Emerging pharmacologic options for treating postoperative ileus

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.

Enhanced Recovery after Surgery Protocol Accelerates Recovery of Lumbar Disc Herniation among Elderly Patients Undergoing Discectomy via Promoting Gastrointestinal Function

This study aimed to analyze the effect of the enhanced recovery after surgery (ERAS) protocol on the recovery of gastrointestinal function in patients with lumbar disc herniation after discectomy. A total of 179 patients with lumbar disc herniation were randomly divided into the ERAS and non-ERAS groups. The non-ERAS group received routine nursing, and the ERAS group received ERAS strategy. The two groups were compared for general recovery indicators such as postoperative hemoglobin and prealbumin, satisfaction, and length of hospital stay. Gastrointestinal function was also evaluated, such as postoperative feeding time, intestinal chirping recovery time, intestinal exhaust gas recovery time, and complications such as ileus, nausea, and vomiting. The satisfaction of patients in the ERAS group (86.15 ± 2.43) was significantly higher than that in the non-ERAS group (77.19 ± 3.32), and the difference was statistically significant (P < 0.05). The average time of eating in the ERAS group was 2.27 h after surgery. In addition, the amount of eating in the ERAS group was significantly better than that in the non-ERAS group, and the difference was statistically significant. In the ERAS group, intestinal chirping recovery time recovered to normal time, and exhaust recovery time and average defecation time were significantly shorter than those in the non-ERAS group. In the ERAS group, the average amount of hemoglobin and prealbumin decreased 3 days after operation, which was significantly lower than that in the non-ERAS group. To sum up, ERAS has an evident effect on the recovery of gastrointestinal function after discectomy of disc herniation, which can promote the recovery of patients.

Opioid-Induced Constipation and Bowel Dysfunction: A Clinical Guideline

OBJECTIVE

To formulate timely evidence-based guidelines for the management of opioid-induced bowel dysfunction.

SETTING

Constipation is a major untoward effect of opioids. Increasing prescription of opioids has correlated to increased incidence of opioid-induced constipation. However, the inhibitory effects of opioids are not confined to the colon, but also affect higher segments of the gastrointestinal tract, leading to the coining of the term "opioid-induced bowel dysfunction."

METHODS

A literature search was conducted using Medline, EMBASE, and EMBASE Classic, and the Cochrane Central Register of Controlled Trials. Predefined search terms and inclusion/exclusion criteria were used to identify and categorize relevant papers. A series of statements were formulated and justified by a comment, then labeled with the degree of agreement and their level of evidence as judged by the Strength of Recommendation Taxonomy (SORT) system.

RESULTS

From a list of 10,832 potentially relevant studies, 33 citations were identified for review. Screening the reference lists of the pertinent papers identified additional publications. Current definitions, prevalence, and mechanism of opioid-induced bowel dysfunction were reviewed, and a treatment algorithm and statements regarding patient management were developed to provide guidance on clinical best practice in the management of patients with opioid-induced constipation and opioid-induced bowel dysfunction.

CONCLUSIONS

In recent years, more insight has been gained in the pathophysiology of this "entity"; new treatment approaches have been developed, but guidelines on clinical best practice are still lacking. Current knowledge is insufficient regarding management of the opioid side effects on the upper gastrointestinal tract, but recommendations can be derived from what we know at present.

Cost and efficacy examination of alvimopan for the prevention of postoperative ileus

Opioid analgesics exacerbate ileus through peripheral μ-opioid receptor action. Alvimopan, a μ-opioid receptor antagonist, has been proposed to alleviate postoperative ileus, leading to decreased time to return of gastrointestinal function and hospital discharge. As opioid-induced motility issues are only one factor affecting postoperative ileus, continued examination of the cost of the use and efficacy of the drug is needed. Data for this study were collected retrospectively from the charts of 55 patients who received an anastomosis and were given alvimopan at Morristown Medical Center between 2010 and 2013 as well as from 58 appropriately matched controls. The billing record and chart for each patient was examined, and information on total hospital charges, age, sex, body mas index, primary diagnosis, procedure type, length of stay (days), time to return of bowel function (hours), and outcomes were recorded for analysis. No difference between patients given alvimopan and controls was observed for the length of hospital stay (4.6 vs 4.8 days) or for time to return of bowel function (68.5 vs 67.3 hours). Total hospital charges were higher for treated patients (p=0.0080), averaging $48 705.15 and $41 068.80, respectively. Alvimopan was not associated with improved clinical outcome but was associated with an increase in hospital charges within this population.

