Benefit-risk assessment and reporting in clinical trials of chronic pain treatments: IMMPACT recommendations.

ABSTRACT: Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. This article was motivated by an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting and is based on the expert opinion of those who attended. In addition, a review of the benefit-risk assessment tools used in published chronic pain RCTs or highlighted by key professional organizations (ie, Cochrane, European Medicines Agency, Outcome Measures in Rheumatology, and U.S. Food and Drug Administration) was completed. Overall, the review found that benefit-risk metrics are not commonly used in RCTs of chronic pain despite the availability of published methods. A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.

Research design considerations for chronic pain prevention clinical trials: IMMPACT recommendations.

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

The Potential Role of Sensory Testing, Skin Biopsy, and Functional Brain Imaging as Biomarkers in Chronic Pain Clinical Trials: IMMPACT Considerations.

Valid and reliable biomarkers can play an important role in clinical trials as indicators of biological or pathogenic processes or as a signal of treatment response. Currently, there are no biomarkers for pain qualified by the U.S. Food and Drug Administration or the European Medicines Agency for use in clinical trials. This article summarizes an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting in which 3 potential biomarkers were discussed for use in the development of analgesic treatments: 1) sensory testing, 2) skin punch biopsy, and 3) brain imaging. The empirical evidence supporting the use of these tests is described within the context of the 4 categories of biomarkers: 1) diagnostic, 2) prognostic, 3) predictive, and 4) pharmacodynamic. Although sensory testing, skin punch biopsy, and brain imaging are promising tools for pain in clinical trials, additional evidence is needed to further support and standardize these tests for use as biomarkers in pain clinical trials. PERSPECTIVE: The applicability of sensory testing, skin biopsy, and brain imaging as diagnostic, prognostic, predictive, and pharmacodynamic biomarkers for use in analgesic treatment trials is considered. Evidence in support of their use and outlining problems is presented, as well as a call for further standardization and demonstrations of validity and reliability.

Assessment of physical function and participation in chronic pain clinical trials: IMMPACT/OMERACT recommendations.

Although pain reduction is commonly the primary outcome in chronic pain clinical trials, physical functioning is also important. A challenge in designing chronic pain trials to determine efficacy and effectiveness of therapies is obtaining appropriate information about the impact of an intervention on physical function. The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) and Outcome Measures in Rheumatology (OMERACT) convened a meeting to consider assessment of physical functioning and participation in research on chronic pain. The primary purpose of this article is to synthesize evidence on the scope of physical functioning to inform work on refining physical function outcome measurement. We address issues in assessing this broad construct and provide examples of frequently used measures of relevant concepts. Investigators can assess physical functioning using patient-reported outcome (PRO), performance-based, and objective measures of activity. This article aims to provide support for the use of these measures, covering broad aspects of functioning, including work participation, social participation, and caregiver burden, which researchers should consider when designing chronic pain clinical trials. Investigators should consider the inclusion of both PROs and performance-based measures as they provide different but also important complementary information. The development and use of reliable and valid PROs and performance-based measures of physical functioning may expedite development of treatments, and standardization of these measures has the potential to facilitate comparison across studies. We provide recommendations regarding important domains to stimulate research to develop tools that are more robust, address consistency and standardization, and engage patients early in tool development.

A multicenter, primary care-based, open-label study to identify behaviors related to prescription opioid misuse, abuse, and diversion in opioid-experienced patients with chronic moderate-to-severe pain.

