Efficacy of Naldemedine on Intestinal Hypomotility and Adhesions in Rodent Models of Postoperative Ileus

Postoperative ileus (POI) often decreases patients' QOL because of prolonged hospitalization and readmission. Alvimopan, a peripheral μ-opioid receptor antagonist, is currently the only therapeutic drug for POI. The aim of this study was to examine the efficacy of naldemedine (a peripheral μ-opioid receptor antagonist with a non-competitive pharmacological profile different from that of alvimopan) on postoperative intestinal hypomotility and adhesion in rodent models, and compare it with the effects of alvimopan. Oral administration of naldemedine (0.3 mg/kg) and alvimopan (3 mg/kg) significantly inhibited the decrease in intestinal motility induced by mechanical irritation in mice (p < 0.01, for both). Naldemedine (1 mg/kg) significantly shortened the adhesion length in chemical-induced postoperative adhesion model rats (p < 0.05). Alvimopan (3 mg/kg) also significantly reduced the adhesion ratio (p < 0.01). These findings suggest that naldemedine is effective for postoperative intestinal hypomotility and adhesions in rodents (i.e., as for alvimopan). Thus, naldemedine may be a useful option for the treatment of POI.

The effect of simethicone on postoperative ileus in patients undergoing colorectal surgery (SPOT), a randomized controlled trial

BACKGROUND

Postoperative ileus is a poorly understood multifactorial outcome following colorectal surgery that presents significant clinical challenges and contributes to increased morbidity, length of stay, and healthcare cost. To date, there are few pharmacological interventions that shorten the duration of postoperative ileus.

OBJECTIVE

This study is the first to evaluate the efficacy of simethicone in treating postoperative ileus symptoms in patients undergoing colorectal surgery.

DESIGN

A multicenter, double-blinded, placebo controlled randomized controlled trial.

SETTINGS

This trial was conducted at two academic tertiary care centres in Ontario, Canada.

PARTICIPANTS

118 patients undergoing colorectal surgery.

INTERVENTIONS

Patients were randomized to receive either a five-day course of oral simethicone (n = 58) or a placebo (n = 60).

MAIN OUTCOME MEASURES

The primary outcome was time to first passage of flatus. Secondary outcomes included time to first bowel movement, postoperative length of stay, and postoperative pain. Statistical analyses were performed on an intention-to-treat basis. Statistical significance set at p = 0.05.

RESULTS

The median time to first passage of flatus in simethicone arm was 25.2 h and 26.7 h in controls (P = 0.98). There were no significant differences in the median time to first bowel movement (simethicone = 41.1 h vs. control = 42.9 h, P = 0.91) or median length of hospital stay (simethicone = 4.5 days vs. control = 4.0 days, P = 0.63).

CONCLUSIONS

This study failed to show a difference in return of gastrointestinal motility in patients receiving simethicone following colorectal surgery. Postoperative ileus remains a significant clinical and economic burden to the healthcare system and further research is needed to identify a reliable and effective method of treatment.

Cardiovascular Safety of the Selective μ-Opioid Receptor Antagonist Naloxegol: A Novel Therapy for Opioid-Induced Constipation

Background:

Naloxegol is a novel selective, peripherally acting μ-opioid receptor antagonist for treating opioid-induced constipation (OIC) in patients with chronic pain syndromes. We analyzed the cardiovascular (CV) safety of naloxegol based on data from its development program prior to approval by the US Food and Drug Administration in 2015.

Methods:

Comprehensive CV safety analyses were performed in 4 clinical studies of naloxegol (12.5 and/or 25 mg) in patients with noncancer pain and OIC: two 12-week, double-blind, randomized studies; a 12-week, double-blind, extension study; and a 52-week, randomized, open-label study versus usual care. Evaluations of baseline CV risk were obtained from medical histories and clinical findings at the time of study initiation.

Results:

Across the 4 studies (N = 2135), 68% of patients had ≥1 CV risk factor and 41% had a history of CV disease, diabetes, or ≥2 other CV risk factors. There were no increases in blood pressure, heart rate, or the rate-pressure product with naloxegol versus placebo. The rates of major adverse cardiovascular events (MACE) per 100 patient-years of exposure were 1.13 (95% confidence interval [CI], 0.31-2.89) for placebo/usual care and 0.75 (95% CI, 0.24-1.75) for naloxegol. The relative risk of MACE for all doses of naloxegol versus placebo was 0.67 (95% CI, 0.14-3.36).

