Background and Aims: The opioid epidemic has become increasingly concerning, with the ever-increasing prescribing of opioid medications in recent years, especially in inflammatory bowel disease [IBD] patients with chronic pain. We aimed to isolate the effect of opioid use disorder [OUD] on 30-day readmission risk after an IBD-related hospitalization. Methods: We retrospectively extracted IBD-related adult hospitalizations and 30-day, any-cause, readmissions from the National Readmissions Database [period 2010-2014]. OUD and 30-day readmission trends were calculated. Conventional and exact-matched [EM] logistic regression and time-to-event analyses were conducted among patients who did not undergo surgery during the index hospitalization, to estimate the effect of OUD on 30-day readmission risk. Results: In total, 487 728 cases were identified: 6633 [1.4%] had documented OUD And 308 845 patients [63.3%] had Crohn's disease. Mean age was 44.8 ± 0.1 years, and 54.3% were women. Overall, 30-day readmission rate was 19.4% [n = 94,546], being higher in OUD patients [32.6% vs 19.2%; p < 0.001]. OUD cases have been increasing [1.1% to 1.7%; p-trend < 0.001], while 30-day readmission rates were stable [p-trend = 0.191]. In time-to-event EM analysis, OUD patients were 47% more likely (hazard ratio 1.47; 95% confidence interval [CI]:1.28-1.69; p < 0.001) to be readmitted, on average being readmitted 32% earlier [time ratio 0.68; 95% CI: 0.59-0.78; p < 0.001]. Conclusion: OUD prevalence has been increasing in hospitalized IBD patients from 2010 to 2014. On average, one in five patients will be readmitted within 30 days, with up to one in three among the OUD subgroup. OUD is significantly associated with increased 30-day readmission risk in IBD patients and further measures relating to closer post-discharge outpatient follow-up and pain management should be considered to minimize 30-day readmission risk.

Background: The consequences of continued opioid abuse among patients treated with opioid substitution therapy (OST) are serious and can result in abnormal cardiovascular function, overdose, and mortality. Conflicting evidence exists that both implicates and refutes the role of chronic non-cancer pain (CNCP) as a major risk factor for continued opioid abuse within the addiction treatment setting. This thesis aims to 1) evaluate the impact of chronic pain on the treatment outcomes of patients with opioid addiction receiving OST, 2) determine whether a clinical or inflammatory profile exists to distinguish pain in this population, 3) explore the sources of heterogeneity in previous studies examining this question, 4) determine the best therapy for patients with chronic pain, and 5) evaluate the most effective treatment for opioid addiction. We anticipate chronic pain to be an important predictor of continued opioid abuse such that patients with comorbid pain will require careful consideration when managed on OST. Methods: We systematically reviewed the literature to determine the impact of pain in opioid addiction patients receiving methadone maintenance treatment (MMT). We determined the clinical and inflammatory profile of MMT patients using data from the Genetics of Opioid Addiction (GENOA) research collaborative between the Canadian Addiction Treatment Centres (CATC) and the Population Genomic Program. GENOA is a prospective cohort study aimed to determine the genetic, biological, and psychosocial determinants of treatment prognosis for opioid addiction patients receiving MMT. GENOA recruits patients ≥ 18 years of age meeting the DSM-IV criteria for opioid dependence. All GENOA participants are receiving MMT for the management of opioid addiction. Baseline data from the GENOA pilot study (n=235) were used to evaluate the impact of pain on illict opioid use behaviour and determine the clinical and inflammatory profile of patients with comorbid pain. We explored sources of heterogeneity in previous studies using data from the full-phase GENOA study (n=444), examining the prognostic value of different pain measures for predicting illicit opioid use. We then performed a multiple treatment comparison of all opioid substitution and antagonist therapies in efforts to determine the best intervention for improving treatment outcomes for patients with comorbid pain. We lastly determined the most effective treatment for opioid addiction by performing a network meta-analysis using data from a systematic review of opioid maintenance therapy trials. Results: Our initial systematic review confirmed a lack of consensus in the literature, whereby some studies suggest pain increases risk for illicit opioid use and other studies suggest pain has no effect on substance use behaviour. Findings from the analysis of GENOA pilot data confirmed chronic pain to be an important predictor of sustained opioid abuse and also showed patients with pain to have elevated Interferon-Gamma. Using data from the GENOA prospective cohort study we determined the Brief Pain Inventory (a commonly used pain measurement in pervious studies) to be highly sensitive with poor prognostic value. Our final reviews propose 1) there is limited evidence to suggest any OST is superior for managing patients with comorbid pain, and 2) heroin and high-dose methadone are the most effective treatments for improving treatment retention. The final systematic review and network meta-analysis in this thesis also highlights a major problem in the treatment of opioid use disorders, primarily the lack of consensus as to what outcomes matter for determining success in patients with addiction. Conclusion: Patients with comorbid pain and addiction are at high-risk for continued opioid abuse and should be managed closely by clinicians administering OST. Contention in the previous literature likely resulted from the use of pain measurements with poor prognostic value. No OST demonstrated superiority for managing patients with chronic pain. While our findings indicate heroin is the most effective treatment across multiple endpoints, we use this thesis to provide readers with 1) a sense of the feasibility issues associated with heroin administration, 2) a summary of the limitations of this evidence base, and 3) recommendations for how to improve the addiction trials’ design for future research. / Thesis / Doctor of Philosophy (PhD)

