The impact of opioid analgesics on the gastrointestinal tract function and the current management possibilities

Biasing Gβγ Downstream Signaling with Gallein Inhibits Development of Morphine Tolerance and Potentiates Morphine-Induced Nociception in a Tolerant State

Opioid analgesics are widely used as a treatment option for pain management and relief. However, the misuse of opioid analgesics has contributed to the current opioid epidemic in the United States. Prescribed opioids such as morphine, codeine, oxycodone, and fentanyl are mu-opioid receptor (MOR) agonists primarily used in the clinic to treat pain or during medical procedures, but development of tolerance limits their utility for treatment of chronic pain. Here we explored the effects of biasing Gβγ signaling on tolerance development after chronic morphine treatment in vivo. We hypothesized that biasing Gβγ signaling with gallein could prevent activation of regulatory signaling pathways that result in tolerance to antinociceptive effects of MOR agonists. Gallein has been shown to bind to Gβγ and inhibit interactions of Gβγ with phospholipase-Cβ3 (PLCβ3) or G-protein-coupled receptor kinase 2 (GRK2) but not G-protein inwardly rectifying potassium (GIRK) channels. In mice, morphine-induced antinociception was evaluated in the 55°C warm water tail withdrawal assay. We used two paradigms for gallein treatment: administration during and after three times-daily morphine administration. Our results show that gallein cotreatment during repeated administration of morphine decreased opioid tolerance development and that gallein treatment in an opioid-tolerant state enhanced the potency of morphine. Mechanistically, our data suggest that PLCβ3 is necessary for potentiating effects of gallein in an opioid-tolerant state but not in preventing the development of tolerance. These studies demonstrate that small molecules that target Gβγ signaling could reduce the need for large doses of opioid analgesics to treat pain by producing an opioid-sparing effect. SIGNIFICANCE STATEMENT: Biasing Gβγ signaling prevents tolerance to repeated morphine administration in vivo and potentiates the antinociceptive effects of morphine in an opioid-tolerant state. Mechanistically, phospholipase-Cβ is necessary for potentiating effects of gallein in an opioid-tolerant state but not in preventing the development of tolerance. This study identifies a novel treatment strategy to decrease the development of tolerance to the analgesic effects of mu-opioid receptor agonists, which are necessary to improve pain treatment and decrease the incidence of opioid use disorder.

Opioid analgesics for nociceptive cancer pain: A comprehensive review

Pain is one of the most burdensome symptoms in people with cancer, and opioid analgesics are considered the mainstay of cancer pain management. For this review, the authors evaluated the efficacy and toxicities of opioid analgesics compared with placebo, other opioids, nonopioid analgesics, and nonpharmacologic treatments for background cancer pain (continuous and relatively constant pain present at rest), and breakthrough cancer pain (transient exacerbation of pain despite stable and adequately controlled background pain). They found a paucity of placebo-controlled trials for background cancer pain, although tapentadol or codeine may be more efficacious than placebo (moderate-certainty to low-certainty evidence). Nonsteroidal anti-inflammatory drugs including aspirin, piroxicam, diclofenac, ketorolac, and the antidepressant medicine imipramine, may be at least as efficacious as opioids for moderate-to-severe background cancer pain. For breakthrough cancer pain, oral transmucosal, buccal, sublingual, or intranasal fentanyl preparations were identified as more efficacious than placebo but were more commonly associated with toxicities, including constipation and nausea. Despite being recommended worldwide for the treatment of cancer pain, morphine was generally not superior to other opioids, nor did it have a more favorable toxicity profile. The interpretation of study results, however, was complicated by the heterogeneity in the study populations evaluated. Given the limited quality and quantity of research, there is a need to reappraise the clinical utility of opioids in people with cancer pain, particularly those who are not at the end of life, and to further explore the effects of opioids on immune system function and quality of life in these individuals.

Evaluation of urinary trace element levels in patients with opioid use disorder undergoing methadone treatment in western Iran

The monitoring of essential and toxic elements in patients with Opioid Use Disorder (OUD) undergoing methadone treatment (MT) is important, and there is limited previous research on the urinary levels of these elements in MT patients. Therefore, the present study aimed to analyze certain elements in the context of methadone treatment compared to a healthy group. In this study, patients with opioid use disorder undergoing MT (n = 67) were compared with a healthy group of companions (n = 62) in terms of urinary concentrations of some essential elements (selenium (Se), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), calcium (Ca)) and toxic elements (lead (Pb), cadmium (Cd), arsenic (As), and chromium (Cr)). Urine samples were prepared using the acid digestion method with a mixture of nitric acid and perchloric acid and assessed using the ICP-MS method. Our results showed that the two groups had no significant differences in terms of gender, education level, occupation, and smoking status. Urinary concentrations of Se, Cu, and Fe levels were significantly lower in the MT group compared to the healthy subjects. However, the concentrations of Pb, Cd, As, Mn, Cr, and Ca in the MT group were higher than in the healthy group (p < 0.05). No significant difference was established between the levels of Zn in the two groups (p = 0.232). The results of regression analysis revealed that the differences between the concentration levels of all metals (except Zn) between two groups were still remained significant after adjusting for all variables (p < 0.05). The data obtained in the current study showed lower urinary concentrations of some essential elements and higher levels of some toxic elements in the MT group compared to the healthy subjects. These findings should be incorporated into harm-reduction interventions.

The impact of opioid administration on the incidence of postanaesthetic colic in horses