Conclusion:

These data demonstrate that naloxegol has a CV safety profile comparable to placebo/usual care in patients with OIC. Although the observed number of events was low, the data show no CV signal in patients with OIC treated with naloxegol.

Prospective study comparing laparoscopic and open radical cystectomy: Surgical and oncological results

INTRODUCTION

Laparoscopic radical cystectomy with lymphadenectomy and urinary diversion is an increasingly widespread operation. Studies are needed to support the oncological effectiveness and safety of this minimally invasive approach.

PATIENTS AND METHODS

A nonrandomised, comparative prospective study between open radical cystectomy (ORC) and laparoscopic radical cystectomy (LRC) was conducted in a university hospital. The main objective was to compare cancer-specific survival. The secondary objective was to compare the surgical results and complications according to the Clavien-Dindo scale.

RESULTS

We treated 156 patients with high-grade invasive bladder cancer with either ORC (n=70) or LRC (n=86). The mean follow-up was 33.5±23.8 (range 12-96) months. The mean age was 66.9+9.4 years, and the male to female ratio was 19:1. Both groups were equivalent in age, stage, positive lymph nodes, in situ carcinoma, preoperative obstructive uropathy, adjuvant chemotherapy and type of urinary diversion. There were no differences between the groups in terms of cancer-specific survival (log-rank; P=.71). The histopathology stage was the only independent variable that predicted the prognosis. The hospital stay (P=.01) and operative transfusion rates (P=.002) were less for LRC. The duration of the surgery was greater for LRC (P<.001). There were no differences in the total complications rate (p=.62) or major complications (P=.69). The risk of evisceration (P=.02), surgical wound infection (P=.005) and pneumonia (P=.017) was greater for ORC. The risk of rectal lesion (P=.017) and urethrorectal fistulae (P=.065) was greater for LRC.

CONCLUSION

LRC is an equivalent treatment to ORC in terms of oncological efficacy and is advantageous in terms of transfusion rates and hospital stays but not in terms of operating room time and overall safety. Studies are needed to better define the specific safety profile for each approach.

Enhanced recovery after surgery: Pain management

Effective pain management is fundamental to enhanced recovery after surgery. Selection of strategies should be tailored to patient and operation. As well as improving the quality of recovery, effective analgesia reduces the host stress response, facilitates mobilization and allows resumption of oral intake. Multi-modal regimens combining paracetamol, non-steroidal anti-inflammatory agents where indicated, a potent opioid and a local anaesthetic technique achieve effective analgesia while limiting the dose and thereby side effects of any one agent.

Opioid-induced constipation

Opioid-induced constipation (OIC) is a very troublesome, difficult to manage and a nearly universal complication of chronic opioid use to control pain associated with advanced illness. Some studies have reported that OIC is so intolerable in some patients that they skip their opioid medications and bear pain instead of OIC. Laxatives have commonly been used as a prophylaxis and treatment of OIC but they are frequently ineffective because the commonly available laxatives do not target the underlying mechanism of OIC, which is the blockade of peripheral mu-receptors. Recently, there have been a number of advances in the treatment of OIC, which any physician involved with opioid-prescribing discipline should be aware of. This review will update the new options and strategies available for treating OIC along with the relevant clinical trials. Finally, this review also provides a recommendation on the preferred way to approach a patient with OIC in the modern era as well as highlight on the importance of doctor-patient communication in this setting.

The Effects of Drinking Coffee While Recovering from Colon and Rectal Resection Surgery

AIM

Resection surgery on the colon and rectum are changing both anatomical and physiological relations within the abdominal cavity. Delayed functions of the gastrointestinal tract, flatulence, failure of peristalsis, prolonged spasms and pain, limited postoperative recovery of these patients increase the overall cost of treatment. Early consumption of coffee instead of tea should lead to faster restoration of normal function of the colon without unwanted negative repercussions.

