Use of a sequential multiple assignment randomized trial to test contingency management and an integrated behavioral economic and mindfulness intervention for buprenorphine-naloxone medication adherence for opioid use disorder.

BACKGROUND: Buprenorphine-naloxone is a medication shown to improve outcomes for individuals seeking treatment for opioid use disorder (OUD); however, outcomes are limited by low medication adherence rates. This is especially true during the early stages of treatment. METHODS: The present study proposes to utilize a sequential multiple assignment randomized trial design to compare two psychological interventions targeting buprenorphine-naloxone adherence: (1) contingency management (CM) and (2) brief motivational interviewing plus substance-free activities session plus mindfulness (BSM). Participants will be N = 280 adults who present to a university-based addictions clinic seeking treatment for OUD. Participants will be randomized to condition to receive 4 sessions of their assigned intervention (CM or BSM). Participants who are adherent, defined as attending physician appointments and having buprenorphine present in urine toxicology, will enter maintenance intervention for an additional 6 months. Those who are not adherent will be re-randomized to receive either the other intervention or both interventions. Follow-up will occur at 8 months post-randomization. CONCLUSIONS: This novel design will examine the benefit of sequential treatment decisions following non-adherence. The primary outcome of this study is buprenorphine-naloxone medication adherence, as assessed by physician visit attendance and presence of buprenorphine in urine. Results will elicit the relative efficacy of CM and BSM compared to one another and whether keeping the initial treatment approach when adding the alternative approach for initially non-adherent individuals is beneficial. TRIAL REGISTRATION: ClinicalTrials.gov NCT04080180.

What's new in atopic eczema? An analysis of systematic reviews published in 2018. Part 2: systemic therapies.

This review forms part of an annual update series on atopic eczema (AE), where systematic reviews (SRs) are gathered and appraised to provide a summary of key recent research findings. The focus of this article is systemic therapies used in AE, while a review on prevention and topical therapies is provided in Part 1. In total, 17 SRs on various systemic treatments used in AE were first published or indexed in 2018. There is a lack of evidence to support vitamin D supplementation, montelukast and naltrexone in AE treatment. The adverse effects of systemic corticosteroids are the main barrier to their use, and there is also a lack of data to determine the optimal delivery and duration of treatment with them. Of other immunosuppressants, ciclosporin has the most robust evidence of efficacy. Biologic therapies in AE treatment are being increasingly investigated, and to date, the greatest quantity of data and evidence of efficacy relates to dupilumab. The most commonly reported adverse effects are injection-site reactions and conjunctivitis. Other biologics showing some evidence of efficacy include nemolizumab, lebrikizumab and tralokinumab, although further data are needed. There are currently insufficient data on oral small molecules, including Janus kinase inhibitors, in the treatment of AE. A Cochrane review on probiotics showed no significant benefit, and SRs and meta-analyses on complementary and alternative medicines, including probiotics, in paediatric AE demonstrated significant heterogeneity, thereby limiting their interpretation. This summary of recent SRs provides up-to-date evidence for clinicians on systemic therapies in AE.

Pharmacologic Treatment of Opioid Use Disorder: a Review of Pharmacotherapy, Adjuncts, and Toxicity.

Opioid use disorder continues to be a significant source of morbidity and mortality in the USA and the world. Pharmacologic treatment with methadone and buprenorphine has been shown to be effective at retaining people in treatment programs, decreasing illicit opioid use, decreasing rates of hepatitis B, and reducing all cause and overdose mortality. Unfortunately, barriers exist in accessing these lifesaving medications: users wishing to start buprenorphine therapy require a waivered provider to prescribe the medication, while some states have no methadone clinics. As such, users looking to wean themselves from opioids or treat their opioid dependence will turn to alternative agents. These agents include using prescription medications, like clonidine or gabapentin, off-label, or over the counter drugs, like loperamide, in supratherapeutic doses. This review provides information on the pharmacology and the toxic effects of pharmacologic agents that are used to treat opioid use disorder. The xenobiotics reviewed in depth include buprenorphine, clonidine, kratom, loperamide, and methadone, with additional information provided on lofexidine, akuamma seeds, kava, and gabapentin.