OBJECTIVE: To compare the investigator assessment of patient risk for prescription opioid misuse, abuse, and diversion with patient self-reports of these activities in a population with chronic pain. METHODS: As a secondary objective of an open-label, multicenter, primary care-based clinical study to evaluate the success of converting opioid-experienced patients with chronic pain to morphine sulfate with sequestered naltrexone hydrochloride, risk for misuse, abuse, and diversion was assessed using two nonvalidated questionnaires: one was completed by the investigator and another by the patient (Self-Reported Misuse, Abuse, and Diversion [SR-MAD]). In addition, the validated Current Opioid Misuse Measure (COMM) test and urine drug test were used. RESULTS: Of the 684 patients assessed by the investigators, 537 returned the self-assessment, SR-MAD. Most patients were assigned by the investigator as low risk for misuse (84.2%), abuse (89.3%), and diversion (94.3%). Of the patients who returned SR-MAD, 60% indicated having taken more opioids than prescribed and 10.9% reported chewing or crushing their opioids in the past. Of the patients who completed COMM, 40.6% were deemed as having aberrant behaviors. COMM results correlated with the risk levels from the investigator assessment. One-third of patients (33.8%) had at least one abnormal urine drug test result. CONCLUSION: More research is needed to better understand the gap between the investigator assessment of potential risk for misuse, abuse, and diversion and the actual extent of these behaviors among patients with chronic pain.

A multicenter, primary-care-based, open-label study to assess the success of converting opioid-experienced patients with chronic moderate-to-severe pain to morphine sulfate and naltrexone hydrochloride extended-release capsules using a standardized conversion guide.

OBJECTIVE: To evaluate the conversion of opioid-experienced patients with chronic moderate-to-severe pain to extended-release morphine sulfate with sequestered naltrexone hydrochloride (MSN) using a standardized conversion guide. METHODS: This open-label, single-arm study was conducted in 157 primary care centers in the United States. A total of 684 opioid-experienced adults with chronic moderate-to-severe pain were converted to oral administration of MSN from transdermal fentanyl and oral formulations of hydrocodone, hydromorphone, methadone, oxycodone, oxymorphone, and other morphine products using a standardized conversion guide. The primary endpoint was the percentage of patients achieving a stable MSN dose within a 6-week titration phase. Secondary endpoints included duration of time to stable dose, number of titration steps, safety and efficacy measures, and investigator assessment of conversion guide utility. RESULTS: Of the 684 patients, 51.3% were converted to a stable dose of MSN (95% confidence interval: 47.5%, 55.1%). The mean (standard deviation) number of days to stable dose was 20 (8.94), and number of titration steps to stable dose was 2.4 (1.37). The majority of adverse events were mild/moderate and consistent with opioid therapy. Mean pain scores at stable dose decreased from baseline. Investigators were generally satisfied with the conversion guide and, in 94% of cases, reported they would use it again. CONCLUSION: Conversion to MSN treatment using the standardized MSN conversion guide was an attainable goal in approximately half of the population of opioid-experienced patients with chronic moderate-to-severe pain. Investigators found the guide to be a useful tool to assist conversion of opioid-experienced patients to MSN.

Research design considerations for chronic pain prevention clinical trials: IMMPACT recommendations.

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

Self-reports of prescription opioid abuse and diversion among recreational opioid users in a Canadian and a United States city.

OBJECTIVE: To explore behaviors related to prescription opioid abuse and diversion in individuals who self-reported past recreational (nonmedical) opioid use. DESIGN: A questionnaire was developed and included in two abuse potential clinical studies conducted in Canada (Toronto, ON, August 2010 to January, 2011) and the United States (Salt Lake City, UT, February-May 2011). PARTICIPANTS: Recreational opioid users. MAIN OUTCOME MEASURE(S): Self-reported behaviors related to prescription opioid abuse and diversion. RESULTS: The questionnaire was completed by 174 participants in the Canadian study and 80 participants in the US study. Most participants reported that they used prescription opioids for nonmedical purposes a few times a month. Most had taken their first prescription opioid between the ages of 12 and 24 years and the two most common reasons were to treat pain or to feel high/stoned. When asked about specific opioids taken for nonmedical purposes in the past year, oxycodone, acetaminophen with codeine, and morphine were commonly used by both cohorts, whereas hydrocodone use was substantially greater in the US cohort versus the Canadian cohort. Participants reported various tampering methods and routes of administration, with swallowed whole, crushed and snorted, and chewed/crushed and swallowed as the most prevalent. Most participants indicated taking other drugs with prescription opioids to get high, most commonly marijuana and alcohol. The most common sources for obtaining prescription opioids were family/friends. CONCLUSIONS: Two cohorts of recreational opioid users from Canada and the United States reported similar experiences with various prescription opioids and indicated a predominance of diversion from family/friends.