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京都大学 / 新制・課程博士 / 博士(医学) / 甲第25489号 / 医博第5089号 / 新制||医||1073(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 林 康紀, 教授 岩田 想, 教授 寺田 智祐 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Opioids are used routinely in the pediatric intensive care population for analgesia, sedation, blunting of physiologic responses to stress, and safety. In children, physical dependence may occur in as little as two to three days of continuous opioid therapy. Once the child no longer needs the opioid, the medications are reduced over time. A review of the literature revealed that the majority of the published studies used either a neonatal opioid assessment tool or no assessment tool. A subsequent international survey of pediatric providers found a wide range of opioid tapering practices and sporadic use of opioid withdrawal instruments to guide practice. Since tapering routines vary among practitioners, it is not uncommon to see signs and symptoms of opioid withdrawal. A prospective, descriptive study was conducted to describe the frequency of opioid withdrawal signs and symptoms and to identify factors associated with these opioid withdrawal signs and symptoms. The sample of 25 was drawn from all patients, ages 2 weeks to 21 years admitted to the Children’s Hospital of Richmond Pediatric Intensive Care Unit (PICU) and who have received continuous infusion or scheduled opioids for at least 5 days. Data collected included: opioid withdrawal score (WAT-1), opioid taper rate (total dose of opioid per day in morphine equivalents per kilogram [MEK]), pretaper peak MEK, pretaper cumulative MEK, number of days of opioid exposure prior to taper, and age. Out of 26 enrolled participants, only 9 (45%) had opioid withdrawal on any given day. In addition, there was limited variability in WAT-1 scores. The most common symptoms notes were diarrhea, vomit, sweat, and fever. For optimal opioid withdrawal assessments, clinicians should use a validated instrument such as the WAT-1 to measure for signs and symptoms of opioid withdrawal. Further research is indicated to examine risk factors for opioid withdrawal in children.