Role of Xingnaojing combined with naloxone in treating intracerebral haemorrhage: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Xingnaojing injection (XNJ) sharpen the mind and induce consciousness and are widely used in acute phases of intracerebral hemorrhage (ICH). Naloxone hydrochloride injection (NX) performs equally well and replace the effects of morphine-like substances to promote conscious awareness. The applications of XNJ combined with NX for ICH show some advantages compared with NX applied individually. The aim of this systematic review is to evaluate the effectiveness and safety of XNJ combined with NX for ICH. METHODS: Comprehensive searches were conducted in 8 medical databases (PubMed, Cochrane Library, Web of Science, Embase, CNKI, VIP, CBM and Wanfang database) from inceptions to October 2017 for randomized controlled trials (RCTs) that compared the applications of XNJ and NX with NX applied individually in ICH. Literature screening, assessing risk of bias and data extraction were conducted by 2 reviewers independently. According to the Cochrane Collaboration's RevMan5.3 software to perform the data analysis. RESULTS: 32 RCTs (3068 cases) were selected and the quality of studies were low. All trials compared XNJ and NX with NX applied individually. The overall meta-analysis results showed that XNJ combined with NX have significant effect on clinical efficacy (OR 3.78, 95% CI: 3.03-4.73; P < .00001), GCS score (MD 3.86, 95% CI: 3.46-4.25; P < .00001), coma duration (MD -5.59, 95% CI: -6.96 to -4.22; P < .00001), NIHSS score (MD -6.24, 95% CI: -8.05 to -4.42; P < .00001), Barthel Index score (MD 14.12, 95% CI: 6.7-21.54; P < .0002), cerebral hematoma volume (MD -6.05, 95% CI: -6.85 to -5.24; P < .00001) than NX applied individually. Adverse events reported in 4 studies and included mild discomfort symptoms. CONCLUSION: The effectiveness and safety of XNJ combined with NX for ICH cannot be determined due to the low quality of literature, publication bias and heterogeneity. More rigorous RCTs are necessary to verify the role of XNJ combined with NX in the treatment of ICH.

A Review on the Antinociceptive Effects of Mitragyna speciosa and Its Derivatives on Animal Model.

Mitragyna speciosa is a tropical plant with narcotic effects. The antinociceptive effects of its crude extracts, bioactive compounds and structurally modified derivatives have been examined in rodent models. This review aims to summarize the evidence on the antinociceptive effects of M. speciosa and its derivatives and explore whether they can offer an alternative to morphine in pain management. Methanolic and alkaloid extracts of M. speciosa were shown to attenuate the nociceptive response in rodents. Mitragynine and 7-hydroxymitragynine offered better antinociceptive effects than crude extracts. Structurally modified derivatives of 7-hydroxymitragynine, such as MGM-9, MGM- 15, MGM-16, demonstrated superior antinociceptive effects compared to morphine. M. speciosa and its derivatives mainly act on the opioid receptor, but receptor subtypes specificity differs between each compound. The tolerance and adverse side effects of M. speciosa and its derivatives are similar with morphine. The affinity of MGM-9 on kappa-opioid receptor could potentially limit the effects of drug dependence. In conclusion, M speciosa derivatives can offer alternatives to morphine in controlling chronic pain. Structural modification of mitragynine and 7-hydroxymitragynine can generate compounds with higher potency and lesser side-effects. Human clinical trials are required to validate the use of these compounds in clinical setting.

Low-Dose Naltrexone Treatment of Familial Benign Pemphigus (Hailey-Hailey Disease).

Importance: Familial benign pemphigus, or Hailey-Hailey disease (HHD), is a rare and debilitating genetic dermatosis characterized by chronic, recurrent vesicles, erosions, and maceration in flexural areas. Despite the reported therapeutic modalities, such as topical and systemic corticosteroids, systemic immunomodulators, topical and systemic retinoids, and laser, HHD can still be markedly difficult to control. Objective: To assess low-dose naltrexone hydrochloride in the treatment of recalcitrant HHD. Design, Setting, and Participants: In this case series, 3 patients with biopsy-proven recalcitrant HHD were evaluated in the outpatient dermatology clinic at the Cleveland Clinic. Each patient was treated with low-dose naltrexone hydrochloride at a dosage of 1.5 to 3.0 mg per day. No laboratory monitoring was necessary. Clinical response (healing of erosions, improvement in erythema, and alleviation of pain), adverse effects, and subjective quality of life were monitored throughout the treatment. The study dates were January 2016 to January 2017. Main Outcomes and Measures: Objective clinical response as assessed by the treating dermatologist, subjective quality of life as reported by the patient, and recorded adverse effects were monitored throughout the treatment at intervals of 2 to 3 months. Results: The 3 patients included a woman in her 40s and 2 men in their 60s. Each patient exhibited at least an 80% improvement in extent of disease, with one patient demonstrating 90% clearance. All 3 patients had substantial improvement in quality of life, with one patient reporting improvement in his depression. No adverse effects were recorded. Conclusions and Relevance: Low-dose naltrexone may represent a low-cost and low-risk alternative or adjunct in the treatment of HHD.