Effective management of postoperative pain is essential to ensure patient welfare, reduce morbidity and optimize recovery. Opioids are effective in managing moderate to severe pain in horses but concerns over their adverse effects on gastrointestinal (GI) motility and associated increased colic risk limit their widespread use. Studies investigating the impact of systemic opioids on both GI motility and colic incidence in horses have yielded inconclusive outcomes. Therefore, this retrospective study aims to assess the influence of systemic administration of butorphanol, morphine, and methadone on post-anaesthetic colic (PAC) incidence. Horses undergoing general anaesthesia for non-gastrointestinal procedures that were hospitalized for at least 72 h post-anaesthesia were included in this study. Anaesthetised horses were stratified by procedure type into horses undergoing diagnostic imaging without surgical intervention, emergency or elective surgery. In addition, patients were grouped by opioid treatment regime into horses receiving no opioids, intraanaesthetic, short- (<24 h) or long-term (>24 h) postoperative opioids. Administered opioids encompassed butorphanol, morphine and methadone. The number of horses showing signs of colic in the 72 h after anaesthesia was assessed for each group. A total of 782 horses were included, comprising 659 undergoing surgical procedures and 123 undergoing diagnostic imaging. The overall PAC incidence was 15.1%. Notably, horses undergoing diagnostic imaging without surgery had a significantly lower PAC rate of 6.5% compared to those undergoing surgery (16.7%, p = 0.0146). Emergency surgeries had a significantly lower PAC rate of 5.8% compared to elective procedures (18%, p = 0.0113). Of the 782 horses, 740 received intraoperative opioids and 204 postoperative opioids, 102 of which long-term (≥24 h). Neither intraoperative (p = 0.4243) nor short-term postoperative opioids (p = 0.5744) increased PAC rates. Notably, only the long-term (≥24 h) administration of morphine significantly increased PAC incidence to 34% (p = 0.0038). In contrast, long-term butorphanol (5.3% PAC, p = 0.8482) and methadone (18.4% PAC, p = 0.6161) did not affect PAC rates. In summary, extended morphine administration was the only opioid treatment associated with a significantly increased risk of PAC.

Trace element levels: How Substance Use Disorder (SUD) contributes to the alteration of urinary essential and toxic element levels

Increasing illicit drug use is one of the main problems in most countries or societies. Monitoring heavy metals and trace elements in this vulnerable group seems to be necessary. Therefore, we assessed the urinary trace element and toxic metals/metalloids concentrations (Zinc (Zn), Iron (Fe), Copper (Cu), Chromium (Cr), Lead (Pb), Cadmium (Cd), Arsenic (As), Nickel (Ni), and Mercury (Hg)) in opium, tramadol, and cannabis users compared to healthy subjects. In this cross-sectional study, patients with substance use disorder (SUD) (n = 74) were divided into four groups: cannabis, tramadol, opium, and mixed (simultaneous use of more than one of the three studied substances), along with a healthy group (n = 60). Urine samples were prepared by dispersive liquid-liquid microextraction method so that heavy metals/metalloids could be measured by ICP-MS. The mean urinary concentration of Cu (48.15 vs. 25.45; 89.2%, p<0.001), Hg (1.3 vs. 0.10; 1200%, p < 0.001), and Zn (301.95 vs. 210; 43.8%, p < 0.001) was markedly lower among patients with SUD. The mean urinary concentration of other elements including As (1.9 vs. 4.1; 115.8%), Cd (0.1 vs. 1.10; 1000%), Cr (6.80 vs. 11.65; 71.3%), Ni (2.95 vs. 4.95; 67.8%), and Pb (1.5 vs. 7.9; 426.6%) were significantly higher among patients with SUD compared to healthy subjects. When sub-groups were compared, no significant differences were observed between their trace element levels (Kruskal-Wallis test, p > 0.05). This can be an indication that regardless of the type of drug, the levels of trace elements are changed with respect to healthy individuals. Our results showed that illicit drug use causes changes in urinary trace element/heavy metal/metalloid levels and highlights the need for monitoring heavy metals and trace elements in individuals with substance use disorder. Assessment of different elements in biological samples of drug dependents may be useful for implementing new prevention and treatment protocols. In case of changes in their levels, complementary recommendations, attention to diet, and periodic assessment of toxic metal levels within treatment programs will be needed.

Insights into the Current and Possible Future Use of Opioid Antagonists in Relation to Opioid-Induced Constipation and Dysbiosis

Opioid receptor agonists, particularly those that activate µ-opioid receptors (MORs), are essential analgesic agents for acute or chronic mild to severe pain treatment. However, their use has raised concerns including, among others, intestinal dysbiosis. In addition, growing data on constipation-evoked intestinal dysbiosis have been reported. Opioid-induced constipation (OIC) creates an obstacle to continuing treatment with opioid analgesics. When non-opioid therapies fail to overcome the OIC, opioid antagonists with peripheral, fast first-pass metabolism, and gastrointestinal localized effects remain the drug of choice for OIC, which are discussed here. At first glance, their use seems to only be restricted to constipation, however, recent data on OIC-related dysbiosis and its contribution to the appearance of several opioid side effects has garnered a great of attention from researchers. Peripheral MORs have also been considered as a future target for opioid analgesics with limited central side effects. The properties of MOR antagonists counteracting OIC, and with limited influence on central and possibly peripheral MOR-mediated antinociception, will be highlighted. A new concept is also proposed for developing gut-selective MOR antagonists to treat or restore OIC while keeping peripheral antinociception unaffected. The impact of opioid antagonists on OIC in relation to changes in the gut microbiome is included.

Regulation of the Endogenous Opiate Signaling Pathway against Oxidative Stress and Inflammation: A Considerable Approach for Exploring Preclinical Treatment of Parkinson's Disease

INTRODUCTION

Oxidative stress and inflammation are major factors contributing to the progressive death of dopaminergic neurons in Parkinson's disease (PD). Recent studies have demonstrated that morphine's biosynthetic pathway, coupled with nitric oxide (NO) release, is evolutionarily conserved throughout animals and humans. Moreover, dopamine is a key precursor for morphine biosynthesis.

METHOD

The present study evaluated a series of preclinical experiments to evaluate the effects of low-level morphine treatment upon neuro-immune tissues exposed to rotenone and 6-OHDA as models of PD, followed by an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation assay and cell/tissue computer-assisted imaging analyses to assess cell/neuronal viability.

RESULTS

Morphine at normal physiological concentrations (i.e., 10-6 M and 10-7 M) provided neuroprotection, as it significantly inhibited rotenone and 6-OHDA dopaminergic insults; thereby, reducing and/or forestalling cell death in invertebrate ganglia and human nerve cells. To ensure that morphine caused this neuroprotective effect, naloxone, a potent opiate receptor antagonist, was employed and the results showed that it blocked morphine's neuroprotective effects. Additionally, co-incubation of NO synthase inhibitor L-NAME also blocked morphine's neuroprotective effects against rotenone and 6-OHDA insults.