A multicenter, 12-month, open-label, single-arm safety study of oxycodone-hydrochloride/naltrexone-hydrochloride extended-release capsules (ALO-02) in patients with moderate-to-severe chronic noncancer pain.

OBJECTIVE: To evaluate the long-term safety of oxycodone-hydrochloride and sequestered naltrexone-hydrochloride (ALO-02) administered for up to 12 months. DESIGN: Open-label, single-arm safety study. SETTING: Thirty-two US research centers (ClinicalTrials.gov identifier NCT01428583). PATIENTS: Three hundred ninety-five adults (opioid experienced and opioid naïve) with moderate-to-severe chronic noncancer pain (CNCP). INTERVENTIONS: Open-label, oral ALO-02 capsules, daily dose ranging from 20 to 160 mg oxycodone for up to 12 months. MAIN OUTCOME MEASURES: Number and type of adverse events (AEs) and drugrelated AEs, including assessments of withdrawal (Clinical Opiate Withdrawal Scale; COWS), pharmacokinetics, efficacy, and aberrant behaviors (Current Opioid Misuse Measure). RESULTS: A total of 193 (48.9 percent) patients received ALO-02 for ≥181 days and 105 (26.6 percent) patients for ≥361 days. The most common treatment-emergent AEs were nausea (25.3 percent), constipation (21.3 percent), vomiting (13.9 percent), and headache (11.6 percent). The most common drug-related AEs were constipation (18.0 percent), nausea (14.9 percent), somnolence (8.4 percent), fatigue (6.8 percent), dizziness (5.6 percent), and vomiting (5.1 percent). A majority of patients (86.6 percent) had a maximum COWS total score below the level for mild withdrawal symptoms at every visit throughout the study. Pain severity scores as measured by the short Form of the Brief Pain Inventory (BPI-SF) decreased over time. CONCLUSIONS: Repeat dosing of ALO-02 for up to 12 months is safe and well tolerated in a CNCP population of both opioid-experienced and opioid-naïve patients. ALO-02 demonstrated a safety profile consistent with extended-release opioids and the expected analgesic efficacy. The addition of sequestered naltrexone had no significant clinical effect on patients when taken as directed.

Emotional reactions to pain predict psychological distress in adult patients with Sickle Cell Disease (SCD).

Differentiating somatic from emotional influences on the experience of chronic pain has been of interest to clinicians and researchers for many years. Although prior research has not well specified these pathways at the anatomical level, some evidence, both theoretical and empirical, suggest that emotional reactions influence the experience of disease and non-disease-related pains. Other studies suggest that treatments directed at negative emotional responses reduce suffering associated with pain. The current study was conducted to explore the influence of emotional reactions to pain as a predictor of psychological distress in a sample of adult Blacks with Sickle Cell Disease (SCD). Using cross-sectional survey data, we evaluated whether negative emotional reactions to the experience of pain were predictive of psychological distress after controlling for the somatic dimension of pain and age in n = 67 Black patients with Sickle Cell Disease (SCD). Results showed that greater negative emotion associated with pain predicted Somatization (p < .01), Anxiety (p < .05), Phobic Anxiety (p < .05), and Psychoticism (p < .05). Increased negative emotion associated with pain was also predictive of the General Symptoms Index (p < .05) and the Positive Symptoms Total from the SCL-90-R (p < .01). We believe the current study demonstrates that negative emotional reactions to the experience of pain in adults with SCD are predictive of psychological distress above and beyond the influences of age and the direct nociceptive experience. We also believe these data to be valuable in conceptualizing the allocation of treatment resources toward a proactive approach with early identification of patients who are responding poorly for the purpose of potentially reducing later psychopathology. A deeper understanding of the ways that subpopulations cope with chronic disease-related pain may produce models that can be ultimately generalized to the consumers of the majority of healthcare resources.