METHOD

This study is designed as a prospective-retrospective clinical study and was carried out at the Surgery Center Tuzla, during the year 2013/ 2014. Sixty patients were randomized in relation to the type of resection surgery, etiology of disease-malignant benign, and in relation to whether they were coffee users or not. Patients were divided into two groups. The first group of thirty patients was given 100 ml of instant coffee divided into three portions right after removing the nasogastric tube, first postoperative day, while the second group of thirty patients got 100 ml of tea. Monitored parameter was: time of first stool and the second group of monitored parameters was: whether there was returning of nasogastric tube or not, increased use of laxatives, whether there was anastomotic leak, radiologic and clinical dehiscence, audit procedures, or lethal outcomes in the treatment of patients.

RESULTS

A total of 61 patients were randomized into two groups of 30 int he group of tea and coffee 29 in the group, two patients were excluded from the study because they did not consume coffee before surgery. Time of getting stool in the postoperative period after elective resection surgery on the colon and rectum is significantly shorter after drinking coffee for about 15h (p <0.01). Also, the length of hospital stay was significantly shorter after drinking coffee (p <0.01). Time of hospitalization in subjects/respondents coffee consumers on average lasted 8.6 days with consumers of tea for 16 days. The incidence of postoperative complications was significantly lower after consumption of coffee (p <0.05).

CONCLUSION

Postoperative consumption of coffee is a safe and effective way to accelerate the establishment of the bowel function after colorectal resection surgery.

Off-label uses of alvimopan and methylnaltrexone

PURPOSE

Off-label uses of the peripheral μ-opioid receptor antagonists alvimopan and methylnaltrexone are reviewed.

SUMMARY

Alvimopan is approved by the Food and Drug Administration (FDA) for postoperative ileus after surgeries that include partial bowel resection with primary anastomosis, while methylnaltrexone is approved for the treatment of opioid-induced constipation (OIC) in patients with advanced illness who are receiving palliative care. Literature describing the off-label use of alvimopan in the treatment of OIC and of methylnaltrexone in postoperative ileus was reviewed and included retrospective studies and prospective Phase II-IV trials. Randomized controlled trials did not demonstrate consistent benefit of alvimopan in OIC nor of methylnaltrexone in postoperative ileus. A greater proportion of patients receiving alvimopan for OIC experienced severe adverse cardiovascular events, leading to a risk evaluation and mitigation strategy and discontinuation of its study in this condition. Data are limited and unreplicated for the off-label use of alvimopan for postoperative ileus in patients undergoing abdominal hysterectomy. Individual studies suggest benefit with methylnaltrexone for OIC in unlabeled populations, including patients with non-cancer-related pain, opioid dependence, opioid sedation, and opioid use after orthopedic surgery; however, confirmatory evaluations have not been performed.

CONCLUSION

Trials of alvimopan in the FDA-approved use of methylnaltrexone (OIC) indicate potentially serious cardiovascular safety concerns and conflicting findings of efficacy. Similarly, trials of methylnaltrexone in the FDA-approved use of alvimopan (postoperative ileus) consistently showed no benefit. Evaluations of both drugs in their labeled conditions in populations not endorsed in their product labeling have been limited and largely unreplicated.

Impact of postsurgical opioid use and ileus on economic outcomes in gastrointestinal surgeries

OBJECTIVES

To assess the incidence and economic impact of postoperative ileus (POI) following laparotomy (open) and laparoscopic procedures for colectomies and cholecystectomies in patients receiving postoperative pain management with opioids.

METHODS

Using the Premier research database, we retrospectively identified adult inpatients discharged between 2008 and 2010 receiving postsurgical opioids following laparotomy and laparoscopic colectomy and cholecystectomy. POI was identified through ICD-9 diagnosis codes and postsurgical morphine equivalent dose (MED) determined.

RESULTS

A total of 138,068 patients met criteria, and 10.3% had an ileus. Ileus occurred more frequently in colectomy than cholecystectomy and more often when performed by laparotomy. Ileus patients receiving opioids had an increased length of stay (LOS) ranging from 4.8 to 5.7 days, total cost from $9945 to $13,055 and 30 day all-cause readmission rate of 2.3 to 5.3% higher compared to patients without ileus. Patients with ileus received significantly greater MED than those without (median: 285 vs. 95 mg, p < 0.0001) and were twice as likely to have POI. MED above the median in ileus patients was associated with an increase in LOS (3.8 to 7.1 days), total cost ($8458 to $19,562), and readmission in laparoscopic surgeries (4.8 to 5.2%). Readmission rates were similar in ileus patients undergoing open procedures regardless of MED.

