooxygenase-2-selective inhibitors and randomly assigned them to receive 4 weeks of either TA-ER or placebo. The primary efficacy end point was the percentage of patients with a pain intensity change rate ≥30% from baseline to final evaluation. Secondary end points included quality of life (Korean Short Form-36), functionality (Korean Oswestry Disability Index), and adverse events.

RESULTS

The percentage of patients with a pain intensity change rate ≥30% was significantly higher (P < 0.05) in the TA-ER group than in the placebo group for both the full analysis set and the per-protocol population. Pain relief success rate from baseline was significantly higher with TA-ER versus placebo at days 8 and 15 but not at the final visit. Patients in the TA-ER group had significant improvements versus placebo in role-physical, general health, and reported health transition domains of the Korean Short Form-36 and significantly higher functional improvements in the personal care section of the Korean Oswestry Disability Index. Patient assessment of overall pain control as "very good" was also significantly higher with TA-ER than with placebo. Adverse events were reported more frequently with TA-ER than with placebo; the most common adverse events reported were nausea, dizziness, constipation, and vomiting.

CONCLUSIONS

TA-ER was significantly more effective than placebo in providing pain relief, functional improvements, and improved quality of life. It exhibited a predictable safety profile in patients with chronic low back pain. ClinicalTrials.gov identifier: NCT01112267.

Anesthesia for opioid addict: Challenges for perioperative physician

Opioid addiction is on a rise globally. Such a patient presents to an anesthesiologist as well as to the surgeon with an array of challenges. We present the case of an opioid addict (pentazocine) who presented for debridement and grafting of eschars and old healed scars. Initially he was medically managed for opioid addiction followed by a planned anesthesia. We hereby discuss the challenges faced during perioperative period.

Modeling the impact of simulated educational interventions on the use and abuse of pharmaceutical opioids in the United States: a report on initial efforts

Three educational interventions were simulated in a system dynamics model of the medical use, trafficking, and nonmedical use of pharmaceutical opioids. The study relied on secondary data obtained in the literature for the period of 1995 to 2008 as well as expert panel recommendations regarding model parameters and structure. The behavior of the resulting systems-level model was tested for fit against reference behavior data. After the base model was tested, logic to represent three educational interventions was added and the impact of each intervention on simulated overdose deaths was evaluated over a 7-year evaluation period, 2008 to 2015. Principal findings were that a prescriber education intervention not only reduced total overdose deaths in the model but also reduced the total number of persons who receive opioid analgesic therapy, medical user education not only reduced overdose deaths among medical users but also resulted in increased deaths from nonmedical use, and a "popularity" intervention sharply reduced overdose deaths among nonmedical users while having no effect on medical use. System dynamics modeling shows promise for evaluating potential interventions to ameliorate the adverse outcomes associated with the complex system surrounding the use of opioid analgesics to treat pain.

Barriers to pain management: focus on opioid therapy

Despite the availability of effective pain treatments, there are numerous barriers to effective management resulting in a large proportion of patients not achieving optimal pain control. Chronic pain is inadequately treated because of a combination of cultural, societal, educational, political and religious constraints. The consequences of inadequately treated pain are physiological and psychological effects on the patient, as well as socioeconomic implications. Unreasonable failure to treat pain is viewed as unethical and an infringement of basic human rights. The numerous barriers to the clinical management of pain vary depending on whether they are viewed from the standpoint of the patient, the physician, or the institution. Identification and acknowledgement of the barriers involved are the first steps to overcoming them. Successful initiatives to overcome patient, physician and institutional barriers need to be multifaceted in their approach. Multidisciplinary initiatives to improve pain management include dissemination of community-based information, education and awareness programmes to attempt to change attitudes towards pain treatment. A better awareness and insight into the problems caused by unrelieved pain and greater knowledge about the efficacy and tolerability of available pain management options should enable physicians to seek out and adhere to treatment guidelines, and participate in interventional and educational programmes designed to improve pain management, and for institutions to implement the initiatives required. Although much work is underway to identify and resolve the issues in pain management, many patients still receive inadequate treatment. Continued effort is required to overcome the known barriers to effective pain management.

Cost-effectiveness of tapentadol prolonged release compared with oxycodone controlled release in the UK in patients with severe non-malignant chronic pain who failed 1st line treatment with morphine

OBJECTIVES

The aim of this analysis was to assess the cost-effectiveness of tapentadol PR (prolonged release) compared with oxycodone CR (controlled release) in severe non-malignant chronic pain patients in whom controlled release morphine was ineffective or not tolerated.

METHODS

A Markov model was developed to assess costs and benefits over a 1-year time horizon from the National Health Service perspective in the UK. Patients could either continue on 2nd line therapy or switch to 3rd line opioid due to lack of efficacy or poor tolerability. Patients failing also 3rd line therapy entered the final absorbing health state (4th line). Data on tolerability, efficacy, and utilities for tapentadol and oxycodone were obtained from the three comparative phase III clinical trials. Costs of resource consumption associated with opioid treatment were derived from a retrospective database analysis of anonymized patient records.

RESULTS

The model results predicted that initiating 2nd line therapy with tapentadol leads to higher effectiveness and lower costs vs oxycodone. For the overall population included in the clinical trials, mean annual costs per patient when treated with tapentadol and oxycodone were £3543 and £3656, respectively. Treatment with tapentadol, while cheaper than oxycodone, was more effective (0.6371 vs 0.6237 quality-adjusted life years (QALYs) for tapentadol and oxycodone, respectively), meaning that tapentadol dominated oxycodone. For the sub-group of opioid-experienced patients with severe pain at baseline the ranking in terms of costs and QALYs remained unchanged. Extensive sensitivity analyses showed that conclusions about the cost-effectiveness are consistent.

CONCLUSIONS

The cost-effectiveness study suggested that initiating 2nd line treatment in patients with severe non-malignant chronic pain in the UK with tapentadol instead of oxycodone improves patients' quality-of-life and is less costly. Key limitations when interpreting the results are the use of different sources to populate the model and restricted generalizability due to data extrapolation.