CONCLUSIONS

Taken together, the present preclinical study showed that while morphine can attenuate lipopolysaccharide-induced inflammation and cell death, both naloxone and L-NAME can abolish this effect. Preincubation of morphine precursors (i.e., L-3,4-dihydroxyphenylalanine, reticuline, and trihexyphenidyl [THP] at physiological concentrations) mimics the observed morphine effect. However, high concentrations of THP, a precursor of the morphine biosynthetic pathway, induced cell death, indicating the physiological importance of morphine biosynthesis in neural tissues. Thus, understanding the morphine biosynthetic pathway coupled with a NO signaling mechanism as a molecular target for neuroprotection against oxidative stress and inflammation in other preclinical models of PD is warranted.

Iatrogenic Side Effects of Pain Therapies

Pain regimens, particularly for chronic cancer and noncancer pain, must balance the important analgesic benefits against potential risks. Many effective and frequently used pain control regimens are associated with iatrogenic adverse events. Interventional procedures can be associated with nerve injuries, vascular injuries, trauma to the spinal cord, and epidural abscesses. Although rare, these adverse events are potentially catastrophic. Pharmacologic remedies for pain must also consider potential side effects that can occur even at therapeutic doses of over-the-counter remedies such as paracetamol (acetaminophen) or nonsteroidal anti-inflammatory drugs. Opioids are effective pain relievers but are associated with many side effects, some of which can be treatment limiting. A prevalent and distressing side effect of opioid therapy is constipation. Opioid-induced constipation is caused by binding to opioid receptors in the gastrointestinal system, making conventional laxatives ineffective. Peripherally acting mu-opioid receptor antagonists are a new drug class that offers the benefits of preserving opioid analgesia without side effects in the gastrointestinal system. An important safety concern, particularly among geriatric patients is the increasingly prevalent condition of polypharmacy. Many senior patients take five or more medications, including some that may be contraindicated in geriatric patients, duplicative of other drugs, have potential pharmacokinetic drug-drug interactions, or may not be the optimal choice for the patient's age and condition. Careful assessment of medications in the elderly, including possibly deprescribing with tapering of certain drugs, may be warranted but should be done systematically and under clinical supervision.

Risk of somatic diseases in patients with eating disorders: the role of comorbid substance use disorders

AIMS

Eating disorders (EDs) and substance use disorders (SUDs) often co-occur, and both involve somatic diseases. So far, no study has considered whether comorbid SUDs may impact somatic disease risk in patients with EDs. Therefore, this study aimed to examine the impact of comorbid SUDs on the risk of 11 somatic disease categories in patients with anorexia nervosa (AN), bulimia nervosa (BN) and unspecified eating disorder (USED) compared to matched controls.

METHODS

A retrospective cohort study was conducted using Danish nationwide registries. The study population included 20 759 patients with EDs and 83 036 controls matched on month and year of birth, sex and ethnicity. Hazard ratios (HRs) were calculated to compare the risk of being diagnosed with a somatic disease (within 11 categories defined by the ICD-10) following first ED diagnosis (index date) between ED patients and controls both with and without SUDs (alcohol, cannabis or hard drugs).

RESULTS

The ED cohort and matched controls were followed for 227 538 and 939 628 person-years, respectively. For ED patients with SUDs, the risk pattern for being diagnosed with different somatic diseases (relative to controls without SUDs) varied according to type of ED and SUD [adjusted HRs ranged from 0.95 (99% CI = 0.57; 1.59) to 4.17 (2.68, 6.47)]. The risk estimates observed among ED patients with SUDs were generally higher than those observed among ED patients without SUDs [adjusted HRs ranged from 1.08 (99% CI = 0.95, 1.22) to 2.56 (2.31, 2.84)]. Abuse of alcohol only had a non-synergistic effect on six disease categories in AN patients and five in BN and USED patients. Abuse of cannabis (with/without alcohol) had a non-synergistic effect on five disease categories in AN and BN patients and two in USED patients. Abuse of hard drugs (with/without alcohol or cannabis) had a non-synergistic effect on nine disease categories in AN patients, eight in BN patients and seven in USED patients.

CONCLUSIONS

The present study documents non-synergistic but not synergistic harmful somatic consequences of SUDs among patients with different EDs, with AN and hard drugs being the most predominant factors. Hence, EDs and SUDs did not interact and result in greater somatic disease risk than that caused by the independent effects. Since EDs and SUDs have independent effects on many somatic diseases, it is important to monitor and treat ED patients for SUD comorbidity to prevent exacerbated physical damage in this vulnerable population.

Effect of material tramadol on some blood components of laboratory rats

The current study deal with the effect of tramadol injections on body weight and some blood components in 40 male laboratory rats, divided into four groups. The first group, G1 represents the control group. The second group G2 and the third group G3 were injected with a concentration of 20 and 40 mg/100 g of body weight, respectively, and the fourth group G4 was injected at a concentration of 80 mg / 100 g of body weight for ten days respectively. The current study results showed a significant decrease in the weights of rats injected with tramadol compared to the control group. Also, there was a significant decrease in the numbers of RBC, PLT, MID#, and GRAN#, respectively. The concentrations of each of the following constants: HGB, HCT, MCV, MCH, and MCHC showed a significant decrease in their values; except for MCV, the decrease was not significant, and the results of this study also recorded a significant increase in the white blood cells count as well as the number of lymphocytes, and there was an increase in both RDW-CV & RDW-SD. Keywords. Body weight, tramadol, RBC, WBC, PLT.

Predictors of poor bowel preparations and colonoscopy cancellations in inpatient colonoscopies, a single center retrospective study

BACKGROUND

An adequate bowel preparation prior to colonoscopy is a major quality-limiting factor that determines both the diagnostic and therapeutic yield of a colonoscopy. Colonoscopy is considered the gold standard for colon cancer screening and it is the primary approach to the workup of hematochezia, diarrhea and iron deficiency anemia (IDA). Several modifiable factors of bowel prep adequacy have been identified, that account for around 25% of inadequate bowel preparations in outpatient colonoscopies. However, the literature is sparse when examining the factors associated with inadequate preparations and procedure cancellations in an inpatient hospital setting. We aim to identify factors that affect bowel preparation adequacy and procedure cancellations among diagnostic colonoscopies performed during hospitalization.