Naltrexone for treatment of impaired awareness of hypoglycemia in type 1 diabetes: A randomized clinical trial.

AIMS: Impaired awareness of hypoglycemia (IAH) is a limiting factor in the treatment of type 1 diabetes (T1D) and is a challenging condition to reverse. The objective of this study was to test the hypothesis that naltrexone therapy in subjects with T1D and IAH will improve counterregulatory hormone response and recognition of hypoglycemia symptoms during hypoglycemia. METHODS: We performed a pilot randomized double blind trial of 4weeks of naltrexone therapy (n=10) or placebo (n=12) given orally in subjects with T1D and IAH. Outcome measures included hypoglycemia symptom scores, counterregulatory hormone levels and thalamic activation as measured by cerebral blood flow using MRI during experimental hypoglycemia in all subjects before and after 4weeks of intervention. RESULTS: After 4weeks of therapy with naltrexone or placebo, no significant differences in response to hypoglycemia were seen in any outcomes of interest within each group. CONCLUSIONS: In this small study, short-term treatment with naltrexone did not improve recognition of hypoglycemia symptoms or counterregulatory hormone response during experimental hypoglycemia in subjects with T1D and IAH. Whether this lack of effect is related to the small sample size or due to the dose, the advanced stage of study population or the drug itself should be the subject of future investigation.

Acute responses to opioidergic blockade as a biomarker of hedonic eating among obese women enrolled in a mindfulness-based weight loss intervention trial.

There are currently no commonly used or easily accessible 'biomarkers' of hedonic eating. Physiologic responses to acute opioidergic blockade, indexed by cortisol changes and nausea, may represent indirect functional measures of opioid-mediated hedonic eating drive and predict weight loss following a mindfulness-based intervention for stress eating. In the current study, we tested whether cortisol and nausea responses induced by oral ingestion of an opioidergic antagonist (naltrexone) correlated with weight and self-report measures of hedonic eating and predicted changes in these measures following a mindfulness-based weight loss intervention. Obese women (N = 88; age = 46.7 ± 13.2 years; BMI = 35.8 ± 3.8) elected to complete an optional sub-study prior to a 5.5-month weight loss intervention with or without mindfulness training. On two separate days, participants ingested naltrexone and placebo pills, collected saliva samples, and reported nausea levels. Supporting previous findings, naltrexone-induced cortisol increases were associated with greater hedonic eating (greater food addiction symptoms and reward-driven eating) and less mindful eating. Among participants with larger cortisol increases (+1 SD above mean), mindfulness participants (relative to control participants) reported greater reductions in food addiction symptoms, b = -0.95, SE(b) = 0.40, 95% CI [-1.74, -0.15], p = .021. Naltrexone-induced nausea was marginally associated with reward-based eating. Among participants who endorsed naltrexone-induced nausea (n = 38), mindfulness participants (relative to control participants) reported greater reductions in food addiction symptoms, b = -1.00, 95% CI [-1.85, -0.77], p = .024, and trended toward reduced reward-based eating, binge eating, and weight, post-intervention. Single assessments of naltrexone-induced cortisol increases and nausea responses may be useful time- and cost-effective biological markers to identify obese individuals with greater opioid-mediated hedonic eating drive who may benefit from weight loss interventions with adjuvant mindfulness training that targets hedonic eating.

Naltrexone Maintenance Decreases Cannabis Self-Administration and Subjective Effects in Daily Cannabis Smokers.