System dynamics modeling as a potentially useful tool in analyzing mitigation strategies to reduce overdose deaths associated with pharmaceutical opioid treatment of chronic pain

OBJECTIVE

To illustrate a system-level, simulation-based approach for evaluating mitigation strategies to address the dramatic rise in abuse, addiction, and overdose deaths associated with the use of pharmaceutical opioid analgesics to treat chronic pain. SIMULATED INTERVENTIONS: Making available drug formulations with increased tamper-resistance, prescriber education programs, and programs that reduce rates of medical user-related abuse and addiction. SIMULATED OUTCOME MEASURE: Number of overdose deaths of medical users of pharmaceutical opioid analgesics, including those who abuse or have become addicted.

METHODS

A demonstration system dynamics model is developed, tested, and used to evaluate the impact of candidate mitigation strategies on the outcome measures.

RESULTS

Tamper-resistant drug products will likely reduce overdose death rates but may not reduce overall deaths if there is increased prescribing. Prescriber education would likely reduce deaths through a reduction in patient access to pharmaceutical opioid analgesics.

CONCLUSIONS

The system dynamics approach may have potential for opioid-related policy evaluation. However, metrics must be carefully selected, and trade-offs may be involved. For example, it may be difficult to limit negative outcomes associated with pharmaceutical opioids without adversely affecting chronic pain patients' access to pharmaceutical treatment. Ultimately, a combination of metrics and value judgments will be needed to properly evaluate mitigation strategies.

Epidemiology of chronic non-cancer pain in Europe: narrative review of prevalence, pain treatments and pain impact

BACKGROUND

Estimates on the epidemiology of chronic non-cancer pain vary widely throughout Europe. It is unclear whether this variation reflects true population differences or methodological factors. Such epidemiological information supports European decision makers in allocating healthcare resources.

OBJECTIVE

Pan-Europe epidemiological data about chronic non-cancer pain was obtained using systematic review principles in searching and summarising results.

METHODS

Multiple databases (MEDLINE, EMBASE, Cochrane Library, CRD Databases, and GIN) were systematically searched for primary studies containing epidemiological data on chronic non-cancer pain in Europe excluding studies that solely concerned migraines, headaches and pain associated with specific disease conditions. The studies were prioritised according to quality, recency and validity.

MAIN OUTCOMES

Eighteen research questions concerning aspects of chronic pain included: prevalence; incidence; pain treatments, control and compliance; treatment satisfaction; and quality of life and economic impacts.

RESULTS

The search yielded 16 619 references and 45 were relevant to Europe. Studies for each question were selected that provided the most recent, representative and valid data. There was a clear lack of studies concerning chronic non-cancer pain in Europe as a whole. The 1-month prevalence of moderate-to-severe non-cancer chronic pain was 19%. Chronic pain significantly impacted on patient-perceived health status, affected everyday activities including economic pursuits and personal relationships, and was significantly associated with depressive symptoms. The majority relied on drugs for pain control and NSAIDs were the most frequent drug choice. Despite pain medications, a large proportion had inadequate pain control.

CONCLUSION

To the authors' knowledge this is the most comprehensive literature review on epidemiological data in this field. It is clear that chronic pain has a dramatic impact on European society. Since chronic non-cancer pain is treated differently from cancer-related pain, the lack of data in this area clearly underlines the need for decision makers in healthcare to gather further epidemiological data.

[Anesthesia in drug addiction]

The growing social problem of drug abuse has increased the likelihood that anesthesiologists will find acute or chronic drug users among patients requiring anesthesia for elective or emergency surgery. We must therefore be aware of the effects drugs have on the organism and their possible pharmacokinetic and pharmacodynamic interactions with anesthetic agents in order to prevent complications during surgery and postoperative recovery. Such knowledge is required for the management of abstinence syndrome or overdose, which pose the greatest potential dangers for the hospitalized drug addict.

Pharmacotherapy of low back pain: targeting nociceptive and neuropathic pain components

AIM

To review pharmacological management of chronic low back pain (LBP), with respect to management of nociceptive and neuropathic components.

METHODS

Studies were identified by a PubMed search of English-language papers from the last 10  years, with additional hand searches of relevant reviews.

DISCUSSION

Paracetamol, non-steroidal anti-inflammatory drugs and cyclo-oxygenase-2 inhibitors target the nociceptive component of chronic LBP, and do not affect neuropathic pain mechanisms. Antidepressants target the neuropathic component of chronic LBP; however, conflicting efficacy results have been reported. Opioids target both nociceptive and to a lesser extent neuropathic pain. They are effective in chronic LBP, but many patients require higher doses or combination treatment. The long-term efficacy of opioids in chronic LBP has been questioned because of the absence of high-quality data and concerns regarding tolerability and dependence. The topical preparation lidocaine 5% plaster, indicated in post-herpetic neuralgia, is effective in localized neuropathic pain in patients with chronic LBP. Pregabalin is ineffective as monotherapy for chronic LBP but is effective when combined with celecoxib or opioids. Muscle relaxant monotherapy is ineffective in chronic LBP. Combination therapy is often necessary in patients with chronic LBP, in order to manage both nociceptive and neuropathic pain components.

CONCLUSION

Chronic LBP often comprises both nociceptive and neuropathic components, therefore a multimodal and individualized treatment approach is necessary. Combining drugs with different mechanisms of action (e.g. an agent with µ-receptor activity plus an agent of a different class) represents a rational approach to management of chronic LBP with both nociceptive and neuropathic components.

Factor structure of pain medication questionnaire in community-dwelling older adults with chronic pain

OBJECTIVES

This study was to develop a version of the Pain Medication Questionnaire (PMQ) specific to the elderly chronic pain population and to identify relevant subscales and items for that population. Exploratory factor analysis (EFA) was conducted to assess the factor structure of the PMQ, to eliminate items that are not appropriate for this population, and to improve ease of administration in the elderly population.

METHODS

Data were obtained through a survey administered to older adults with chronic pain who consumed opioid medications in a cross-sectional study at outpatient clinics affiliated with the Baltimore Veterans Affairs Medical Center and the University of Maryland Medical System. EFA was conducted on the PMQ in the geriatric chronic pain population, which was compared with the PMQ studies from the general chronic pain population.

RESULTS

A two-factor solution yielded Factor 1 with four items and Factor 2 with three items; 18 items did not load significantly on either factor, and only seven items loaded significantly on either factor. All of the chosen factor loadings ranged from 0.41 to 0.88.