METHODS

We retrospectively reviewed the electronic medical records of 1,500 consecutive patients who had a diagnostic colonoscopy as an inpatient at a tertiary level hospital over a 2-year period. All patients were administered a clear liquid diet the day prior to the colonoscopy. Patients were then instructed to drink 4 L of polyethylene glycol (PEG, Golytely) between 5 am to 9 am on the day of the procedure. The clinical course of each case was followed to identify quality of preparations, cancelled procedures and the reasons for cancellations. We applied univariate and multivariate logistic regression analysis to identify variables to predict cancellation and poor preparation.

RESULTS

A total of 1,029 patients were included in the study. 194 (18.8%) patients had colonoscopy cancellations and 268 (26.0%) had poor bowel preparations. Multivariate analysis revealed these factors to be associated with colonoscopy cancellations: education at the graduate school level [odds ratio (OR) =1.93, P=0.04], Hispanic ethnicity (OR =0.47, P<0.01), hemoglobin level <10 g/dL (OR =1.41, P=0.05) and if the colonoscopy was done for other indications (OR =0.53, P=0.04). Factors associated with poor bowel preparation on multivariate analysis, were dementia (OR =2.44, P=0.02), gastroparesis (OR =3.97, P=0.01) and inpatient opioids use (OR =1.69, P=0.04).

CONCLUSIONS

The rate of colonoscopy cancellations and poor bowel preparations in inpatient colonoscopies were high, and we were able to identify predictors of inadequate colon preparation and procedure cancellations. Exploring more individualized colon preparation regimens based on personal risk factors could reduce the number of inadequate and cancelled colonoscopies in an inpatient setting.

Postoperative bowel complications after non-shunt-related neurosurgical procedures: case series and review of the literature

Postoperative bowel complications after non-shunt-related neurosurgical procedures are relatively rare. In an effort to identify the primary risk factors, we evaluated postoperative bowel complications in cranial, endovascular, and spinal procedures in neurosurgery patients using our own institutional case series along with a literature review.We identified severe postoperative bowel complications that occurred at our institution after non-shunt-related neurosurgical procedures between July 2016 and December 2018. We also completed a systematic review of PubMed/MEDLINE using search terms related to bowel complications.At our institution, 7 patients (average age 49.7 ± 9.5 years, range 34-60; no apparent sex predilection) had severe postoperative bowel complications after undergoing a total of 10 neurosurgical procedures. Diagnosis was on average 1 week postoperatively (range 5-13 days), and the time between radiographic/clinical diagnosis and either surgery or death was 1.3 ± 1.4 days (range 0-4 days). Bowel perforation occurred in 4 patients. Five of the patients died, 3 as a direct result of the bowel complication. In the literature review, we identified 6487 spine and 66 cranial and/or endovascular bowel complications after neurosurgical procedures.Our case series and literature review demonstrate that severe postoperative bowel complications after non-shunt-related neurosurgical procedures, while rare, carry significant morbidity/mortality despite prompt and aggressive management. These can also happen without direct injury to bowel tissue, instead occurring as sequelae of inflammatory processes, as well as from delayed mobility, extended use of opiate narcotics, and lack of standardized protocols to ensure early bowel movements that likely stems from unfamiliarity with this potentially devastating complication.

Opioid-Sparing Multimodal Analgesia Protocol for Lumpectomy Patients Results in Superior Postoperative Pain Control

Background

We sought to determine if lumpectomy patients who received perioperative opioid-sparing multimodal analgesia reported less pain when compared with those who received traditional opioid-based care.

Study Design

A prospective cohort of patients undergoing lumpectomy who received an opioid-sparing multimodal analgesia protocol [no opioids group (NOP)] was compared with a large cohort of patients who received traditional care [opioids group (OG)]. In-hospital and discharge opioids were compared using oral morphine equivalents (OMEs). Postoperative day one and week one pain scores were compared using the Kruskal–Wallis test.

Results

Overall, 1153 patients underwent lumpectomy: 634 patients received the protocol (NOP), and 519 patients did not (OG). Median pain scores were significantly lower in the NOP cohort when compared with the OG cohort the day after surgery (2 vs. 0, p < 0.001) and the week after surgery (1 vs. 0, p < 0.001). NOP patients were significantly less likely to report severe pain (7–10 on a 10-point scale) the day after surgery compared with OG patients (15.7% vs. 6.9%, p = 0.004). Patients in the NOP cohort were discharged with a median of zero OMEs (range 0–150), while patients in the OG were discharged with a median of 90 OMEs (range 0–360; p < 0.001).

Conclusion

Implementation of an opioid-sparing multimodal analgesia protocol for lumpectomy patients resulted in superior pain control without a routine opioid prescription. Surgeons can improve their own patients’ outcomes while addressing the larger societal issue of the opioid crisis by adopting similar protocols that decrease the quantity of opioids available for diversion.

Opium and risk of gastrointestinal cancer: a case-control study

Background/aim

Gastrointestinal (GI) cancers are among the most common cancers in the world. Many risk factors may increase the chance of developing GI cancers. In recent years, a number of epidemiological studies have reported evidence of carcinogenic effects of opium in humans. This study aimed to investigate the relationship between opium use and GI cancer.

Materials and methods

This case-control study was performed on 95 patients with GI cancer and 190 healthy individuals (matched for age, sex, place of residence, and smoking) in Rafsanjan, Iran, in 2018. Diet information, as well as history of smoking, the use of hookah, opium, and its derivatives was collected using a checklist in interview sessions. Conditional logistic regression was performed to investigate the proposed relationship and to estimate odds ratios (OR).

Results

After adjusting the confounding variables, the use of opium was significantly associated with an increased risk of GI cancer development (OR = 5.95, 95% CI: 2.4–14.9). Also, a dose-response association was found between the cumulative use of opium and the risk of GI cancers. Consumption of fruit and vegetables reduced the risk of developing GI cancers in opium users (OR = 4.9 and 4.7, respectively).

Conclusion

Opium, in the form used among drug users in this area, can lead to an increased risk of GI cancers. Fruit and vegetables have a protective and modifying effect on the risk of GI cancer development caused by opium consumption.