A double-blind, randomized, placebo-controlled trial of a diazepam auto-injector administered by caregivers to patients with epilepsy who require intermittent intervention for acute repetitive seizures.

PURPOSE: A diazepam auto­injector (AI) has been developed for intramuscular administration to treat acute repetitive seizures (ARS). The objective of this study was to evaluate the efficacy and safety of the diazepam AI when administered by caregivers to control an episode of ARS (ClinicalTrials.gov identifier NCT00319501). METHODS: In this phase III, randomized, double­blind, parallel­group, placebo­controlled, multicenter study, subjects with epilepsy on a stable antiepileptic drug regimen who required intermittent medical intervention to control ARS were randomized 1:1 to the placebo AI or the diazepam AI group. Subjects were stratified according to age (2­5, 6­11, ≥12 years). Dose (5, 10, 15, or 20 mg) was based on age and weight. A single dose of study medication was dispensed to be administered by caregivers in an outpatient setting when required. The primary end point was time to next seizure or rescue from 15 min to 12 h postdose. Secondary end points included rescue medication use, number of seizures postdose, caregiver and physician treatment assessments, and safety measures. KEY FINDINGS: Of 234 subjects randomized, 81/110 in the placebo AI group and 82/124 in the diazepam AI group were included in the intent­to­treat analysis. Baseline characteristics were similar for both groups. Time to next seizure or rescue was significantly longer in the diazepam AI group compared with the placebo AI group, with a hazard ratio of 0.55 (95% confidence interval [CI] 0.34­0.88; p = 0.012) for diazepam AI versus placebo AI, adjusted for age group. The 25th percentile for time to the next seizure or rescue was 1.18 h (95% CI 0.38­2.03) for placebo AI and 2.70 h (95% CI 0.48­11.42) for diazepam AI; the median was 5.9 h for placebo AI and was inestimable for diazepam AI due to the low number of events experienced by subjects in that group. The proportion of subjects using rescue medication postdose was 30% (24/81) placebo AI versus 17% (14/82) diazepam AI (p = 0.066). An event (seizure or rescue) occurred in 55.6% of subjects in the placebo AI group and 35.4% in the diazepam AI group. The number of seizures experienced during the 12­h postdose period was significantly lower for diazepam AI (median 0.0) compared with placebo AI (median 1.0; p = 0.010). Treatment­emergent adverse events (TEAEs) were reported in 44% (35/79) of subjects in the placebo AI group and 42% (34/81) in the diazepam AI group. The most common TEAEs reported were injection site pain (15% placebo AI, 17% diazepam AI) and injection site hemorrhage (6% placebo AI, 5% diazepam AI). SIGNIFICANCE: The diazepam AI was significantly more effective than placebo AI at delaying the next seizure or rescue. Secondary efficacy end points were generally supportive of the primary outcome. Diazepam AI administered by trained caregivers was effective for the treatment of ARS and was well tolerated, with a safety profile similar to placebo.

Assessing the subjective and physiological effects of intranasally administered crushed extended-release morphine formulations with and without a sequestered naltrexone core in recreational opioid users.