Given that cannabis use is increasing in the United States, pharmacological treatment options to treat cannabis use disorder are needed. Opioid antagonists modulate cannabinoid effects and may offer a potential approach to reducing cannabis use. In this double-blind, placebo-controlled human laboratory study, we assessed the effects of naltrexone maintenance on the reinforcing, subjective, psychomotor, and cardiovascular effects of active and inactive cannabis. Nontreatment-seeking, daily cannabis smokers were randomized to receive naltrexone (50 mg: n=18 M and 5 F) or placebo (0 mg; n=26 M and 2 F) capsules for 16 days. Before, during, and after medication maintenance, participants completed 10 laboratory sessions over 4-6 weeks, assessing cannabis' behavioral and cardiovascular effects. Medication compliance was verified by observed capsule administration, plasma naltrexone, and urinary riboflavin. Relative to placebo, maintenance on naltrexone significantly reduced both active cannabis self-administration and its positive subjective effects ('good effect'). Participants in the placebo group had 7.6 times (95% CI: 1.1-51.8) the odds of self-administering active cannabis compared with the naltrexone group. This attenuation of reinforcing and positive subjective effects also influenced cannabis use in the natural ecology. Naltrexone had intrinsic effects: decreasing ratings of friendliness, food intake, and systolic blood pressure, and increasing spontaneous reports of stomach upset and headache, yet dropout rates were comparable between groups. In summary, we show for the first time that maintenance on naltrexone decreased cannabis self-administration and ratings of 'good effect' in nontreatment-seeking daily cannabis smokers. Clinical studies in patients motivated to reduce their cannabis use are warranted to evaluate naltrexone's efficacy as a treatment for cannabis use disorder.

Difference of the naltrexone's effects in social drinkers by spicy food preference.

The purpose of this study was to investigate the differences in subjective acute effects of alcohol and naltrexone among those who prefer spicy food to varying degrees. Acute biphasic alcohol effects scale (BAES), visual analogue scale for craving (VAS-C), blood alcohol concentration (BAC) and food preference scale were measured in 26 men. Repeated measures ANOVA (2 preference groups×4 time blocks) on the stimulative subscale of BAES revealed a significant group by block interaction in naltrexone condition (N+) (P<0.001), but not in non-naltrexone condition (N-). Furthermore, repeated measures ANOVA (2 drug groups×4 time blocks) on the stimulative subscale of BAES revealed a significant group by block interaction in strong preference for spicy food (SP) (P<0.001), but not in lesser preference for spicy food (LP). The paired t-test revealed that significant suppression of the stimulative subscale of BAES was observed at 15 min (P<0.001) and 30 min (P<0.001) after drinking when N+ compared with N- in SP. For those who prefer spicy food, the stimulative effect of acute alcohol administration was suppressed by naltrexone. This result suggests that the effect of naltrexone may vary according to spicy food preference.

Hospitalist management of vaso-occlusive pain crisis in patients with sickle cell disease using a pathway of care.

BACKGROUND: Patients with sickle cell disease (SCD) suffer from intermittent vaso-occlusive pain crises (VOCs). These crises lead to frequent hospitalizations, significant morbidity, and increased mortality risk. Care pathways can enhance efficiency and quality of care. Our study sought to evaluate the development and implementation of a care pathway for patients with SCD experiencing VOCs. METHODS: The University of North Carolina (UNC) Comprehensive Sickle Cell Program provides all levels of care for a large population of patients with sickle cell anemia. All patients admitted to UNC Hospitals with SCD VOCs from January 2009 through June 2011 were evaluated. During this time period, we also assessed sequential prospective cohorts during progressive phases of developing and implementing a quality improvement and pathway of care program for this patient population in our study. The developed pathway entailed geographic localization for VOC patients, a single group of faculty physicians caring for these patients, and early use of patient-controlled analgesia (PCA) to achieve pain control. Physicians from the UNC Hospital Medicine Program were responsible for the initiatives. Cohorts were compared to a baseline historical control. Outcomes of interest included patient length of stay (LOS) in the hospital, 30-day readmission rate, need for transfusion, incidence of acute chest syndrome, use of naloxone, and use of PCA. RESULTS: Compared with an historical baseline cohort, the development and implementation of a VOC care pathway for patients with SCD led to reduction in average hospital LOS by 1.44 days (P < 0.05) and an increase in use of PCAs (P < 0.05). Patient readmission rates, number of transfusions, incidence of acute chest syndrome, and use of naloxone did not significantly change. CONCLUSIONS: Hospitalist-led management of patients with SCD VOCs using a care pathway that emphasizes early, aggressive PCA-based pain control is associated with reduced hospital LOS. The LOS reduction seen in our study is clinically meaningful. Notably, other measures of patient outcomes and quality of care metrics did not change significantly, and some trended towards improvement.