Depletion of the Microbiome Alters the Recruitment of Neuronal Ensembles of Oxycodone Intoxication and Withdrawal

Substance use disorders have a complex etiology. Genetics, the environment, and behavior all play a role in the initiation, escalation, and relapse of drug use. Recently, opioid use disorder has become a national health crisis. One aspect of opioid addiction that has yet to be fully examined is the effects of alterations of the microbiome and gut-brain axis signaling on central nervous system activity during opioid intoxication and withdrawal. The effect of microbiome depletion on the activation of neuronal ensembles was measured by detecting Fos-positive (Fos+) neuron activation during intoxication and withdrawal using a rat model of oxycodone dependence. Daily oxycodone administration (2 mg/kg) increased pain thresholds and increased Fos+ neurons in the basolateral amygdala (BLA) during intoxication, with a decrease in pain thresholds and increase in Fos+ neurons in the periaqueductal gray (PAG), central nucleus of the amygdala (CeA), locus coeruleus (LC), paraventricular nucleus of the thalamus (PVT), agranular insular cortex (AI), bed nucleus of the stria terminalis (BNST), and lateral habenula medial parvocellular region during withdrawal. Microbiome depletion produced widespread but region- and state-specific changes in neuronal ensemble activation. Oxycodone intoxication and withdrawal also increased functional connectivity among brain regions. Microbiome depletion resulted in a decorrelation of this functional network. These data indicate that microbiome depletion by antibiotics produces widespread changes in the recruitment of neuronal ensembles that are activated by oxycodone intoxication and withdrawal, suggesting that the gut microbiome may play a role in opioid use and dependence. Future studies are needed to better understand the molecular, neurobiological, and behavioral effects of microbiome depletion on addiction-like behaviors.

Opioid-Induced Constipation in Oncological Patients: New Strategies of Management

OPINION STATEMENT

Cancer-associated pain has traditionally been treated with opioid analgesics, often in escalating doses. Opioid-induced constipation (OIC) is a common problem associated with chronic use of opioid analgesics. Typical treatment strategies to alleviate constipation are based on dietary changes, exercise, and laxatives. However, laxatives have a nonspecific action and do not target underlying mechanisms of OIC. This article will review prevalent, clinical presentation and recommendations for the treatment of OIC. An independent literature search was carried out by the authors. We reviewed the literature for randomized controlled trials that studied the efficacy of laxatives, naloxone, and naloxegol in treating OIC. Newer strategies addressing the causal pathophysiology of OIC are needed for a more effective assessment and management of OIC. Finally, traditional recommended therapies are appraised and compared with the latest pharmacological developments. Future research should address whether naloxegol is more efficacious by its comparison directly with first-line treatments, including laxatives.

The Association Between Opioid Use and Outcomes in Infants Undergoing Pyloromyotomy

PURPOSE

The purpose of this study was to describe the frequency and variation of opioid use across hospitals in infants undergoing pyloromyotomy and to determine the impact of opioid use on postoperative outcomes.

METHODS

A retrospective cohort study (2005-2015) was conducted by using the Pediatric Health Information System (PHIS) database, including infants (aged <6 months) with pyloric stenosis who underwent pyloromyotomy. Infants with significant comorbidities were excluded. Opioid use was classified as a patient receiving at least 1 opioid medication during his or her hospital stay and categorized as preoperative, day of surgery, or postoperative (≥1 day after surgery). Outcomes included prolonged hospital length of stay (LOS; ≥3 days) and readmission within 30 days.

FINDINGS

Overall, 25,724 infants who underwent pyloromyotomy were analyzed. Opioids were administered to 6865 (26.7%) infants, with 1385 (5.4%) receiving opioids postoperatively. In 2015, there was significant variation in frequency of opioid use by hospital, with 0%-81% of infants within an individual hospital receiving opioids (P < 0.001). Infants only receiving opioids on the day of surgery exhibited decreased odds of prolonged hospital LOS (odds ratio [OR], 0.85; 95% CI, 0.78-0.92). Infants who received an opioid on both the day of surgery and postoperatively exhibited increased odds of a prolonged hospital LOS (OR, 1.71; 95% CI, 1.33-2.20). Thirty-day readmission was not associated with opioid use (OR, 1.03; 95% CI, 0.93-1.14).

IMPLICATIONS

There is national variability in opioid use for infants undergoing pyloromyotomy, and postoperative opioid use is associated with prolonged hospital stay. Nonopioid analgesic protocols may warrant future investigation.

Tapentadol Prolonged Release: A Review in Pain Management

Tapentadol prolonged release (tapentadol PR) [Palexia® SR in EU] is a long-acting tablet formulation of the strong central analgesic tapentadol, which acts as both a μ-opioid receptor (MOR) agonist and a noradrenaline reuptake inhibitor. Tapentadol PR is approved for chronic pain in various countries, with its EU indication (severe chronic pain manageable only with opioid analgesics) being the focus here. Well-designed trials and clinical practice data support tapentadol PR use in this setting. Short term, tapentadol PR was an effective and generally well tolerated analgesic for moderate to severe pain of varying aetiologies, including neuropathic pain. It provided analgesia at least as good as that of conventional strong opioids and appeared more favourable in terms of gastrointestinal tolerability, likely due to less potent MOR binding. Severe back pain with a neuropathic component responded well to moderate-dose tapentadol PR in some patients, while for others, an increase to the maximum recommended tapentadol PR dosage provided analgesia at least as good as that of moderate-dose tapentadol PR plus pregabalin and appeared to have some CNS tolerability benefits. Data also support the use of tapentadol PR in opioid rotation, including when conventional opioids are intolerable. Longer-term data in musculoskeletal pain conditions indicate continued benefit over up to 2 years' treatment with tapentadol PR with no evidence of tolerance. Thus, tapentadol PR is a useful option for the management of severe chronic pain.

Prevalence of Chronic Constipation and Its Associated Factors in Pars Cohort Study: A Study of 9000 Adults in Southern Iran

BACKGROUND

Chronic constipation is one of the most common gastrointestinal disorders. It has negative effects on the patients’ quality of life, and their productivity, and results in a high economic burden on the healthcare services. The aim of the present study was to estimate the prevalence of chronic constipation and its associated factors in pars cohort study (PCS).

METHODS

A cross-sectional study was conducted on the baseline data of the PCS. Data gathering was done by structured questionnaire and physical examination. A total of 9264 subjects aged between 40 and 75 years were enrolled in the PCS. Diagnosis of chronic constipation was done using Rome IV criteria. Multivariable binary logistic regression was applied for data analysis.