Prevention of Paralytic Ileus Utilizing Alvimopan Following Spine Surgery

Postoperative ileus affects a substantial proportion of patients undergoing elective spine surgery, especially in cases of spinal deformity correction and where an anterior lumbar approach is utilized. Though the first line of treatment for postoperative ileus is conservative management, recent advances in pharmacology have yielded promising options for both treatment and prevention. We report a case of a patient who underwent a two-stage posterior spinal fusion. The patient suffered with a severe, prolonged ileus after her initial surgery. To prevent ileus following her second spinal surgery, alvimopan (a µ-opioid receptor antagonist) was administered and she had a rapid return of bowel function with no signs of ileus. Alvimopan, has been shown to reduce the rate of ileus in colorectal surgery patients, and may be useful for preventing ileus in high-risk orthopedic and spine surgery patients, although prospective studies will be needed to test this hypothesis.

Safety, tolerability, pharmacokinetics, and pharmacodynamic effects of naloxegol at peripheral and central nervous system receptors in healthy male subjects: A single ascending-dose study

This randomized, double-blind, placebo-controlled, ascending-dose, crossover study evaluated single oral doses of naloxegol (NKTR-118; 8, 15, 30, 60, 125, 250, 500, and 1000 mg), a PEGylated derivative of naloxone, for safety and tolerability, antagonism of peripheral and central nervous system (CNS) effects of intravenous morphine, and pharmacokinetics. Healthy men were randomized 1:1 to naloxegol or naloxegol-matching placebo administered with morphine and lactulose in a 2-period crossover design. Periods were separated by a 5- to 7-day washout. Assessments included safety, tolerability, orocecal transit time (OCTT), pupillary miosis, and pharmacokinetics. The study was completed by 46 subjects. The most common adverse events were somnolence, dizziness, headache, and nausea. Greater reversal of morphine-induced delay in OCTT occurred with increasing naloxegol dose, demonstrating dose-ordered antagonism of morphine's peripheral gastrointestinal effects. Forty-four subjects showed no reversal of pupillary miosis; 2 showed potential partial reversal at 250 and 1000 mg, indicating negligible antagonism of morphine's CNS effects at doses ≤ 125 mg. Rapid absorption, linear pharmacokinetics up to 1000 mg, and low to moderate between-subject pharmacokinetic variability was observed. The pharmacokinetics of morphine or its glucuronide metabolites were unaltered by concurrent naloxegol administration. Naloxegol was generally safe and well tolerated at single doses up to 1000 mg.

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.

Emerging treatments in neurogastroenterology: a multidisciplinary working group consensus statement on opioid-induced constipation

BACKGROUND

Opioids are effective for acute and chronic pain conditions, but their use is associated with often difficult-to-manage constipation and other gastrointestinal (GI) effects due to effects on peripheral μ-opioid receptors in the gut. The mechanism of opioid-induced constipation (OIC) differs from that of functional constipation (FC), and OIC may not respond as well to most first-line treatments for FC. The impact of OIC on quality of life (QoL) induces some patients to decrease or stop their opioid therapy to relieve or avoid constipation.

PURPOSE

At a roundtable meeting on OIC, a working group developed a consensus definition for OIC diagnosis across disciplines and reviewed current OIC treatments and the potential of treatments in development. By consensus, OIC is defined as follows: 'A change when initiating opioid therapy from baseline bowel habits that is characterized by any of the following: reduced bowel movement frequency, development or worsening of straining to pass bowel movements, a sense of incomplete rectal evacuation, or harder stool consistency'. The working group noted the prior validation of a patient response outcome and end point for clinical trials and recommended future efforts to create treatment guidelines and QoL measures specific for OIC. Details from the working group's discussion and consensus recommendations for patient care and research are presented in this article.