OBJECTIVE: To evaluate the pharmacodynamic (PD) effects of morphine sulfate and naltrexone hydrochloride extended-release (MSN) capsules compared with controlled-release morphine sulfate (MS) and placebo when crushed and administered intranasally. METHODS: The present study was a randomized, double-blinded, placebo-controlled, single-dose (30 mg), three-way crossover study in healthy, nondependent recreational opioid users. PD measures included assessment of subjective drug effects using visual analogue scales (VAS) ranging from 0 to 100 and assessments of pupil diameter. Blood samples were collected for pharmacokinetic analyses. RESULTS: Both MS and MSN showed significantly higher PD values compared with placebo. MSN showed significantly lower scores for drug liking and high VAS scores on both mean peak effect (Emax) (69.6 and 55.2, respectively) and in area under the effect curve over 2 h (86.3 and 66.7, respectively) following dosing compared with MS (Emax 87.6 and 86.6, respectively; area under the curve over 2 h 120.6 and 132.9, respectively; P<0.001). MSN showed significantly lower Emax for all other positive subjective effects (good drug effects, overall drug liking, and take drug again VAS scores) compared with MS (P<0.001). Peak minimum pupil diameter was significantly larger for MSN than MS (P=0.002). Mean peak plasma concentration (Cmax) and median time to Cmax for morphine following administration of MSN and MS were similar (27.3 ng/mL and 0.57 h versus 27.7 ng/mL and 0.6 h, respectively). Naltrexone mean Cmax was 1497 pg/mL after MSN and median time to Cmax was 0.55 h. CONCLUSIONS: When crushed and administered intranasally, MSN was associated with significantly lower ratings of drug liking and other positive subjective effects compared with MS.

Assessment of pharmacodynamic effects following oral administration of crushed morphine sulfate and naltrexone hydrochloride extended-release capsules compared with crushed morphine sulfate controlled-release tablets and placebo in nondependent recreational opioid users.

OBJECTIVES: To compare the pharmacodynamic effects, including self-reports of "drug liking" and "high," of crushed morphine sulfate and naltrexone hydrochloride extended-release capsules (MSN), crushed morphine sulfate controlled-release (CR) tablets, and placebo in an abuse potential study. DESIGN: Randomized, double-blind, placebo-controlled, three-way crossover study. SETTING: Single-center. SUBJECTS: Nondependent recreational opioid users. INTERVENTIONS: Orally administered crushed MSN (120-mg morphine sulfate and 4.8-mg naltrexone hydrochloride), crushed 120-mg morphine sulfate CR, and placebo. OUTCOME MEASURES: Subjective ratings (100-point visual analog scales) of positive drug effects (drug liking, high, good effects, take drug again, and overall drug liking), any effects, and negative effects (bad effects, feel sick, nausea, sleepy, and dizzy), along with pupillometry, pharmacokinetic (PK), and safety assessments. RESULTS: Crushed morphine sulfate CR significantly increased ratings of all positive subjective measures relative to placebo (P < 0.0001). Crushed MSN significantly decreased all positive subjective ratings compared with morphine sulfate CR (P ≤ 0.005), but significantly increased ratings compared with placebo (P < 0.03). Peak pupil diameter was significantly larger for MSN than morphine sulfate (P < 0.0001). PK analysis of morphine plasma concentrations indicated that Cmax was significantly lower and tmax significantly longer for crushed MSN compared with crushed morphine sulfate CR. Plasma concentrations of naltrexone and 6-ß-naltrexol were present following crushed MSN. CONCLUSIONS: This study demonstrated that when crushed and administered orally to nondependent recreational opioid users, MSN was associated with significantly lower scores on all positive subjective measures including drug liking and high, and significantly less pupil constriction compared with crushed morphine sulfate CR.

A clinical trial to determine if corelease of morphine and naltrexone from crushed extended-release capsules induces withdrawal in opioid-dependent patients: a descriptive analysis of six patients.