CONCLUSIONS

Use of opioids in patients who develop ileus following abdominal surgeries is associated with prolonged hospitalization, greater costs, and increased readmissions. Furthermore, higher doses of opioids are associated with higher incidence of POI. Limitations are related to the retrospective design and the use of administrative data (including reliance on ICD-9 coding). Yet POI may not be coded and therefore underestimated in our study. Assessment of pre-existing disease and preoperative pain management was not assessed. Despite these limitations, strategies to reduce opioid consumption may improve healthcare outcomes and reduce the associated economic impact.

Site and mechanism of morphine tolerance in the gastrointestinal tract

Opioid-induced constipation is a major clinical problem. The effects of morphine, and other narcotics, on the gastrointestinal tract persist over long-term use thus limiting the clinical benefit of these excellent pain relievers. The effects of opioids in the gut, including morphine, are largely mediated by the μ-opioid receptors at the soma and nerve terminals of enteric neurons. Recent studies demonstrate that regional differences exist in both acute and chronic morphine along the gastrointestinal tract. While tolerance develops to the analgesic effects and upper gastrointestinal motility upon repeated morphine administration, tolerance does not develop in the colon with chronic opioids resulting in persistent constipation. Here, we review the mechanisms by which tolerance develops in the small but not the large intestine. The regional differences lie in the signaling and regulation of the μ-opioid receptor in the various segments of the gastrointestinal tract. The differential role of β-arrestin2 in tolerance development between central and enteric neurons defines the potential for therapeutic approaches in developing ligands with analgesic properties and minimal constipating effects.

The discovery and development of the N-substituted trans-3,4-dimethyl-4-(3'-hydroxyphenyl)piperidine class of pure opioid receptor antagonists

N-Substituted trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidines are a class of pure opioid receptor antagonists with a novel pharmacophore. This opioid receptor antagonist pharmacophore was used as a lead structure to design and develop several interesting and useful opioid receptor antagonists. In this review we describe: 1) early SAR studies that led to the discovery of LY255582 and analogues that are nonselective opioid receptor antagonists developed for the treatment of obesity; 2) the discovery and commercialization of LY246736 (alvimopan; ENTEREG®), a peripherally selective opioid receptor antagonist that accelerates the time to upper and lower GI recovery following surgeries that include partial bowel resection with primary anastomosis; and 3) the discovery and development of the potent and selective κ opioid receptor antagonist JDTic and analogues as potential pharmacotherapies for treating depression, anxiety, and substance abuse (nicotine, alcohol, and cocaine). In addition, the use of JDTic for obtaining the X-ray structure of the human κ opioid receptor is discussed.

Description of cardiovascular event rates in patients initiating chronic opioid therapy for noncancer pain in observational cohort studies in the US, UK, and Germany

INTRODUCTION

Previous observational studies in the US suggest that opioid analgesic use increases the risk of cardiovascular (CV) events. The current study provides additional background event rates for five prespecified CV outcomes of interest in patients from three countries.

METHODS

Three observational cohort studies were conducted in patients from the US (N = 17,604), the UK (N = 9,823), and Germany (N = 9,412). Patients were new opioid users who had undergone ≥6 months of chronic, continuous therapy. De-identified data were collated from electronic healthcare databases in the respective countries. Demographics, clinical characteristics, and opioid use were examined. Overall rates, prevalence rates in patients with established CV disease, and incidence rates in patients without established CV disease were determined for myocardial infarction (MI), stroke, transient ischemic attack, unstable angina, and congestive heart failure (CHF).

RESULTS

Cardiovascular disease at baseline was more prevalent in US and German patients. Back pain and depression were prevalent preexisting comorbidities. The majority of patients were using various weak opioids (based on receptor affinities), CV medications, and antidepressants. Overall rates by individual CV outcome per 1,000 patient-years by country were greatest for CHF (US 37.2, 95% CI 24.1-40.5), unstable angina (UK 8.2, 95% CI 7.0-9.6), and stroke (Germany 5.3, 95% CI 4.1-6.7). Overall rates for MI were: US, 10.7 (95% CI 9.1-12.5), UK, 6.7 (95% CI 5.6-8.0), and Germany, 2.7 (95% CI 1.9-3.7). Overall rates for each CV outcome, prevalence rates in patients with preexisting CV disease, and incidence rates in patients without established CV disease differed by country. Rates were higher in patients with preexisting CV disease.