Management of postoperative ileus

Postoperative ileus, a temporary cessation in bowel motility, is a common and significant complication of major surgery. Consequences of postoperative ileus include increased patient discomfort, delayed time to adequate nutrition, prolonged length of stay, and increased cost to the patient and healthcare system. The traditional, multi-modal approach to the resolution of postoperative ileus includes opioid minimization, early ambulation, and early feeding. Newer medications, such as methlynaltrexone and alvimopan (which are peripherally acting mu opioid receptor antagonists), have become available and have proven beneficial for use with postoperative ileus.

Resolution of opioid-induced postoperative ileus in a newborn infant after methylnaltrexone

Transient impairment of bowel function is a frequent and distressing problem in neonates on opioid-induced analgesia. Methylnaltrexone, a peripheral-acting μ-opioid receptor antagonist, has been studied in adults for the treatment of opioid-induced constipation in advanced illness and has been suggested as a promising therapeutic concept for reducing postoperative ileus. Here, we report on a newborn infant on fentanyl analgesia after major abdominal surgery with aggravated ileus. After 8 days of quiescent bowel, the patient's intestinal dysmotility resolved within 15 minutes after intravenous administration of methylnaltrexone (0.15 mg/kg body weight). Methylnatrexone was repeated daily until cessation of fentanyl administration. There were no signs of pain or opioid withdrawal.

Systematic review and meta-analysis of chewing-gum therapy in the reduction of postoperative paralytic ileus following gastrointestinal surgery

BACKGROUND

Postoperative ileus has long been considered an inevitable consequence of gastrointestinal surgery. It prolongs hospital stay, increases morbidity, and adds to treatment costs. Chewing is a form of sham feeding reported to stimulate bowel motility. This analysis examines the value of chewing-gum therapy in treatment of postoperative ileus.

METHODS

A search for randomized, controlled trials studying elective gastrointestinal surgery was undertaken using MEDLINE, Embase, Cochrane Controlled Trials Register, and reference lists. Outcomes were extracted including time to first flatus and bowel motion, length of stay, and complications. Statistical analysis was undertaken using the weighted mean difference (WMD) and random-effects model with 95% confidence intervals (CI).

RESULTS

Seven studies with 272 patients were included. For time to first flatus the analysis favored treatment with a WMD of 12.6 h (17%) reduction (95% CI -21.49 to -3.72; P = 0.005). For time to first bowel motion, treatment was favored with a WMD of 23.11 h (22%) reduction (95% CI -34.32 to -11.91; P < 0.001). For length of stay, the analysis showed a nonsignificant trend toward treatment with WMD of 23.88 h (12%) reduction (95% CI -53.29 to +5.53; P = 0.11). There were no significant differences in complication rates.

CONCLUSIONS

Chewing-gum therapy following open gastrointestinal surgery is beneficial in reducing the period of postoperative ileus, although without a significant reduction in length of hospital stay. These outcomes are not significant for laparoscopic gastrointestinal surgery.

Drug-induced acute liver failure and gastrointestinal complications

The objective of this article is to describe adverse drug events related to the liver and gastrointestinal tract in critically ill patients. PubMed and other resources were used to identify information related to drug-induced acute liver failure, gastrointestinal hypomotility, constipation, diarrhea, gastrointestinal bleeding, and pancreatitis in critically ill patients. This information was reviewed, and data regarding pathophysiology, common drug causes, and guidelines for prevention and management were collected and summarized. In cases in which data in critically ill patients were unavailable, data were extrapolated from other patient populations. Drug-induced acute liver failure can be caused by many drugs routinely used in the intensive care unit and may be associated with significant morbidity and mortality. Drug-related hypomotility and constipation and drug-related diarrhea are reported with many drugs, and these are common adverse drug events in critically ill patients that can substantially complicate the care of these patients. Drug-induced gastrointestinal bleeding and drug-induced pancreatitis occur less frequently, can range in disease severity, and can be associated with morbidity and mortality. Many drugs used in critically ill patients are associated with adverse drug events related to the liver and gastrointestinal tract. Critical care clinicians should be aware of common drug causes of drug-induced acute liver failure, gastrointestinal hypomotility, constipation, diarrhea, gastrointestinal bleeding, and pancreatitis, and should be familiar with the prevention and management of these diverse conditions.