RESULTS

A total of 752 (8.1%) participants were diagnosed as having chronic constipation (9.3% of female and 6.7% of male participants). Older age (OR: 1.55, 95% CI: 1.31-1.83), physical activity (OR: 0.56, 95% CI: 0.46-0.68), opium consumption (OR: 2.06, 95% CI: 1.63-2.60) , anxiety (OR: 1.38, 95% CI: 1.15-1.65), depression (OR: 1.22, 95% CI: 1.01-1.48), back pain or arthralgia (OR: 1.38, 95% CI: 1.14-1.67), insomnia (OR: 1.62, 95% CI: 1.36-1.93) and gastroesophageal reflux disease (OR: 1.51, 95% CI: 1.28-1.78) were associated with the prevalence of constipation in the multivariable analysis.

CONCLUSION

Chronic constipation was a common problem in the PCS population. Decreasing modifiable risk factors associated with constipation such as opium consumption and physical inactivity can reduce its prevalence and decrease burden of the disease.

Opioid misuse in gastroenterology and non-opioid management of abdominal pain

Opioids were one of the earliest classes of medications used for pain across a variety of conditions, but morbidity and mortality have been increasingly associated with their chronic use. Despite these negative consequences, chronic opioid use is increasing worldwide, with the USA and Canada having the highest rates. Chronic opioid use for noncancer pain can have particularly negative effects in the gastrointestinal and central nervous systems, including opioid-induced constipation, narcotic bowel syndrome, worsening psychopathology and addiction. This Review summarizes the evidence of opioid misuse in gastroenterology, including the lack of evidence of a benefit from these drugs, as well as the risk of harm and negative consequences of opioid use relative to the brain-gut axis. Guidelines for opioid management and alternative pharmacological and nonpharmacological strategies for pain management in patients with gastrointestinal disorders are also discussed. As chronic pain is complex and involves emotional and social factors, a multimodal approach targeting both pain intensity and quality of life is best.

Pharmacokinetics and Adverse Effects of 3 Sustained-release Buprenorphine Dosages in Healthy Guinea Pigs (Cavia porcellus)

In guinea pigs, studies addressing the efficacy, safety, and pharmacokinetic profiles of different sustained-release buprenorphine (SRB) formulations are still in their infancy. Here we assessed the pharmacokinetic profiles of 3 SRB dosages (SR-LAB, ZooPharm; SRBLow, 0.15 mg/kg; SRBMedium, 0.3 mg/kg; and SRBHigh, 0.6 mg/kg) for 72 h after a single subcutaneous administration to 8 (4 male and 4 female) healthy guinea pigs. Body weight, fecal output, and cortisol levels were also monitored and the results compared with those of the sham group. Within the first h after administration, the maximal plasma concentration (Cmax) of the drug was 64.3 ± 9.2 ng/mL (males) and 71.3 ± 3.7 ng/mL (females) in the SRBHigh group; 11.5 ± 3.2 ng/mL (males) and 6.9 ± 0.9 ng/mL (females) in the SRBMedium group; and 2.3 ± 0.8 ng/mL (males) and 2.0 ± 0.5 ng/mL (females) in the SRBLow group. After 72 h, therapeutic levels of the drug (>1 ng/mL) were observed only in guinea pigs treated with SRBHigh (both sexes) and males treated with SRBMediu cm. Fecal output (quantity and distribution) and body weight were significantly lower in the SRB groups as compared with the sham group, and with the SRBHigh group showing larger reductions. Baseline levels of serum cortisol in healthy females (1440 ± 106 ng/mL) were significantly greater than in males (550 ± 66 ng/mL). But, independent of the sex, SRB administration significantly reduced those levels. In conclusion, the data indicate that all 3 SRB dosages can be safely used in guinea pigs. However, therapeutic levels of the drug were observed for at least 48 h only guinea pigs treated with SRBHigh and SRBMedium. Further investigation is needed to determine if these dosages can alleviate pain in guinea pigs.

The Efficacy and Safety of Transcutaneous Acupoint Interferential Current Stimulation for Cancer Pain Patients With Opioid-Induced Constipation: A Prospective Randomized Controlled Study

Introduction. Opioid-induced constipation (OIC) is a principal complication secondary to analgesic therapy for cancer pain patients who suffer moderate to severe pain. In this study, we observe the efficacy and safety of transcutaneous acupoint interferential current (IFC) stimulation in those patients with OIC. Methods. A total of 198 patients were randomly allocated to the IFC group and control group in a 1:1 ratio. Finally, 98 patients in the IFC group received 14 sessions administered over 2 weeks, whereas 100 patients in the control group took lactulose orally during the same period. Observation items were documented at management stage and at follow-up stage according to Cleveland Constipation Scales (CCS), pain Numeric Rating Scales (NRS) and Patient Assessment of Constipation Quality of Life (PAC-QoL). Results. The total curative effects of the IFC group and the control group were indistinguishable (76.5% vs 70.0%, P = .299). Regarding CCS and PAC-QoL scores, no significant difference was observed between the 2 groups during the management time and at the follow-up stage of week 3 (P > .05, respectively), but groups were distinguished at the follow-up stage of week 4 (P < .001 and P = .031, respectively). The pain NRS decreased significantly at management stage week 2 and follow-up stage week 3 and week 4 (P = .013, P = .041, P = .011, respectively). Conclusions. Transcutaneous acupoint IFC therapy over acupoints of Tianshu (ST25) and Zhongwan (RN12) may improve constipation and quality of life in cancer patients receiving opiates; further studies are worthwhile.

Cost-effectiveness analysis of oxycodone with naloxone versus oxycodone alone for the management of moderate-to-severe pain in patients with opioid-induced constipation in Canada

BACKGROUND

Approximately 20-30% of Canadians suffer from chronic pain. Guidelines for the management of chronic pain support the use of controlled-release (CR) opioids to treat chronic pain. Although effective in managing chronic pain, oxycodone is associated with high rates of opioid-induced constipation (OIC). The cost-effectiveness of a combination of oxycodone for the management of pain and naloxone for the relief of OIC has not previously been evaluated for Canada.

METHODS

A decision analytic model was developed to estimate the cost-utility of combination oxycodone/naloxone compared to oxycodone alone in four populations. Drug costs for managing pain and healthcare costs related to managing OIC were included in the analysis and the primary measure of effectiveness was quality adjusted life years (QALYs) derived from OIC rates observed in clinical trials. The analysis was conducted from a healthcare system perspective, used a 1-year time horizon, and results were expressed in 2015 Canadian dollars.