Constipation in palliative care: treatment options and considerations for individual patient management.

Constipation is an all too common symptom in palliative care patients and may be associated with a range of severe issues and experiences. Its effects on patients contribute to both physical and psychological scarring during a very distressing stage of life not only for the patient but also for their caregivers. It is during this time that, too often, the complexity of managing the condition moves the locus of control away from the patient toward the health professionals. This article considers a number of different treatment options and facets of individual management that may enable patients to move the locus of control back to a position of joint management by patients, caregivers, and health professionals.

Pain as a reward: changing the meaning of pain from negative to positive co-activates opioid and cannabinoid systems.

Pain is a negative emotional experience that is modulated by a variety of psychological factors through different inhibitory systems. For example, endogenous opioids and cannabinoids have been found to be involved in stress and placebo analgesia. Here we show that when the meaning of the pain experience is changed from negative to positive through verbal suggestions, the opioid and cannabinoid systems are co-activated and these, in turn, increase pain tolerance. We induced ischemic arm pain in healthy volunteers, who had to tolerate the pain as long as possible. One group was informed about the aversive nature of the task, as done in any pain study. Conversely, a second group was told that the ischemia would be beneficial to the muscles, thus emphasizing the usefulness of the pain endurance task. We found that in the second group pain tolerance was significantly higher compared to the first one, and that this effect was partially blocked by the opioid antagonist naltrexone alone and by the cannabinoid antagonist rimonabant alone. However, the combined administration of naltrexone and rimonabant antagonized the increased tolerance completely. Our results indicate that a positive approach to pain reduces the global pain experience through the co-activation of the opioid and cannabinoid systems. These findings may have a profound impact on clinical practice. For example, postoperative pain, which means healing, can be perceived as less unpleasant than cancer pain, which means death. Therefore, the behavioral and/or pharmacological manipulation of the meaning of pain can represent an effective approach to pain management.

Use of conventional, complementary, and alternative treatments for pain among individuals seeking primary care treatment with buprenorphine-naloxone.

UNLABELLED: Previous studies have not examined patterns of pain treatment use among patients seeking office-based buprenorphine-naloxone treatment (BNT) for opioid dependence. OBJECTIVES: To examine, among individuals with pain seeking BNT for opioid dependence, the use of pain treatment modalities, perceived efficacy of prior pain treatment, and interest in pursuing pain treatment while in BNT. METHODS: A total of 244 patients seeking office-based BNT for opioid dependence completed measures of demographics, pain status (ie, "chronic pain (CP)" [pain lasting at least 3 months] vs "some pain (SP)" [pain in the past week not meeting the duration criteria for chronic pain]), pain treatment use, perceived efficacy of prior pain treatment, and interest in receiving pain treatment while in BNT. RESULTS: In comparison with the SP group (N = 87), the CP group (N = 88) was more likely to report past-week medical use of opioid medication (adjusted odds ratio [AOR] = 3.2; 95% CI, 1.2-8.4), lifetime medical use of nonopioid prescribed medication (AOR = 2.2; 95% CI, 1.1-4.7), and lifetime use of prayer (AOR = 2.8; 95% CI, 1.2-6.5) and was less likely to report lifetime use of yoga (AOR = 0.2; 95% CI, 0.1-0.7) to treat pain. Although the 2 pain groups did not differ on levels of perceived efficacy of prior lifetime pain treatments, in comparison with the SP group, the CP group was more likely to report interest in receiving pain treatment while in BNT (P < 0.001). CONCLUSIONS: Individuals with pain seeking BNT for opioid dependence report a wide range of conventional, complementary, and alternative pain-related treatments and are interested (especially those with CP) in receiving pain management services along with BNT.

[Is the pharmacological treatment of constipation in palliative care evidence based? : a systematic literature review]. / Ist die pharmakologische therapie der obstipation in der palliativmedizin evidenzbasiert? : eine systematische Literaturübersicht.