CONCLUSION

  The findings suggest that, although a small number of the items were identified from the overall scale, they adequately explain two relatively unique factors pertaining to pain management among older adults. This preliminary study suggests that the seven-item PMQ may be useful in assessing opioid medication misuse in community-dwelling older adults with chronic pain. Future studies are needed to confirm the reliability, validity, and factor structure of this modified PMQ in the geriatric population.

Chronic pain management issues in the primary care setting and the utility of long-acting opioids

IMPORTANCE OF THE FIELD

Chronic/persistent pain - a highly prevalent condition that places a substantial burden on patients in terms of personal suffering, reduced productivity and health care costs - remains inadequately treated in many patients. The purpose of this review is to provide an overview and evaluate the burden and undertreatment of chronic/persistent pain, considerations for choosing an analgesic and the utility of long-acting opioids.

AREAS COVERED IN THIS REVIEW

A PubMed search was conducted to identify randomized, placebo-controlled trials evaluating the efficacy and safety of long-acting opioids in chronic pain conditions. The following search terms were used: long-acting opioids, extended-release opioids, controlled-release opioids, sustained-release opioids, and transdermal opioids. The search was limited to randomized, controlled trials published within the last 10 years (1998 - 2008). Studies meeting the following criteria were excluded from review: those focused on a neuropathic pain condition or specific patient subpopulations (e.g., opioid-experienced patients); those conducted outside the USA; and those evaluating a long-acting opioid that is not on the US market at present.

WHAT THE READER WILL GAIN

The reader will first develop a better understanding of the individual and societal ramifications of undertreated chronic pain. Then, a critical review of safety and efficacy data from well-controlled randomized studies will help readers understand the choices and variables that should be considered when selecting appropriate treatments for patients with chronic pain.

TAKE HOME MESSAGE

Successful management of chronic/persistent pain should be individually tailored to each patient, taking into account his or her pain intensity and duration, disease state, tolerance of adverse events and risk of medication abuse or diversion. The literature supports the efficacy and safety of a number of long-acting opioids for the treatment of moderate to severe chronic pain, demonstrating sustained improvements in pain intensity and pain-related sleep disturbances with these agents.

Histopathological and biochemical changes of morphine sulphate administration on the cerebellum of albino rats

In this study the long-term effects of morphine sulphate treatment (MST) on histopathological and biochemical changes in the cerebellum was assessed in albino rats. Normal saline (5ml) was given orally as placebo in the control group (n=25). Morphine groups received morphine orally at a dose level of 5mg/kg body weight day after day for 10, 20 and 30 days (n=25/group). Light microscopy revealed that the molecular layer showed vacuolation. The Purkinje cells lost their specific shaped appearance, decreased in size and numbers. The granular cells highly degenerated. Electron microscopy revealed fragmentation of the cisterns of the both types of endoplasmic reticulum, resulted in a progressive depletion of total protein contents as well as general carbohydrates in all treated groups as supported by histochemical observation. Obvious destruction of mitochondrial inner membrane and cristae mediate cell death. Also, abnormal nucleus with deformed perforated nuclear membrane and deformation of the plasma membrane with degeneration of the synapses could interpreted as a sign of necrosis. Biochemical analysis revealed that dopamine (DA) and norepinephrine (NE) were significantly decreased in four brain areas (cortex striatum, thalamus/hypothalamus, and cerebellum). In contrast, serotonin (5-HT) level was increased in these brain regions; with an exception of 5-HT on day 10 and neurotransmitter levels in the pons were unaffected. The quantitative analysis showed a significant decrease (P<0.05) in the diameter of Purkinje cells and in the thickness of both molecular and granular layers treated groups. Morphine sulphate induces may be a cell death or necrosis in the rat cerebellum and modulating neurotransmitter system. Our findings pointed out the risk of increased cerebellum damage due to long-term of morphine use.

Morphine sulphate induced histopathological and histochemical changes in the rat liver

In this study, the histopathological and histochemical changes due to chronic usage of morphine sulphate in liver were assessed in rats with both light and electron microscopes. Twenty male albino rats (Rattus norvegicus) (130-150 g) were included and divided into four groups. Normal saline (5 ml) was given orally as placebo in the control group (N=5). Morphine groups (N=5) received morphine orally at a single dose of 5 ml/kg/day for 10, 20 and 30 days (groups II, III and IV), respectively. Liver specimens from all groups were evaluated for histopathological and histochemical changes. Light microscopy revealed severe centrilobular congestion, portal fibrosis with bile ductal proliferation and an increased inflammatory infiltration and focal parenchymal necrosis. Histochemical study revealed a progressive depletion of general carbohydrates and an increase in total protein contents. These changes were confirmed at ultrastructural level, including the presence of accumulated lipid in the hepatocytes; deposits of a collagen-like fibrous material were seen in the space of Disse and a reduction in the number of endothelial cell fenestrations. Our findings pointed out the risk of increased lipid fibrosis and hepatic damage due to long-term use of morphine. Although opioids are reported to be effective in pain management, their toxic effects should be kept in mind during chronic usage.

Review of the effect of opioid-related side effects on the undertreatment of moderate to severe chronic non-cancer pain: tapentadol, a step toward a solution?

OBJECTIVE

Opioids are among the most effective and potent analgesics currently available. Their utility in the management of pain associated with cancer, acute injury, or surgery is well recognized. However, extending the application of opioids to the management of chronic non-cancer pain has met with considerable resistance. This resistance is due in part to concerns related to gastrointestinal and central nervous system-related adverse events as well as issues pertaining to regulatory affairs, the development of tolerance, incorrect drug usage, and addiction. This review focuses on the incidence of opioid-related side effects and the patient and physician barriers to opioid therapy for chronic non-cancer pain. Tapentadol, a centrally acting analgesic with two mechanisms of action, micro-opioid agonism and norepinephrine reuptake inhibition, may be considered to be a partial solution to some of these issues.

METHODS

MEDLINE was searched for English-language articles from 1950 to February 2010 using the terms chronic non-cancer pain and opioids together and in combination with undertreatment, adherence, and compliance.