RESULTS

In all four patient populations, there was a trade-off between slightly higher total expected costs for Targin treated patients compared to oxycodone treated patients, but also improved clinical benefits in terms of reduced OIC, which resulted in higher QALYs for patients. Although analgesic costs were found to be slightly higher for Targin treated patients, Targin also resulted in cost offsets to the healthcare system in terms of less rescue laxative drug use and other resources required for the management of OIC. The resulting 1-year cost-utility of Targin compared to oxycodone ranged from $2178-$7732 per QALY gained in the base case analysis, and it was found that these cost-utility results remained robust and at low values throughout a series of one-way deterministic analyses of uncertainty.

CONCLUSION

The clinical effectiveness of oxycodone/naloxone in managing pain and OIC compared to CR oxycodone alone resulted in low cost-utility estimates.

Development of opioid-induced constipation: post hoc analysis of data from a 12-week prospective, open-label, blinded-endpoint streamlined study in low-back pain patients treated with prolonged-release WHO step III opioids

BACKGROUND

Opioid-induced constipation is the most prevalent patient complaint associated with longer-term opioid use and interferes with analgesic efficacy, functionality, quality of life, and patient compliance.

OBJECTIVES

We aimed to compare the effects of prolonged-release (PR) oxycodone plus PR naloxone (OXN) vs PR oxycodone (OXY) vs PR morphine (MOR) on bowel function under real-life conditions in chronic low-back pain patients refractory to World Health Organization (WHO) step I and/or II analgesics.

RESEARCH DESIGN AND METHODS

This was a post hoc analysis of the complete data set from a prospective, randomized, open-label, blinded endpoint (PROBE) streamlined study (German pain study registry: 2012-0012-05; European Union Drug Regulating Authorities Clinical Trials [EudraCT]: 2012-001317-16), carried out in 88 centers in Germany, where a total of 901 patients requiring WHO step III opioids to treat low-back pain were enrolled and prospectively observed for 3 months. Opioid allocation was based on either optional randomization (n=453) or physician decision (n=448). In both groups, treatment doses could be adjusted as per the German prescribing information, and physicians were free to address all side effects and tolerability issues as usual. The primary endpoint was the proportion of patients maintaining normal bowel function throughout the complete treatment period, assessed with the Bowel Function Index (BFI). Secondary analyses addressed absolute and relative BFI changes, complete spontaneous bowel movements, use of laxatives, treatment emergent adverse events, analgesic effects, and differences between randomized vs nonrandomized patient groups.

RESULTS

BFI changed significantly with all three WHO step III treatments, however significantly less with OXN vs OXY and MOR despite a significantly higher use of laxatives with the latter ones (P<0.001). The percentage of patients who maintained normal BFI scores despite opioid treatment was 54.5% (164/301) with OXN and was significantly superior to those seen with OXY (32.8% [98/300]) (odds ratio [OR]: 2.47, 95% confidence interval [CI]: 1.77-3.44; P<0.001) or MOR (29.7% [89/300]) (OR: 2.84, 95% CI: 2.03-3.97; P<0.001). Absolute BFI changes of ≥12mm 100 mm horizontal visual analog scale (VAS100) vs. baseline were seen for OXN in 41.4%, for OXY in 68.7%, and for MOR in 72.3%. Complete spontaneous bowel movements decreased at least by one per week in 10.3% with OXN vs 42.3% for OXY (OR: 6.39, 95% CI 4.13-9.89; P<0.001) and 42.0% for MOR (OR: 6.31, 95% CI: 4.08-9.76; P<0.001). Overall, 359 treatment emergent adverse events (78 [OXN], 134 [OXY], and 147 [MOR]) in 204 patients (41 [OXN], 80 [OXY], and 83 [MOR]) occurred, most affecting the gastrointestinal (49.3%) and the nervous system (39.3%). Treatment contrasts between randomized vs nonrandomized patients were insignificant.

CONCLUSION

In this post hoc analysis of data from a real-life 12-week study, OXN treatment was associated with a significantly lower risk of opioid-induced constipation, superior tolerability, and significantly better analgesic efficacy compared with OXY and MOR.

Zinc involvement in opioid addiction and analgesia--should zinc supplementation be recommended for opioid-treated persons?

INTRODUCTION

Zinc chelators were shown to facilitate some opioid-withdrawal signs in animals. Zinc deficiency, which affects more than 15% the world's population, is also common among opioid consumers and opioid-treated animals exhibit misbalances of zinc distribution.

AIM

The present study focuses on how zinc ions interfere with opioid dependence/addiction and analgesia, trying to preliminary discuss if zinc supplementation in opioid-users should be recommended in order to reduce the risk of addiction.

METHODS

All relevant literature was searched up to April 2015. The search was performed using the term "zinc" plus combinations of following terms: "opioid receptors", "opioid" or representatives of this class, "addiction", "dependence", "analgesia", and "pain". Human, animal, in vitro studies and reviews were including.

RESULTS

Both human and animal studies revealed decreased serum zinc under opioid-administration conditions, attributed mainly to increased urinary elimination (humans) or redistribution (animals). Moreover, animal studies revealed decreased brain zinc levels in morphine-treated animals, with increased zinc hepatic levels, but also an enhancement of endogenous opioid system activity and a possible reduction of morphine withdrawal by zinc. In vitro studies revealed reduction of opioid ligands binding to receptors by zinc. However, the very few in vivo animal studies on opioid analgesia revealed controversial results, as zinc demonstrated clear analgesic effect, but zinc associated to opioids doesn't result in a potentiation of the analgesic effect.

CONCLUSION

Zinc dietary supplementation in patients treated with opioids for cancer-related chronic pain should be considered, due to the high incidence of zinc deficiency, also well-documented in opioid consumers. The low toxicity of orally-administered zinc also pleads for this idea. The main contra-argument to zinc administration in opioid-treated persons is related to the way zinc influences opioid-induced analgesia.