CONCLUSIONS

CV risk for new opioid users with ≥6 months of therapy was increased in patients with established CV disease compared with those without established CV disease, and the risk for specific outcomes differed by country. Assessment of CV safety events of new therapies introduced to chronic opioid users should consider sample size and population heterogeneity in the design of an observational study.

Naloxegol for opioid-induced constipation in patients with noncancer pain

BACKGROUND

Opioid-induced constipation is common and debilitating. We investigated the efficacy and safety of naloxegol, an oral, peripherally acting, μ-opioid receptor antagonist, for the treatment of opioid-induced constipation.

METHODS

In two identical phase 3, double-blind studies (study 04, 652 participants; study 05, 700 participants), outpatients with noncancer pain and opioid-induced constipation were randomly assigned to receive a daily dose of 12.5 or 25 mg of naloxegol or placebo. The primary end point was the 12-week response rate (≥3 spontaneous bowel movements per week and an increase from baseline of ≥1 spontaneous bowel movements for ≥9 of 12 weeks and for ≥3 of the final 4 weeks) in the intention-to-treat population. The key secondary end points were the response rate in the subpopulation of patients with an inadequate response to laxatives before enrollment, time to first postdose spontaneous bowel movement, and mean number of days per week with one or more spontaneous bowel movements.

RESULTS

Response rates were significantly higher with 25 mg of naloxegol than with placebo (intention-to-treat population: study 04, 44.4% vs. 29.4%, P=0.001; study 05, 39.7% vs. 29.3%, P=0.02; patients with an inadequate response to laxatives: study 04, 48.7% vs. 28.8%, P=0.002; study 05, 46.8% vs. 31.4%, P=0.01); in study 04, response rates were also higher in the group treated with 12.5 mg of naloxegol (intention-to-treat population, 40.8% vs. 29.4%, P=0.02; patients with an inadequate response to laxatives, 42.6% vs. 28.8%, P=0.03). A shorter time to the first postdose spontaneous bowel movement and a higher mean number of days per week with one or more spontaneous bowel movements were observed with 25 mg of naloxegol versus placebo in both studies (P<0.001) and with 12.5 mg of naloxegol in study 04 (P<0.001). Pain scores and daily opioid dose were similar among the three groups. Adverse events (primarily gastrointestinal) occurred most frequently in the groups treated with 25 mg of naloxegol.

CONCLUSIONS

Treatment with naloxegol, as compared with placebo, resulted in a significantly higher rate of treatment response, without reducing opioid-mediated analgesia. (Funded by AstraZeneca; KODIAC-04 and KODIAC-05 ClinicalTrials.gov numbers, NCT01309841 and NCT01323790, respectively.).

Treatment of opioid-induced constipation: focus on the peripheral μ-opioid receptor antagonist methylnaltrexone

Most prescribed opioids exert their analgesic effects via activation of central μ-opioid receptors. However, μ-opioid receptors are also located in the gastrointestinal (GI) tract, and activation of these receptors by opioids can lead to GI-related adverse effects, in particular opioid-induced constipation (OIC). OIC has been associated with increased use of healthcare resources, increased healthcare costs, and decreased quality of life for patients. Nonpharmacologic (e.g., increased fiber uptake) and pharmacologic agents (e.g., laxatives) may be considered for the treatment and prevention of OIC. However, many interventions, such as laxatives alone, are generally insufficient to reverse OIC because they do not target the underlying cause of OIC, opioid activation of μ-opioid receptors in the GI tract. Therefore, there has been keen interest in antagonism of the μ-opioid receptor in the periphery to inhibit the effects of opioids in the GI tract. In this review, currently available pharmacologic therapies for the treatment and prevention of OIC are summarized briefly, with a primary focus on the administration of the peripheral μ-opioid receptor antagonist methylnaltrexone bromide in patients with OIC and advanced illness who are receiving palliative care. Also, clinical trial data of methylnaltrexone treatment in patients with OIC and other pain conditions (i.e., chronic noncancer pain and pain after orthopedic surgery) are reviewed. Data support that methylnaltrexone is efficacious for the treatment of OIC and has a favorable tolerability profile.