RESULTS

The majority of patients treated with traditional opioids experience gastrointestinal- or central nervous system-related adverse events, most commonly constipation, nausea, and somnolence. These side effects often lead to discontinuation of opioid therapy. Concerns about side effects, analgesic tolerance, dependence, and addiction limit the use of opioids for the management of chronic pain. Treatment with tapentadol appears to provide several advantages of an analgesic with a more favorable side-effect profile than the classic micro-opioid receptor agonist oxycodone (especially related to gastrointestinal tolerability).

CONCLUSIONS

The pervasiveness of opioid-associated side effects and concerns related to tolerance, dependence, and addiction present potential barriers to the approval and use of opioids for the management of chronic non-cancer pain. The lower incidence of opioid-associated adverse events and possibly fewer withdrawal symptoms, combined with a satisfactory analgesic profile associated with tapentadol, suggest its potential utility for the management of chronic non-cancer pain. This review will focus on the incidence of opioid-related side effects and barriers to opioid therapy that are available as English-language articles in the MEDLINE index, and as such, it is a representative but not an exhaustive review of the current literature.

The role of tramadol ER in the treatment of chronic pain

Despite its high prevalence, chronic pain is suboptimally treated in approximately one half of affected patients. Failure to recognise and manage comorbid physical and psychosocial impairments may contribute to the perpetuation of chronic pain. Knowledge of the potential advantages and disadvantages of available analgesic medications will permit informed selection of the appropriate medication for the individual chronic pain patient. Ultimate therapeutic goals will also influence analgesic medication selection. For the patient with chronic pain requiring analgesic treatment for an extended period of time, long-acting analgesics are recommended. Theoretically, these agents will provide sustained analgesia by minimising the end-of-dose pain that is often seen with short-acting medications, with improved patient convenience and a potential for reduced risk of adverse events. The extended-release formulation of tramadol (tramadol ER) has proven efficacy in chronic pain conditions such as osteoarthritis and low back pain, as well as a favourable tolerability profile. In addition, tramadol ER has been shown in clinical trials to improve pain-related sleep disturbances and physical function in patients with chronic pain from osteoarthritis and low back pain.

Opioids and the management of chronic severe pain in the elderly: consensus statement of an International Expert Panel with focus on the six clinically most often used World Health Organization Step III opioids (buprenorphine, fentanyl, hydromorphone, methadone, morphine, oxycodone)

SUMMARY OF CONSENSUS: 1. The use of opioids in cancer pain: The criteria for selecting analgesics for pain treatment in the elderly include, but are not limited to, overall efficacy, overall side-effect profile, onset of action, drug interactions, abuse potential, and practical issues, such as cost and availability of the drug, as well as the severity and type of pain (nociceptive, acute/chronic, etc.). At any given time, the order of choice in the decision-making process can change. This consensus is based on evidence-based literature (extended data are not included and chronic, extended-release opioids are not covered). There are various driving factors relating to prescribing medication, including availability of the compound and cost, which may, at times, be the main driving factor. The transdermal formulation of buprenorphine is available in most European countries, particularly those with high opioid usage, with the exception of France; however, the availability of the sublingual formulation of buprenorphine in Europe is limited, as it is marketed in only a few countries, including Germany and Belgium. The opioid patch is experimental at present in U.S.A. and the sublingual formulation has dispensing restrictions, therefore, its use is limited. It is evident that the population pyramid is upturned. Globally, there is going to be an older population that needs to be cared for in the future. This older population has expectations in life, in that a retiree is no longer an individual who decreases their lifestyle activities. The "baby-boomers" in their 60s and 70s are "baby zoomers"; they want to have a functional active lifestyle. They are willing to make trade-offs regarding treatment choices and understand that they may experience pain, providing that can have increased quality of life and functionality. Therefore, comorbidities--including cancer and noncancer pain, osteoarthritis, rheumatoid arthritis, and postherpetic neuralgia--and patient functional status need to be taken carefully into account when addressing pain in the elderly. World Health Organization step III opioids are the mainstay of pain treatment for cancer patients and morphine has been the most commonly used for decades. In general, high level evidence data (Ib or IIb) exist, although many studies have included only few patients. Based on these studies, all opioids are considered effective in cancer pain management (although parts of cancer pain are not or only partially opioid sensitive), but no well-designed specific studies in the elderly cancer patient are available. Of the 2 opioids that are available in transdermal formulation--fentanyl and buprenorphine--fentanyl is the most investigated, but based on the published data both seem to be effective, with low toxicity and good tolerability profiles, especially at low doses. 2. The use of opioids in noncancer-related pain: Evidence is growing that opioids are efficacious in noncancer pain (treatment data mostly level Ib or IIb), but need individual dose titration and consideration of the respective tolerability profiles. Again no specific studies in the elderly have been performed, but it can be concluded that opioids have shown efficacy in noncancer pain, which is often due to diseases typical for an elderly population. When it is not clear which drugs and which regimes are superior in terms of maintaining analgesic efficacy, the appropriate drug should be chosen based on safety and tolerability considerations. Evidence-based medicine, which has been incorporated into best clinical practice guidelines, should serve as a foundation for the decision-making processes in patient care; however, in practice, the art of medicine is realized when we individualize care to the patient. This strikes a balance between the evidence-based medicine and anecdotal experience. Factual recommendations and expert opinion both have a value when applying guidelines in clinical practice. 3. The use of opioids in neuropathic pain: The role of opioids in neuropathic pain has been under debate in the past but is nowadays more and more accepted; however, higher opioid doses are often needed for neuropathic pain than for nociceptive pain. Most of the treatment data are level II or III, and suggest that incorporation of opioids earlier on might be beneficial. Buprenorphine shows a distinct benefit in improving neuropathic pain symptoms, which is considered a result of its specific pharmacological profile. 4. The use of opioids in elderly patients with impaired hepatic and renal function: Functional impairment of excretory organs is common in the elderly, especially with respect to renal function. For all opioids except buprenorphine, half-life of the active drug and metabolites is increased in the elderly and in patients with renal dysfunction. It is, therefore, recommended that--except for buprenorphine--doses be reduced, a longer time interval be used between doses, and creatinine clearance be monitored. Thus, buprenorphine appears to be the top-line choice for opioid treatment in the elderly. 5. Opioids and respiratory depression: Respiratory depression is a significant threat for opioid-treated patients with underlying pulmonary condition or receiving concomitant central nervous system (CNS) drugs associated with hypoventilation. Not all opioids show equal effects on respiratory depression: buprenorphine is the only opioid demonstrating a ceiling for respiratory depression when used without other CNS depressants. The different features of opioids regarding respiratory effects should be considered when treating patients at risk for respiratory problems, therefore careful dosing must be maintained. 6. Opioids and immunosuppression: Age is related to a gradual decline in the immune system: immunosenescence, which is associated with increased morbidity and mortality from infectious diseases, autoimmune diseases, and cancer, and decreased efficacy of immunotherapy, such as vaccination. The clinical relevance of the immunosuppressant effects of opioids in the elderly is not fully understood, and pain itself may also cause immunosuppression. Providing adequate analgesia can be achieved without significant adverse events, opioids with minimal immunosuppressive characteristics should be used in the elderly. The immunosuppressive effects of most opioids are poorly described and this is one of the problems in assessing true effect of the opioid spectrum, but there is some indication that higher doses of opioids correlate with increased immunosuppressant effects. Taking into consideration all the very limited available evidence from preclinical and clinical work, buprenorphine can be recommended, while morphine and fentanyl cannot. 7. Safety and tolerability profile of opioids: The adverse event profile varies greatly between opioids. As the consequences of adverse events in the elderly can be serious, agents should be used that have a good tolerability profile (especially regarding CNS and gastrointestinal effects) and that are as safe as possible in overdose especially regarding effects on respiration. Slow dose titration helps to reduce the incidence of typical initial adverse events such as nausea and vomiting. Sustained release preparations, including transdermal formulations, increase patient compliance.