MATERIALS AND METHODS: To evaluate the evidence for clinically established pharmacological therapies for constipation in palliative care, a systematic literature review was performed in different databases (Cochrane Library, Embase, PubMed, Ovid MEDLINE, CINAHL), textbooks, and publications. RESULTS: Whereas 130 randomized controlled trials were found with patients outside of palliative care settings, only 10 controlled studies with patients in end-of-life situations were identified: three RCTs with methylnaltrexone and one with the combination of oxycodone and naloxone showed the effect and safety of opiate antagonists for patients who are not at risk of gastrointestinal perforation. There have been no studies which test methylnaltrexone against the optimization of therapy with conventional laxatives. Six other controlled studies of limited quality in design and execution and with only few participants tested naloxone, senna, lactulose, Co-danthramer, an Ayurvedic preparation (Misrakasneham), magnesium hydroxide, fluid paraffin, sodium picosulfate and docusate without finding statistically significant differences in efficacy or side effects. Most patients in these studies had cancer. Only case studies with few patients in palliative care were found for meglumine, neostigmine, and other substances mentioned above. CONCLUSION: Evidence on medical treatment of constipation in palliative care is sparse and guidelines have to refer to evidence from outside the palliative care setting and to expert opinions. Results from studies with other patient groups can only be transferred with limitations to very ill patients at the end of life who might have a higher risk for potential side effects such as gastrointestinal perforation in case of abdominal tumor manifestation. Therefore further studies are required to evaluate the medical treatment of multiple reasons for constipation in these patients. These studies should focus on feasibility, clinical relevance and quality of life. The English full text version of this article will be available in SpringerLink as of November 2012 (under "Supplemental").

Mandatory naltrexone treatment prevents relapse among opiate-dependent anesthesiologists returning to practice.

OBJECTIVE: Anesthesiologists with opioid use disorders are at high risk for relapse. In 2005, the impaired professionals monitoring program of the State of Florida implemented a policy whereby anesthesiologists referred for opiate use disorders were contractually obligated to take naltrexone for 2 years. Naltrexone ingestion was witnessed and verified via random urine drugs screens or administered via intramuscular injection. METHOD: Charts were reviewed for the 11 anesthesiologists who underwent mandated pharmacotherapy with naltrexone, and 11 anesthesiologists who began monitoring immediately before implementation of this policy. RESULTS: Eight of 11 anesthesiologists who did not take naltrexone experienced a relapse on opiates. Only 1 of 11 anesthesiologists experienced a relapse on opiates after taking naltrexone, whereas another relapsed on an inhalant (nitrous oxide). It is noteworthy that 5 of the 11 anesthesiologists who took naltrexone had relapsed before naltrexone treatment, and 7 of the 11 anesthesiologists who did not take naltrexone experienced multiple documented relapses. Only 1 of the 11 anesthesiologists who did not take naltrexone successfully returned to the practice of anesthesiology. This individual suffered primarily from alcohol dependence, and suspected opiate abuse was never verified. Others who attempted return to anesthesiology (n = 7) suffered a relapse. In comparison, 9 of the 11 anesthesiologists who took naltrexone have returned to the practice of anesthesiology without a relapse (as verified by continued random urine and hair testing). CONCLUSION: Mandatory naltrexone treatment may provide anesthesiologists with an additional safeguard to successfully return to work.

Effect of acupuncture on naloxone-precipitated withdrawal syndrome in morphine-experienced rats: the mediation of GABA receptors.

Repeated morphine administration increases extracellular dopamine levels in the nucleus accumbens, which results in behavioral sensitization that can be suppressed by acupuncture at Shenmen (HT7) points. The present study was conducted to investigate the effects of acupuncture at HT7 on morphine withdrawal syndrome as well as to explore the role of GABA receptors in mediating the effects of HT7 acupuncture. We induced morphine withdrawal by injecting naloxone to rats that self-administer morphine and evaluated the effects of acupuncture and/or GABA receptor antagonists on their withdrawal symptoms. Acupuncture at HT7, but not at the control point LI5, significantly decreased symptoms of morphine withdrawal. HT7 inhibition of the withdrawal syndrome was blocked by pretreatment with either the GABA(A) receptor antagonist bicuculline or the GABA(B) antagonist SCH 50911. These findings suggest that the effects of acupuncture on suppression of morphine withdrawal syndrome are mediated, at least in part, through GABA receptors.

N-naphthoyl-beta-naltrexamine (NNTA), a highly selective and potent activator of µ/kappa-opioid heteromers.