Clinical and economic burden of opioid use for postsurgical pain: focus on ventilatory impairment and ileus

Opioid-related adverse drug events (ORADEs) can have a significant impact on patient recovery after surgery. This review investigates the impact of two ORADEs, respiratory depression and postoperative ileus (POI), on clinical and economic outcomes. Opioid-induced ventilatory impairment is a potentially serious ORADE that can result in apnea and even death. The incidence of ventilatory impairment is approximately 1%, even among patients receiving opioids using patient-controlled analgesia. Costs are increased in patients treated with opioids who are at high risk of ventilatory impairment due to the need for more intensive monitoring from nursing staff and the use of alarmed monitoring equipment. Opioids, together with other factors, contribute to the development of POI through a direct effect on gut motility. Postoperative ileus has been shown to significantly increase hospital length of stay and cost of care. A key determinant of ileus development, as well as length of stay and costs, is postsurgical opioid dose. Data from a retrospective analysis show that a daily hydromorphone dose of 2 mg/day markedly increases the risk of POI. In addition, although the incidence of POI is reduced in patients who undergo laparoscopic surgery or hand-assisted laparoscopic surgery compared with open surgery, the reduction of POI can potentially be negated by excessive opioid use. Therefore, multimodal, opioid-sparing strategies should be explored and used to reduce severe ORADEs and improve outcomes in the surgical setting.

Design, synthesis, and biological evaluation of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)carboxamido]morphinan derivatives as peripheral selective μ opioid receptor Agents

Peripheral selective μ opioid receptor (MOR) antagonists could alleviate the symptoms of opioid-induced constipation (OIC) without compromising the analgesic effect of opioids. However, a variety of adverse effects were associated with them, partially due to their relatively low MOR selectivity. NAP, a 6β-N-4'-pyridyl substituted naltrexamine derivative, was identified previously as a potent and highly selective MOR antagonist mainly acting within the peripheral nervous system. The noticeable diarrhea associated with it prompted the design and synthesis of its analogues in order to study its structure-activity relationship. Among them, compound 8 showed improved pharmacological profiles compared to the original lead, acting mainly at peripheral while increasing the intestinal motility in morphine-pelleted mice (ED(50) = 0.03 mg/kg). The slight decrease of the ED(50) compared to the original lead was well compensated by the unobserved adverse effect. Hence, this compound seems to be a more promising lead to develop novel therapeutic agents toward OIC.

Opioids in preclinical and clinical trials

Since 1952, when Gates determined the stereo structure of morphine, numerous groups have focused on discovering a nonnarcotic opioid drug. Although several natural, semisynthetic, and synthetic opioid ligands (alkaloids and peptides) have been developed in clinical studies, very few were nonnarcotic opioid drugs. One of the most important studies in the opioid field appeared in 1976, when Martin and colleagues established types of opioid receptors (these are now classified into mu, delta, and kappa types). Later, Portoghese discovered a highly selective mu type opioid receptor antagonist, beta-funaltrexamine. This led to the finding that the mu type opioid receptor was correlated to drug dependence. Consequently, delta, and particularly kappa, opioid agonists were expected to lead to ideal opioid drugs. Moreover, opioid antagonists were evaluated for the treatment of symptoms related to undesirable opioid system activation. In this chapter, we provide a short survey of opioid ligands in development and describe the discovery of the two most promising drugs, TRK-851 and TRK-820 (nalfurafine hydrochloride).

Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states

Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.

An Evaluation of Alvimopan Use as Part of Perioperative Management of Patients Undergoing Laparoscopic Small and Large Bowel Resections

Objective

Delayed gastrointestinal (GI) recovery (postoperative ileus) is a risk for patients undergoing bowel resection (BR) and presents clinical challenges including prolonged hospital length of stay (LOS) and increased postoperative morbidity. Alvimopan, an oral, peripherally acting mu-opioid receptor antagonist, is the first therapy approved to accelerate GI recovery after BR. Published data have described alvimopan use in open BR. In contrast, this study focused on laparoscopic BR.

Methods

Historic data were retrospectively collected and alvimopan data were prospectively collected from 1 surgeon at our facility. Adults undergoing laparoscopic partial small or large BR with primary anastamosis scheduled to receive intravenous, opioid-based, patient-controlled analgesia were eligible. Pregnancy, opioid analgesic on the home medication reconciliation form, complete bowel obstruction, colostomy or ileostomy creation, and unplanned surgery were exclusion criteria. All patients were uniformly managed with a standardized accelerated postoperative care pathway to facilitate GI recovery. LOS, time to first bowel movement (BM), 30-day readmission rate, and the cost were evaluated. Data were analyzed using Pearson chi-square and independent samples t tests.