The efficacy of oxycodone for management of acute pain episodes in chronic neck pain patients

OBJECTIVE

Most treatments of acute pain associated with non-malignant chronic pains are not satisfactory. The aim of this study is to evaluate the efficacy and side effects of oxycondone controlled release (Oxy-CR) in managing chronic neck pain with acute pain episodes.

DESIGN

Randomised, double-blind, stand controlled study. A total of 116 patients were evenly divided into an oxycodone group (Oxy-CR, 5-10 mg and q12 h/day) and a placebo group (placebo, q12 h/day). Patients were assessed for the frequency of pain flares, visual analgesia score (VAS), quality of life (QOL), quality of sleep (QOS) and adverse effects before the treatment and on days 1, 3, 7, 14, 21 and 28 after the treatment. Withdrawal symptoms were monitored during the study, also on the completion of the entire study. The SF-36 was administered at the beginning and the end of the study for each patient.

RESULTS

Compared with the baselines of Oxy-CR and the placebo groups, the frequency of pain episodes and VAS were decreased significantly starting on day 3 of administration of Oxy-CR (p<0.05). Improvements in QOL and QOS were significant on day 3 after treatment with Oxy-CR (p<0.05). The patients who were treated with Oxy-CR reported significantly higher side effects than the patients in the placebo group (p<0.05). However, these side effects started to diminish after day 7 of the treatment. Withdrawal symptoms did not emerge in this study. Most domains of SF-36 were improved in the treated patients at the end of study (p<0.05).

CONCLUSION

Oxycondone controlled release could be an important optional drug for the management of refractory and frequent acute episodes of chronic neck pain in patients who failed to respond to non-opioid conservative treatment.

Opioid misuse in oncology pain patients

The problem of therapeutic opioid misuse largely affects patients who need opioids to treat chronic pain conditions. Opioid misuse is rarely an overt clinical problem during end of life or acute pain treatment. Misuse attaches a stigma to opioid use, and makes many patients and prescribers reluctant to use these uniquely effective drugs, even when misuse is unlikely. Cancer was once an explosive, typically terminal disease and became the prototype for end-of-life opioid pain treatment. However, cancer is no longer such an explosive disease, and many cancer sufferers can now expect to have a prolonged, even normal, lifespan. They may need pain treatment, but this treatment should not be modeled on palliative care paradigms. This article describes the underlying mechanisms of opioid dependence and its progression to addiction, and suggests a cautious approach to opioid treatment of chronic cancer pain that aims to minimize the problem of misuse.

Opioid dependence and addiction during opioid treatment of chronic pain

Throughout the long history of opioid drug use by humans, it has been known that opioids are powerful analgesics, but they can cause addiction. It has also been observed, and is now substantiated by multiple reports and studies, that during opioid treatment of severe and short-term pain, addiction arises only rarely. However, when opioids are extended to patients with chronic pain, and therapeutic opioid use is not confined to patients with severe and short-lived pain, compulsive opioid seeking and addiction arising directly from opioid treatment of pain become more visible. Although the epidemiological evidence base currently available is rudimentary, it appears that problematic opioid use arises in some fraction of opioid-treated chronic pain patients, and that problematic behaviors and addiction are problems that need to be addressed. Since the potentially devastating effects of addiction can substantially offset the benefits of opioid pain relief, it seems timely to reexamine addiction mechanisms and their relevance to the practice of long-term opioid treatment for pain. This article reviews the neurobiological and genetic basis of addiction, its terminology and diagnosis, the evidence on addiction rates during opioid treatment of chronic pain and the implications of biological mechanisms in formulating rational opioid treatment regimes.

Medication use in a female orofacial pain population

OBJECTIVE

This study compared, both quantitatively and qualitatively, the self-reported medication usage between an adult female orofacial pain population and a comparison group.

STUDY DESIGN

Eighty-seven subjects from both an orofacial pain center (OPC) and undergraduate dental clinic (UDC) completed a standardized medical history questionnaire. Both groups had a similar distribution with regard to age. The number of medications and medication categories were compared between the two groups. Statistical analysis used the Student t-test, Fisher's exact tests, Pearson's chi2 tests, and calculated odds ratios.

RESULTS

The number of pain and non-pain medications, and the number of medication categories endorsed by OPC subjects was significantly higher compared with the UDC group.

CONCLUSION

Adult female orofacial pain subjects report greater overall and higher rate of medication use, which was not limited to only the analgesic/narcotic categories, than the comparison group.