Numerous G protein-coupled receptors (GPCRs) have been shown to form heteromeric receptors in cell-based assays. Among the many heteromers reported in the opioid receptor family are µ/κ, κ/δ, and µ/δ. However, the in vivo physiological and behavioral relevance for the proposed heteromers have not yet been established. Here we report a unique example of a ligand, N-naphthoyl-ß-naltrexamine (NNTA) that selectively activates heteromeric µ/κ-opioid receptors in HEK-293 cells and induces potent antinociception in mice. NNTA was an exceptionally potent agonist in cells expressing µ/κ-opioid receptors. Intriguingly, it was found to be a potent antagonist in cells expressing only µ-receptors. In the mouse tail-flick assay, intrathecal (i.t.) NNTA produced antinociception that was ~100-fold greater than by intracerebroventricular (i.c.v.) administration. The κ-antagonist, norBNI, decreased the i.t. potency, and the activity was virtually abolished in µ-opioid receptor knockout mice. No tolerance was induced i.t., but marginal tolerance (3-fold) was observed via the i.c.v. route. Moreover, NNTA produced neither significant physical dependence nor place preference in the ED50 dose range. Taken together, this work provides an important pharmacologic tool for investigating the in vivo functional relevance of heteromeric µ/κ-opioid receptors and suggests an approach to potent analgesics with fewer deleterious side effects.

The role of opioid receptor antagonists in the treatment of opioid-induced constipation: a review.

Opioid-induced constipation (OIC) is associated with negative impact of opioid analgesics on opioid receptors located in the gut wall. Until recently, OIC was treated symptomatically only, with different laxatives which did not target the pathophysiology of OIC. Recently, several opioid receptor antagonists have been introduced in the treatment of OIC. Methylnaltrexone (MNTX) is a peripheral mu-opioid receptor antagonist for subcutaneous administration, which does not evoke symptoms of opioid abstinence. MNTX is indicated for patients with OIC who are not amenable to therapy with oral laxatives. In clinical trials, the effectiveness of MNTX assessed as its ability to induce spontaneous bowel movement, is 50%-60% of treated patients; MNTX demonstrates significant superiority over placebo. Another product is combination of oral formulation of prolonged release oxycodone and prolonged release naloxone (PR oxycodone/PR naloxone), indicated for patients who require opioid administration for chronic pain and have already developed OIC, and for those who need opioid therapy and take the drug to prevent OIC. Naloxone administered orally displays local, antagonist effects on opioid receptors in the gut wall, negligible systemic bioavailability, and significantly reduces the oxycodone constipating effect. PR oxycodone/PR naloxone has similar analgesic efficacy, but causes less constipation and less laxative consumption in comparison with patients treated with oxycodone alone. Both products are expensive, therefore their administration should be carefully considered. On the other hand, uncontrolled OIC and the necessity to perform rectal invasive procedures (enema, manual evacuation) lead not only to increased health care costs, but most importantly, cause severe patient suffering.

A prolonged protein kinase C-mediated, opioid-related antinociceptive effect of st John's Wort in mice.

UNLABELLED: The antinociceptive profile of St. John's Wort (SJW) was investigated in mice in a condition of acute thermal and chemical pain, together with the mechanism that might underlie this effect. A dried extract of SJW induced a prolonged antinociception that persisted for 120 minutes after administration. The thermal antinociception was prevented by naloxone and by the protein kinase C (PKC) activator PMA, whereas the chemical antinociception was prevented by PMA, remaining naloxone insensitive. A chloroform (CHL) and a methanol (MET) fraction, obtained to investigate the involvement of the SJW main components, hyperforin and hypericin/flavonoid, respectively, increased pain threshold with a time course comparable to the dried extract. The CHL antinociception was prevented by naloxone, whereas the MET antinociception was antagonized by PMA. Purified hyperforin and hypericin showed an antinociceptive efficacy comparable to CHL and MET, respectively. Conversely, flavonoids were devoid of any effect. The administration of yohimbine and atropine did not modify SJW, CHL and MET antinociception. These results indicate that both CHL and MET fractions mediate the SJW-induced antinociception. In particular, the presence of hypericin was fundamental to induce both thermal and chemical antinociception through the inhibition of the PKC activity, whereas hyperforin selectively produced a thermal opioid antinociception. PERSPECTIVE: This article presents evidence of a persistent thermal and chemical antinociception of SJW that is mainly mediated by PKC-inhibiting mechanisms. These findings identify important targets for a longer-acting activation of endogenous pain systems and should potentially help clinicians who seek safe, tolerable, and prolonged treatments for pain relief.