Results

Thirty-nine alvimopan and 56 historic cohort patients were included. Time to first BM was reduced by 1.2 days and LOS was reduced by 1.1 days (both P < .001) in the alvimopan cohort compared with control. Overall variable cost data were reduced by $1,368 in the alvimopan cohort. Readmission rates were low and comparable.

Conclusions

Laparoscopic surgery can decrease LOS compared with open BR; however, alvimopan use at our facility reduced LOS and time to BM while remaining cost-effective in this patient population.

Opioid antagonists for prevention and treatment of opioid-induced gastrointestinal effects

PURPOSE OF REVIEW

The therapeutic action of opioid analgesics is compromised by peripheral adverse effects, among which constipation is the most disabling as laxatives often fail to provide satisfactory relief. This review highlights recent advances in the specific control of opioid-induced constipation by opioid receptor antagonists with limited systemic bioavailability or a peripherally restricted site of action.

RECENT FINDINGS

The specific management of opioid-induced bowel dysfunction is currently based on three drug entities: oral alvimopan for the shortening of postoperative ileus associated with opioid-induced pain control after bowel resection, subcutaneous methylnaltrexone for the reduction of opioid-induced constipation in patients with advanced illness, and a fixed combination of oral prolonged-release naloxone with prolonged-release oxycodone for the treatment of noncancer and cancer pain. All three drug entities have been shown to attenuate opioid-induced motor stasis in the gut with a favorable adverse effect profile, while the analgesic effect of opioids remains unabated.

SUMMARY

The availability of opioid receptor antagonists with restricted access to the central nervous system provides a novel opportunity to specifically control opioid-induced constipation and other peripheral adverse effects of opioid analgesics. Further studies are needed to evaluate the long-term efficacy, safety and cost-effectiveness of this approach.

Pharmacologic management of chronic constipation

Chronic constipation is a common digestive problem in North America, with significant psychosocioeconomic implications. Dietary and lifestyle measures and low-cost traditional over-the-counter laxatives are usually the first line of therapy but help only half of the patients. Several newer agents that act by increasing colonic peristalsis, altering colonic secretion, and/or antagonizing enteric opioid receptors have been developed that are effective in treating constipation and its related symptoms as well as improving quality of life. This article focuses on the pharmacology of traditional and newer agents for the treatment of constipation.

Postoperative ileus: Impact of pharmacological treatment, laparoscopic surgery and enhanced recovery pathways

Almost all patients develop postoperative ileus (POI) after abdominal surgery. POI represents the single largest factor influencing length of stay (LOS) after bowel resection, and has great implications for patients and resource utilization in health care. New methods to treat and decrease the length of POI are therefore of great importance. During the past decade, a substantial amount of research has been performed evaluating POI, and great progress has been made in our understanding and treatment of POI. Laparoscopic procedures, enhanced recovery pathways and pharmacologic treatment have been introduced. Each factor has substantially contributed to decreasing the length of POI and thus LOS after bowel resection. This editorial outlines resource utilization of POI, normal physiology of gut motility and pathogenesis of POI. Pharmacological treatment, fast track protocols and laparoscopic surgery can each have significant impact on pathways causing POI. The optimal integration of these treatment options continues to be assessed in prospective studies.

Synthesis and opioid activity of enantiomeric N-substituted 2,3,4,4a,5,6,7,7a-octahydro-1H-benzofuro[3,2-e]isoquinolines

A series of enantiomeric N-substituted 2,3,4,4a,5,6,7,7a-octahydro-1H-benzofuro[3,2-e]isoquinolines was synthesized. The (-)-enantiomers had much greater kappa-, mu-, and delta-opioid receptor binding affinity than the corresponding (+)-enantiomers. Compounds (-)-1a, (-)-1b, and (-)-1c displayed subnanomolar binding affinity for the mu-receptor, and (-)-1b had a high affinity for the kappa-receptor. Compound (-)-1a was a mu-partial agonist and kappa-antagonist. Compound (-)-1b was a potent neutral mu-antagonist (K(d) = 0.22 nM) and a kappa-partial agonist.