OBJECTIVE: To evaluate whether intact or crushed doses of an extended-release formulation of morphine sulfate surrounding an inner core of sequestered naltrexone (MSN) induces signs and symptoms of withdrawal in opioid-dependent patients. DESIGN: Randomized, double-blind, two-way crossover study. SETTING: Single center. PATIENTS: Fourteen patients with chronic moderate-to-severe noncancer pain receiving opioids were enrolled into the study; six completed the maintenance and treatment phases prior to early study discontinuation for issues with manufacturing; eight discontinued: adverse effects (4), noncompliance (1), patient decision (1), study termination (2). INTERVENTIONS: Patients were titrated to a stable dose of MSN (ranging from 30/1.2 to 100/4.0 mg of morphine/naltrexone) that was used in the single-dose crossover evaluation of crushed and intact MSN. MAIN OUTCOME MEASURES: Clinical Opiate Withdrawal Scale (COWS). RESULTS: Clinically significant withdrawal (COWS ≥ 13) was observed with rapid onset (≤0.8 hours postdose) in three patients (50 percent) following treatment with crushed MSN at the highest doses administered of ≥60/2.4 mg. Although naltrexone exposure was negligible following exposure to intact MSN, increasing plasma levels of naltrexone and 6-ß-naltrexol were associated with COWS score ≥13 in patients who received crushed MSN. COWS ≥ 13 was observed in one patient receiving intact MSN without quantifiable naltrexone concentrations. CONCLUSION: Crushing the MSN capsule may precipitate moderate-to-severe signs and symptoms of opioid withdrawal in opioid-dependent individuals. The negligible exposure to naltrexone following exposure to intact MSN supports that intact capsules may be taken safely without precipitating withdrawal in opioid-dependent individuals.

Effects of concurrent intravenous morphine sulfate and naltrexone hydrochloride on end-tidal carbon dioxide.

BACKGROUND: Respiratory depression, a potentially fatal side-effect of opioid-overdose, may be reversed by timely administration of an opioid antagonist, such as naloxone or naltrexone. Tampering with a formulation of morphine sulfate and sequestered naltrexone hydrochloride extended release capsules (MS-sNT) releases both the opioid morphine and the antagonist naltrexone. A study in recreational opioid-users indicated that morphine and naltrexone injected in the 25:1 ratio (duplicating the ratio of the formulation) found MS-sNT reduced morphine-induced euphoric effects vs intravenous (IV) morphine alone. In the same study, the effects of morphine + naltrexone on end-tidal carbon dioxide (EtCO2), a measure of respiratory-depression, were evaluated and these data are reported here. METHODS: Single-center, placebo-controlled, double-blind crossover study. Non-dependent male opioid users were randomized to receive single IV doses of placebo, 30 mg morphine alone, and 30 mg morphine + 1.2 mg naltrexone. EtCO2 was measured by noninvasive capnography. RESULTS: Significant differences in EtCO2 least-squares means across all treatments for maximal effect (Emax) and area under the effect curve (AUE0-2, AUE0-8, AUE0-24) were detected (all p ≤ 0.0011). EtCO2 Emax values for morphine + naltrexone were significantly reduced vs morphine alone (42.9 mm Hg vs 47.1 mm Hg, p < 0.0001) and were not significantly different vs placebo (41.9 mm Hg). Median time to reach maximal effect (TEmax) was delayed for morphine + naltrexone vs morphine alone (5.0 h vs 1.0 h). CONCLUSIONS: Results provide preliminary evidence that the naltrexone:morphine ratio within MS-sNT is sufficient to significantly reduce EtCO2 when administered intravenously to non-dependent male recreational opioid-users. Further studies with multiple measures of respiratory-function are warranted to determine if risk of respiratory depression is also reduced by naltrexone in the tampered formulation.

Does thalidomide have an analgesic effect? Current status and future directions.