Long-term management of chronic pain with transdermal buprenorphine: a multicenter, open-label, follow-up study in patients from three short-term clinical trials

BACKGROUND

Transdermal buprenorphine is available in Europe for the treatment of moderate to severe chronic pain. It has been evaluated at doses of 35, 52.5, and 70 microg/h for the management of moderate to severe chronic cancer and noncancer pain in 3 randomized, double-blind, placebo-controlled trials, each of limited duration (approximately 14 days each). Long-term data are essential to determining the performance of an analgesic in the management of chronic pain.

OBJECTIVE

The purpose of this follow-up study was to obtain data on the efficacy and tolerability of long-term treatment with transdermal buprenorphine in cancer and noncancer patients with chronic persistent pain of moderate to severe intensity.

METHODS

This was an open-label, uncontrolled, follow-up study in patients from the 3 previous clinical trials who elected to continue treatment with transdermal buprenorphine 35 microg/h and sublingual buprenorphine tablets (0.2 mg) as needed for breakthrough pain. The patch was to be changed every 72 hours throughout the patient's course of pain therapy. At visits every 2 weeks for the first 4 weeks and every 4 weeks for the remainder of study participation, patients evaluated their pain relief retrospectively on a 4-point verbal rating scale. They also rated the ease of patch handling using a 3-point verbal rating scale. Patterns of dose escalation and dose stability were monitored over time. Adherence to therapy was determined based on the number of patients who complied with the dosing schedule. Adverse events were documented by type, intensity, location (systemic or local), and relationship to study medication.

RESULTS

Two hundred thirty-nine patients were included in this follow-up study (120 women, 119 men; 100% white; mean [SD] age, 58 [11.3] years; mean weight, 70.8 [14.7] kg). One hundred thirty-four had cancer-related pain and 105 had pain of noncancerous origin. The mean duration of participation was 7.5 months, and 37 (15.5%) patients participated for >12 months. Maximum study participation was 3.4 years in cancer patients and 5.7 years in noncancer patients. One hundred eighty-eight (78.7%) patients were considered adherent to therapy. The majority (65.9%) of patients managed their pain with the patchalone or took no more than 1 additional sublingual tablet daily for breakthrough pain. At least satisfactory pain relief was reported by 215 (90.0%) patients, and the buprenorphine patch was generally well tolerated. The most common systemic adverse drug reactions were nausea (9.2%), dizziness (4.6%), vomiting (4.2%), constipation (3.8%), and tiredness (2.9%), whereas the most common local adverse drug reactions were erythema (12.1%), pruritus (10.5%), and exanthema (8.8%).

CONCLUSION

Transdermal buprenorphine was generally well tolerated and effective for the long-term treatment of chronic cancer or noncancer pain in these patients who had previously received buprenorphine in 3 short-term clinical trials.

Transdermal buprenorphine in pain management--experiences from clinical practice: Five case studies

Buprenorphine is a semi-synthetic opioid derived from thebaine. The transdermal formulation of buprenorphine has been available in Belgium for 3 years, during which time the Pain Clinic of the St Elisabeth of Verviers Hospital has gained experience in the use of transdermal buprenorphine for the treatment of moderate-to-severe pain. This paper presents four cases of chronic, non-malignant pain, and one case of chronic cancer pain. By starting patients on low doses and slowly titrating upwards, transdermal buprenorphine matrix patches provided effective analgesia and were well tolerated. Low doses of transdermal buprenorphine were created by cutting the smallest available matrix patch (35 mug/h) into halves or quarters. The initial dose was then gradually titrated upwards to the dose needed for optimum pain relief by the patients. No problems were encountered in switching patients from prior analgesic therapy with other opioids to transdermal buprenorphine.

Opioids for chronic noncancer pain: a meta-analysis of effectiveness and side effects

BACKGROUND

Chronic noncancer pain (CNCP) is a major health problem, for which opioids provide one treatment option. However, evidence is needed about side effects, efficacy, and risk of misuse or addiction.

METHODS

This meta-analysis was carried out with these objectives: to compare the efficacy of opioids for CNCP with other drugs and placebo; to identify types of CNCP that respond better to opioids; and to determine the most common side effects of opioids. We searched MEDLINE, EMBASE, CENTRAL (up to May 2005) and reference lists for randomized controlled trials of any opioid administered by oral or transdermal routes or rectal suppositories for CNCP (defined as pain for longer than 6 mo). Extracted outcomes included pain, function or side effects. Methodological quality was assessed with the Jadad instrument; analyses were conducted with Revman 4.2.7.

RESULTS

Included were 41 randomized trials involving 6019 patients: 80% of the patients had nociceptive pain (osteoarthritis, rheumatoid arthritis or back pain); 12%, neuropathic pain (postherpetic neuralgia, diabetic neuropathy or phantom limb pain); 7%, fibromyalgia; and 1%, mixed pain. The methodological quality of 87% of the studies was high. The opioids studied were classified as weak (tramadol, propoxyphene, codeine) or strong (morphine, oxycodone). Average duration of treatment was 5 (range 1-16) weeks. Dropout rates averaged 33% in the opioid groups and 38% in the placebo groups. Opioids were more effective than placebo for both pain and functional outcomes in patients with nociceptive or neuropathic pain or fibromyalgia. Strong, but not weak, opioids were significantly superior to naproxen and nortriptyline, and only for pain relief. Among the side effects of opioids, only constipation and nausea were clinically and statistically significant.

INTERPRETATION

Weak and strong opioids outperformed placebo for pain and function in all types of CNCP. Other drugs produced better functional outcomes than opioids, whereas for pain relief they were outperformed only by strong opioids. Despite the relative shortness of the trials, more than one-third of the participants abandoned treatment.

Using opioids with persisting noncancer pain: a biopsychosocial perspective

OBJECTIVE

Despite the growing use of opioids for persisting noncancer pain, evidence for their effectiveness is limited, especially in relation to functional outcomes. Guidelines have been developed for prescribers, but their utility is untested. This review examines the use of opioids in this population from a biopsychosocial perspective and makes a number of recommendations.

DATA SOURCES

Published comparison studies and reviews of oral opioids in chronic noncancer pain, as well as 5 published guidelines for the prescription of opioids and systematic reviews of cognitive-behavioral pain management programs.

METHODS

Outcomes of the opioid comparison studies were reviewed and compared to those achieved by pain management programs.