Most clinical opioids produce analgesia through the Mu Opioid Receptor (MOR) providing the only effective treatment for chronic pain patients. These studies explore three pre-clinical strategies to improve MOR analgesia and minimize side effects: 1) compounds that target G-protein Coupled Receptors (GPCRs) heterodimers, such as heterodimerization between the Delta Opioid Receptor (DOR) and MOR (MDOR); 2) multi-functional compounds that target multiple receptor systems for synergistic effects, such as a MOR agonist and a the serotonin reuptake transporter (SERT) inhibitor; or 3) biased agonists that preferentially activate one signaling pathway associated with analgesia over another associated with side effects at the same receptor. First, several indirect lines of evidence indicate the MOR-DOR heterodimer (MDOR) can regulate MOR opioid tolerance and withdrawal. However, studying MDOR remains difficult because no selective MDOR antagonists are available. To address this need, we created a novel series of bivalent MDOR antagonists by connecting a low affinity MOR antagonist (H-Tyr-Pro-Phe-D1Nal-NH2) to a moderate affinity DOR (H- Tyr-Tic-OH) antagonist with variable length polyamide spacers (15-41 atoms). In vitro radioligand binding and [35S]-GTPγS coupling assays in MOR, DOR, and MDOR expressing cell lines show bivalent ligands produce a clear length dependence in MDOR but not MOR or DOR cell lines. The lead compound – D24M with a 24-atom spacer – displayed high potency (IC50MDOR = 0.84 nM) with 91-fold selectivity for MDOR:DOR and 1,000-fold MDOR:MOR selectivity. Second, clinicians have long appreciated subtle but distinct differences in analgesia and side effects of MOR opioids. A variety of non-MOR targets including DOR, Kappa Opioid Receptor (KOR), the Cannabinoid Receptor-1 (CB1), the Sigma-1 Receptor (σ1R), the Dopamine- (DAT), Serotonin- (SERT) and Norepinephrine- Reuptake Transporters (NET) induce analgesia and/or modulate MOR mediated side effects. To determine if different opioid profiles arise from non-MOR interactions, we evaluated the binding and function of nine clinical analgesics at the nine aforementioned targets revealing several clinical opioids contain previously unidentified affinity’s or activity’s. Hydrocodone displayed low affinity at the MOR (KI = 1800 nM) and only ~2 fold less affinity at the σ1R (KI = 4000 nM). Second buprenorphine promoted monoamine influx at DAT, SERT and NET with EC50 > 1,000 nM. These novel interactions suggest the nuanced differences of clinical opioids may arise from previously unappreciated off-target effects. Future studies will assess whether these in vitro results predict hydrocodone and buprenorphine activity in vivo. Finally, the unique function of the numerous endogenous opioid peptides at a given receptor remains unclear. How endogenous ligands interact with ORs produces obvious drug design consequences. These studies show two endogenous Dynorphin analogues – Dynorphin A and Dynorphin B – differentially regulate two ubiquitous signaling modules – βarrestin2 and Gαi/o– at the DOR. Dynorphin A and Dynorphin B swap potency rank orders for β-arrestin2 recruitment and [35S]-GTPγS signaling, indicating two distinct signaling platforms are formed. Dynorphin A but not Dynorphin B treatment simulated AC super activation, while Dynoprhin B internalized DOR better than Dynorphin A. These in vitro assays suggest endogenous Dynorphin analogues differentially regulate signals at the DOR in vitro. Future work includes further characterizing signaling differences in vitro and testing these changes in vivo.

Opium, the dried resin obtained from the unripe seedpods of the poppy flower, has been used for medicinal and euphoric purposes since ancient times. Morphine, the main active ingredient of opium, and other clinically useful opioid analgesics all mediate their effects through activating the mu opioid receptor. Studies involving the mu opioid receptor knockout mice showed that the interaction with the mu opioid receptor is also responsible for many notorious side effects associated with these drugs including dependence and addiction. Therefore, selective antagonists for the mu opioid receptor are needed to study its function in drug abuse and addiction. Previously, based on molecular modeling studies and the “message-address” concept, a series of 14-O-substituted naltrexone derivatives were designed and synthesized. These compounds carried an ester-linked heteroaromatic substitution at the 14-position of naltrexone which was designed to interact with the putative “address” site, that was identified in the mu opioid receptor through molecular modeling studies. The lead compound of this series was determined to have a high affinity and selectivity for the mu opioid receptor. Because the 14-O-substituted naltrexone derivatives were not very stable, the ester linkage in these compounds was replaced by an amide one and a series of 14-N-substituted naltrexone derivatives were synthesized. The affinity and selectivity of these novel naltrexone derivatives were determined in a competitive radioligand binding assay. Interestingly, the 14-N-substituted naltrexone derivatives did not maintain the high selectivity of the 14-O-substituted series. It was hypothesized that the conformational constraint introduced by the amide linker was detrimental to the mu opioid receptor selectivity. Therefore, three 14-N-substituted naltrexone derivatives which carried more flexible linkages were synthesized and evaluated. The mu opioid receptor selectivity was not recovered by introducing rotational freedom into the linker. Some of these 14-N-substitued naltrexone derivatives were determined to be mu-kappa opioid receptor dual selective antagonists. Since the mu opioid receptor antagonists are effective at treating drug addiction, while growing evidence suggests that the kappa opioid receptor antagonists may be beneficial in lowering drug cravings, these novel mu-kappa opioid receptor dual selective antagonists may find unique clinical utility in the treatment of opioid dependence.

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Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.