Dramatic relief of pain and life-altering changes in quality of life in some patients treated with immunomodulators such as thalidomide compel us to look more closely at unconventional mechanisms that may be involved in propagation of persistent pain. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and IL-10 are the cytokines with the most evidence in pain modulation. TNF-alpha and IL-1beta seem to initiate neuropathic pain, IL-6 maintains such pain, and IL-10 inhibits this persistent pain. Thalidomide was found to be effective in animal models by inhibiting TNF-alpha production. Several case reports and case series in humans have demonstrated mixed results, with some patients having dramatic responses, especially in chronic intractable conditions such as complex regional pain syndrome. Thalidomide may be an alternative for some patients with intractable pain. However, use of thalidomide is limited by its neurotoxic and teratogenic effects. Newer analogues may significantly improve the risk/benefit of using such immunomodulators.

Conflict about expressing emotions and chronic low back pain: associations with pain and anger.

UNLABELLED: There has been growing interest among researchers and clinicians in the role of ambivalence over emotional expression (AEE) in adjustment to chronic illness. Because of the salience of anger in chronic low back pain, this condition provides a particularly good model in which to examine the role of AEE. This study examined the relation of AEE to pain and anger in a sample of 61 patients with chronic low back pain. Patients completed standardized measures of AEE, pain, and anger. Correlational analyses showed that patients who had higher AEE scores reported higher levels of evaluative and affective pain as well as higher levels of state and trait anger and the tendency to hold in angry thoughts and feelings. Mediational analyses revealed that most of the associations between AEE and pain, and AEE and anger, were independent of one another. These findings suggest that a potentially important relationship exists between AEE and key aspects of living with persistent pain. PERSPECTIVE: This preliminary study suggests that there is a relation between ambivalence over emotional expression and pain and anger in patients with chronic low back pain. Patients who report greater conflict with regard to expressing emotions may be experiencing higher pain and anger.

Loving-kindness meditation for chronic low back pain: results from a pilot trial.

PURPOSE: Loving-kindness meditation has been used for centuries in the Buddhist tradition to develop love and transform anger into compassion. This pilot study tested an 8-week loving-kindness program for chronic low back pain patients. METHOD: Patients (N = 43) were randomly assigned to the intervention or standard care. Standardized measures assessed patients' pain, anger, and psychological distress. FINDINGS: Post and follow-up analyses showed significant improvements in pain and psychological distress in the loving-kindness group, but no changes in the usual care group. Multilevel analyses of daily data showed that more loving-kindness practice on a given day was related to lower pain that day and lower anger the next day. CONCLUSIONS: Preliminary results suggest that the loving-kindness program can be beneficial in reducing pain, anger, and psychological distress in patients with persistent low back pain. IMPLICATIONS: Clinicians may find loving-kindness meditation helpful in the treatment of patients with persistent pain.

Forgiveness and chronic low back pain: a preliminary study examining the relationship of forgiveness to pain, anger, and psychological distress.

UNLABELLED: Clinical observations suggest that many patients with chronic pain have difficulty forgiving persons they perceive as having unjustly offended them in some way. By using a sample of 61 patients with chronic low back pain, this study sought to determine the reliability and variability of forgiveness assessments in patients and to examine the relationship of forgiveness to pain, anger, and psychological distress. Standardized measures were used to assess patients' current levels of forgiveness, forgiveness self-efficacy, pain, anger, and psychological distress. Results showed that forgiveness-related constructs can be reliably assessed in patients with persistent pain, and that patients vary considerably along dimensions of forgiveness. Furthermore, correlational analyses showed that patients who had higher scores on forgiveness-related variables reported lower levels of pain, anger, and psychological distress. Additional analyses indicated that state anger largely mediated the association between forgiveness and psychological distress, as well as some of the associations between forgiveness and pain. These findings indicate that forgiveness can be reliably assessed in patients with persistent pain, and that a relationship appears to exist between forgiveness and important aspects of living with persistent pain. PERSPECTIVE: This preliminary study suggests there is a relationship between forgiveness and pain, anger, and psychological distress in patients with chronic low back pain. Patients who report an inability to forgive others might be experiencing higher pain and psychological distress that are mediated by relatively higher levels of state anger.