CONCLUSIONS

The available evidence indicates that by themselves, oral opioids generally achieve only modest reductions in pain levels in patients with chronic noncancer pain. Functional outcomes are inconsistent across studies. There are questions about the timing of their use and patient selection. There are risks in trials of opioids only after other conservative interventions have been tried unsuccessfully. Also, in some patients, ongoing use of opioids risks repeated over-doing of pain-generating activities and reinforcing escape/avoidance responses that promote disability. These risks may be lessened by assessment of current use of pain self-management strategies among potential candidates for opioids. This offers advantages in promoting collaborative management of persisting pain as well as better pain and functional outcomes. In this view, opioids may be considered as one possible element of a management plan rather than the primary treatment.

HS014, a selective melanocortin-4 (MC4) receptor antagonist, modulates the behavioral effects of morphine in mice

RATIONALE

Melanocortin and opioid systems regulate feeding as well as other behaviors; however, the relationship between the two systems is not yet defined. Since agonist-induced stimulation of melanocortin receptors blocks the behavioral effects of mu opioid receptor agonists, and melanocortin-4 (MC4) receptors and mu opioid receptors share a similar anatomical distribution in the central nervous system, MC4 receptor blockade may increase opioid responsiveness.

OBJECTIVES

The goal of this study was to test the hypothesis that blockade of MC4 receptors increases the behavioral effects of morphine.

METHODS

The effects of HS014 (0.0032, 0.032, and 1 nmol, i.c.v.), a selective MC4 antagonist, on morphine-induced (3.2, 10, and 32 mg/kg, i.p.) locomotor activity (measured in the open field for 15 min) and antinociception (measured in the hot plate at 55 degrees C) were assessed in C57Bl/6 mice. In addition, the effects of morphine were evaluated in A(y) mice, a genetic model for MC4 receptor blockade.

RESULTS

The dose-effect curve of morphine for locomotor activity was shifted downwards in C57Bl/6 mice pretreated with HS014 and in A(y) mice. The dose-effect curve of morphine for antinociception was shifted two- and threefold to the left in C57Bl/6 mice pretreated with HS014 and in A(y) mice, respectively.

CONCLUSIONS

These results indicate that blockade of MC4 receptors increases the antinociceptive effects of morphine without changing the potency of morphine for locomotor activity, suggesting that MC4 receptor antagonists may be candidate drugs that can be clinically used for the treatment of pain.

Liver and kidney toxicity in chronic use of opioids: An experimental long term treatment model

In this study, histopathological and biochemical changes due to chronic usage of morphine or tramadol in liver and kidney were assessed in rats. Thirty male Wistar rats (180-220 g) were included and divided into three groups. Normal saline (1 ml) was given intraperitoneally as placebo in the control group (n = 10). Morphine group (n = 10) received morphine intraperitoneally at a dose of 4, 8, 10 mg/kg/day in the first, second and the third ten days of the study, respectively. Tramadol group (n = 10), received the drug intraperitoneally at doses of 20, 40 and 80 mg/kg/day in the first, second and the third ten days of the study, respectively. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatinin, blood urea nitrogen (BUN) and malondialdehyde (MDA) levels were measured in the serum. Liver and kidney specimens were evaluated by light microscopy. Serum ALT, AST, LDH, BUN and creatinin levels were significantly higher in morphine group compared to the control group. Serum LDH, BUN and creatinin levels were significantly increased in the morphine group compared to the tramadol group. The mean MDA level was significantly higher in morphine group compared to the tramadol and control groups (P < 0.05). Light microscopy revealed severe centrolobular congestion and focal necrosis in the liver of morphine and tramadol groups, but perivenular necrosis was present only in the morphine group. The main histopathologic finding was vacuolization in tubular cells in morphine and tramadol groups. Our findings pointed out the risk of increased lipid peroxidation, hepatic and renal damage due to long term use of opioids, especially morphine. Although opioids are reported to be effective in pain management, their toxic effects should be kept in mind during chronic usage.

Postoperative Care of the Chronic Opioid-Consuming Patient

Recently, there has been a significant increase in the use of opioid analgesics for chronic pain in the outpatient setting. As a result, anesthesiologists are commonly presented with the dilemma of treating acute postoperative pain in patients who do not receive adequate analgesia with conventional doses of opioid. This article presents a practical approach to treating postoperative pain in the chronic opioid-consuming patient. Specifically, a technique based on pharmacokinetic modeling is described that predicts safe and therapeutic opioid dosing in these patients.

Perioperative and Intraoperative Pain and Anesthetic Care of the Chronic Pain and Cancer Pain Patient Receiving Chronic Opioid Therapy

The expanding role of the anesthesiologist as a "perioperative physician" places ever-increasing demands upon his or her clinical skills and knowledge. One area of growing concern for the anesthesiologist involves the perioperative assessment and management of the opioid-tolerant chronic pain patient. Opioids occupy a position of unsurpassed clinical utility for the treatment of many types of painful conditions. Coupled with noticeable shifts in physician attitudes that have occurred in recent years regarding the use of opioids for the treatment of benign and malignancy-related pain, many more patients are presenting for surgical procedures who are opioid tolerant. It is important therefore that the practicing anesthesiologist become familiar with the currently available opioid formulations, including drug interactions and side effects, in order to better plan the patient's perioperative anesthetic needs and management. Unfortunately, there is a lack of scientifically rigorous studies in this important area, and most of the information must be derived from anecdotal reports and personal experience of anesthesiologists working in this field. In this review, we shall discuss some aspects of current chronic pain management, the newer forms of opioid administration which may be unfamiliar to the anesthesiologist, as well as clinical aspects of opioid use and tolerance including the impact it may have on perioperative anesthetic management.

Is the Effect of Inguinal Field Block With 0.5% Bupivacaine on Postoperative Pain After Hernia Repair Enhanced by Addition of Ketorolac or S(+) Ketamine?

OBJECTIVE

The aim of the study was to assess whether coadministration of S(+) ketamine or ketorolac would enhance or prolong local analgesic effect of bupivacaine after inguinal hernia repair.

DESIGN

Prospective double-blind randomized study evaluating pain intensity after surgery under general anesthesia.

SETTING

Outpatient facilities of the University Hospital of Lausanne.

PATIENT

Thirty-six ASA I-II outpatients scheduled for elective day-case inguinal herniorraphy.