Emerging therapies for patients with symptoms of opioid-induced bowel dysfunction

Opioid-induced bowel dysfunction (OIBD) comprises gastrointestinal (GI) symptoms, including dry mouth, nausea, vomiting, gastric stasis, bloating, abdominal pain, and opioid-induced constipation, which significantly impair patients’ quality of life and may lead to undertreatment of pain. Traditional laxatives are often prescribed for OIBD symptoms, although they display limited efficacy and exert adverse effects. Other strategies include prokinetics and change of opioids or their administration route. However, these approaches do not address underlying causes of OIBD associated with opioid effects on mostly peripheral opioid receptors located in the GI tract. Targeted management of OIBD comprises purely peripherally acting opioid receptor antagonists and a combination of opioid receptor agonist and antagonist. Methylnaltrexone induces laxation in 50%–60% of patients with advanced diseases and OIBD who do not respond to traditional oral laxatives without inducing opioid withdrawal symptoms with similar response (45%–50%) after an oral administration of naloxegol. A combination of prolonged-release oxycodone with prolonged-release naloxone (OXN) in one tablet (a ratio of 2:1) provides analgesia with limited negative effect on the bowel function, as oxycodone displays high oral bioavailability and naloxone demonstrates local antagonist effect on opioid receptors in the GI tract and is totally inactivated in the liver. OXN in daily doses of up to 80 mg/40 mg provides equally effective analgesia with improved bowel function compared to oxycodone administered alone in patients with chronic non-malignant and cancer-related pain. OIBD is a common complication of long-term opioid therapy and may lead to quality of life deterioration and undertreatment of pain. Thus, a complex assessment and management that addresses underlying causes and patomechanisms of OIBD is recommended. Newer strategies comprise methylnaltrexone or OXN administration in the management of OIBD, and OXN may be also considered as a preventive measure of OIBD development in patients who require opioid administration.

Prevalence of narcotic bowel syndrome in opioid abusers in iran

BACKGROUND In spite of the increasing trend in opioid abusers worldwide, the prevalence of narcotic bowel syndrome (NBS) is undetermined. We aimed to estimate the prevalence of NBS and other opioid bowel dysfunction (OBD) in opioid abusers in Kerman, southeast Iran. According to the best of our knowledge, this is the first study to assess the prevalence of NBS in opioid abusers. METHODS By referring to addiction treatment centers in Kerman city and in a cross-sectional study, 577 subjects with opium or opioid subtracts abuse were included in our study. A validated questionnaire was used for OBD assessment and diagnosis of NBS was made according to both the presence of chronic abdominal pain despite increasing the opioid dose and ruling out other causes of abdominal pain. SPSS software version 16 was used for data analysis. p value<0.05 was considered as statistically significant. RESULTS Constipation, regurgitation, and heartburn were the most gastrointestinal complaints that were found in 132(22.9%), 123(21.3%) and 91(15.8%) subjects, respectively. Only 16(2.8%) participants fulfilled all the NBS criteria. Simultaneous use of non-narcotic sedative drugs increased the risk of NBS significantly (the odds ratio 3:1 and p=0.049). CONCLUSION NBS is not rare among opioid abusers and should be considered as a cause of chronic abdominal pain in this group.

Oxycodone/Naloxone: role in chronic pain management, opioid-induced constipation, and abuse deterrence

The use of opioids in the treatment of chronic pain is widespread; the prevalence of specific opioids varies from country to country and depends on product availability, national formulary systems, and provider preferences. Patients often receive opioids for legitimate treatment of pain conditions, but on the opposite side of the spectrum, nonmedical use of opioids is a significant public health concern. Opioids are associated with several side effects, and constipation is the most commonly reported and persistent symptom. Unlike some adverse effects associated with opioid use, tolerance does not develop to constipation. Opioid-induced constipation (OIC) is the most prevalent patient complaint associated with opioid use and has been associated with declines in various quality of life measures. OIC can be extremely difficult for patients to tolerate and may prompt patients to decrease or discontinue opioid treatment. Current management strategies for OIC are often insufficient. A prolonged-release formulation of oxycodone/naloxone (OXN) has been investigated for the treatment of nonmalignant and cancer pain and mitigation of OIC, and evidence is largely favorable. Studies have demonstrated the capability of OXN to alleviate OIC while maintaining pain control comparable to oxycodone-only regimens. There is insufficient evidence for OXN efficacy for patients with mild OIC or patients maintained on high doses of opioids, and use in these populations is controversial. The reduction of costs associated with OIC may provide overall cost effectiveness with OXN. Additionally, the presence of naloxone may deter abuse/misuse by those seeking to misuse the formulation by modes of administration other than oral ingestion. Most studies to date have occurred in European countries, and phase 3 trials continue in the United States. This review will include current therapeutic options for pain and constipation, unique characteristics of OXN, evidence related to use of OXN and its place in therapy, discussion of opioid abuse/misuse, and various abuse-deterrent mechanisms, and areas of continuing research.

A review of the clinical manifestations, pathophysiology and management of opioid bowel dysfunction and narcotic bowel syndrome

Opioids are widely used for the treatment of malignant and non-malignant pains. These medications are accompanied by adverse effects, in particular gastrointestinal symptoms known as opioid bowel dysfunction (OBD). The most common symptom of OBD is refractory constipation that is usually stable regardless of the use of laxatives. Narcotic bowel syndrome (NBS) is a subset of OBD described as ambiguous chronic pain aggravated by continual or increased opioid use for pain relief. Pathophysiology of these disorders are not definitely disentangled. Some challenging hypothesis have been posed leading to specific management in order to mitigate the adverse effects. This article is a review of the literature on the prevalence, pathophysiology and management of OBD and NBS.

The place of oxycodone/naloxone in chronic pain management

Opioid analgesics are usually effective in the management of severe chronic pain. However, symptoms of opioid-induced bowel dysfunction (OIBD) are common during opioid therapy. Opioid-induced bowel dysfunction is often unsuccessfully managed due to limited effectiveness and numerous adverse effects of traditional laxatives. Newer treatment possibilities directed at the pathomechanism of OIBD comprise combined prolonged-release oxycodone with prolonged-release naloxone (oxycodone/naloxone) tablets. Oxycodone/naloxone provides effective analgesia with limited impact on bowel function as oxycodone displays high oral bioavailability and naloxone act as local antagonist on opioid receptors in the gastrointestinal tract due to nearly complete inactivation in the liver. Oxycodone/naloxone is administered to opioid-naive patients with severe pain and those unsuccessfully treated with weak opioids. Oxycodone/naloxone may be also administered to patients treated with strong opioids who experience intense symptoms of OIBD. Studies conducted to date indicate that oxycodone/naloxone is an important drug in chronic pain management, prevention and treatment of OIBD.