INTERVENTION

Analgesia strategy consisted of a wound infiltration and an inguinal field block either with 30 mL bupivacaine (0.5%) or with the same volume of a mixture of 27 mL bupivacaine (0.5%) + 3 mL S(+) ketamine (75 mg) or a 28 mL bupivacaine (0.5%) + 2 mL ketorolac (60 mg). Postoperative analgesic regimen was standardized.

OUTCOME MEASURES

Pain intensity was assessed with a Visual Analog Scale, a verbal rating score, and by pressure algometry 2, 4, 6, 24, and 48 hours after surgery.

RESULTS

The 3 groups of patients experienced the highest Visual Analog Scale pain score at 24 hours, which was different from those at 6 and 48 hours (P < 0.05). Apart from a significantly lower pain sensation (verbal rating score) in the ketorolac group at 24 and 48 hours and only at 48 hours with ketamine, there were no other differences in pain scores, pain pressure thresholds, or rescue analgesic consumption between groups throughout the 48-hour study period.

CONCLUSION

The addition of S(+)-ketamine or ketorolac only minimally improves the analgesic effect of bupivacaine. This may be related to the tension-free hernia repair technique associated with low postoperative pain.

Transdermal buprenorphine in the treatment of chronic pain: Resultsof a phase III, multicenter, randomized, double-blind, placebo-controlled study

BACKGROUND

Buprenorphine, a potent opioid analgesic, has been available in parenteral and oral or sublingual(SL) formulations for >25 years. In 2001, the buprenorphine transdermal delivery system (TES) was introduced at 3 release rates (35, 52.5, and 70 microg/h) for the treatment of chronic cancer and noncancer pain.

OBJECTIVE

This study compared the analgesic efficacy and tolerability of buprenorphine TES at a release rate of 35 microg/h with those of buprenorphine SL and placebo in patients with severe or very severe chronic cancer or noncancer pain.

METHODS

This multicenter, double-blind, placebo-controlled, parallel-group trial was 1 of 3 Phase III studies involved in the clinical development of buprenorphine TDS. It comprised a 6-day open-label run-in phase in which patients received buprenorphine SL 0.8 to 1.6 mg/d as needed and a double-blind phase in which patients were randomized to receive 3 sequential patches containing buprenorphine TES 35 microg/h or placebo, each lasting 72 hours. Rescue analgesia consisting of buprenorphine SL 02-mg tablets was available as needed throughout the double-blind phase. The main outcome measures were (1) the number of buprenorphine SL tablets required in addition to buprenorphine TES during the double-blind phase compared with the placebo group and compared with the buprenorphine SL requirement during the run-in phase, and (2) patients' assessments of pain intensity, pain relief, and duration of sleep uninterrupted by pain in the double-blind phase compared with the run-in phase. Adverse events were documented throughout the study.

RESULTS

One hundred thirty-seven patients were included in the double-blind phase (90 buprenorphine TES, 47 placebo). The buprenorphine TES group included 47 men and 43 women (mean [SD] age, 56.0 [12.1] years), and the placebo group included 23 men and 24 women (mean age, 55.7 [12.9] years). Forty-five patients had cancer-related pain and 92 had noncancer-related pain. The 2 treatment groups were comparable with respect to sex distribution, age, height, and body weight Patients receiving buprenorphine TES significantly reduced their consumption of buprenorphine SL tablets in the double-blind phase compared with patients receiving placebo (reduction of 0.6 [0.4] mg vs 0.4 [0.4] mg; P = 0.03). The relationship between the buprenorphine SL dose in the run-in phase and the number of buprenorphine SL tablets required in the double-blind phase was dose dependent in the active-treatment group only. Patients' assessments of pain intensity and pain relief suggested better analgesia with buprenorphine TES than with placebo, although the differences did not reach statistical significance. The proportion of patients who reported sleeping for >6 hours uninterrupted by pain in the double-blind phase compared with the run-in phase increased by 6.4% in the buprenorphine TDS group (35.6% vs 292%, respectively), compared with a decrease of 5.9% in the placebo group (40.4% vs 463%); no statistical analysis of sleep duration data was performed. Buprenorphine TDS was well tolerated, with adverse events generally similar to those associated with other opioids. The incidence of systemic adverse events in the double-blind phase was similar in the 2 treatment groups (28.9% buprenorphine TDS, 27.6% placebo), with the most common adverse events being nausea, dizziness, and vomiting. After patch removal, skin reactions (mainly mild or moderate pruritus and erythema) were seen in 35.6% of the buprenorphine TDS group and 25.5% of the placebo group.

CONCLUSIONS

In the population studied, buprenorphine TDS provided adequate pain relief, as well as improvements in pain intensity and duration of pain-free sleep. It may be considered a therapeutic option for the treatment of moderate to severe chronic pain.

Chronic noncancer pain rehabilitation with opioid withdrawal: comparison of treatment outcomes based on opioid use status at admission

OBJECTIVE

To study differences in treatment outcomes between patients with chronic noncancer pain taking vs those not taking maintenance opioids at admission to a pain rehabilitation program.

PATIENTS AND METHODS

A nonrandomized 2-group prepost design was used to compare 356 patients admitted to the Mayo Comprehensive Pain Rehabilitation Center from January 2002 to December 2002 at admission and discharge by opioid status at admission. Measures of pain severity, interference due to pain, perceived life control, affective distress, activity level, depression, and catastrophizing (an exaggerated negative mental set associated with actual or anticipated pain experiences) were used to compare opioid and nonopioid groups. The patients entered a 3-week intensive outpatient multidisciplinary pain rehabilitation program designed to improve adaptation to chronic noncancer pain. The program uses a cognitive-behavioral model and incorporates opioid withdrawal.

RESULTS

More than one third of patients (135/356) were taking opioids daily at admission. At completion of the program, all but 3 of the 135 patients had successfully discontinued opioid treatment. No significant pretreatment differences were found between the opioid and nonopioid group regarding demographics, pain duration, treatment completion, or all outcome variables, including pain severity. Significant improvement was noted at discharge for all outcome variables assessed regardless of opioid status at admission.

CONCLUSION

Patients with symptomatically severe and disabling pain while taking maintenance opioid therapy can experience significant improvement in physical and emotional functioning while participating in a pain rehabilitation program that incorporates opioid withdrawal.