Pathogenesis and management of postoperative ileus

Postoperative ileus (POI) is a predictable delay in gastrointestinal (GI) motility that occurs after abdominal surgery. Probable mechanisms include disruption of the sympathetic/parasympathetic pathways to the GI tract, inflammatory changes mediated over multiple pathways, and the use of opioids for the management of postoperative pain. Pharmacologic treatment of postoperative ileus continues to be problematic as most agents are unreliable and unsubstantiated with robust clinical trials. The selective opioid antagonist alvimopan has shown promise in reducing POI, but needs more rigorous investigation. Clinician interventions proven to be of benefit include laparoscopy, thoracic epidural anesthesia, avoidance of opioids, and early feeding. Early ambulation may also contribute to early resolution of POI; however, routine nasogastric decompression plays no role and may increase complications. Multimodal care plans remain the mainstay of treatment for POI.

Postoperative ileus: it costs more than you expect

BACKGROUND

The clinical impact of postoperative ileus (POI) after colectomy is difficult to quantify financially because of administrative coding limitations. Accurate data are important to allow pharmaco-economic analysis of methods aimed at reducing POI. The aim of this study was to assess the financial impact of POI for the 30-day episode of care for colectomy.

STUDY DESIGN

We reviewed all colectomy patients at our institution from July 2007 to June 2008. Primary POI was defined as more than three episodes of emesis with return to NPO diet status and/or reinsertion of nasogastric tube; secondary POI was associated with intraabdominal complications. Readmission for gastrointestinal failure was defined as delayed POI (no radiologic or surgical identification of small bowel obstruction). All other complications requiring readmission were grouped together for analysis. Data reviewed included primary admission and readmission costs, reason for readmission, intervention, index and total length of stay, narcotic use, time to ambulation, and time to enteral feeds.

RESULTS

One hundred eighty-six colectomies were eligible for analysis, with 45 cases (38 primary and 7 secondary) of POI during the index admission. The total cost was significantly higher for patients with POI ($16,612 versus $8,316; p < 0.05). However, readmission costs were not statistically different for delayed POI and other complications ($3,546 versus $6,705).

CONCLUSIONS

POI occurred in 24% (84% primary) of colectomy patients and disproportionately affected cost at the index admission. Interestingly, delayed POI was similar in cost to readmission for other serious adverse surgical complications.

Recent Advances in Pharmacotherapy

Many unique and clinically important medications were approved by the Food and Drug Administration from December 2007 through May 2008 for various conditions encountered in an internal medicine setting. These new treatments dramatically vary in their targeted body system and include agents for the cardiovascular system (nebivolol), central nervous system (desvenlafaxine), gastrointestinal tract (certolizumab, methylnaltrexone, and alvimopan), immunological function (etravirine), and metabolic function (sapropterin). This article discusses medications by their respective body system. Each review is comprised of an overview of the Food and Drug Administration–approved indication and the drug’s role in treatment of that disease state. Current dosing guidance, clinical efficacy and clinically relevant adverse drug reactions, drug interactions, contraindications, and precautions are also presented. This review is designed to focus on the new molecular entities and biological approvals clinicians may potentially encounter in an internal medicine practice.

Novel opioid antagonists for opioid-induced bowel dysfunction and postoperative ileus

Peripherally acting mu-opioid receptor antagonists methylnaltrexone and alvimopan are a new class of drugs designed to reverse opioid-induced side-effects on the gastrointestinal system without compromising pain relief. This article gives an overview of the pharmacology, the efficacy, and adverse effects of these drugs. Both compounds seem to be generally well tolerated and effective for the treatment of opioid-related bowel dysfunction and postoperative ileus. Methylnaltrexone recently received approval by the US Food and Drug Administration (FDA) and the European Medicines Agency for treatment of opioid-related bowel dysfunction in patients with advanced illness. Alvimopan was recently approved by the FDA for treatment of postoperative ileus, but the use of the drug is restricted to inpatients because it has been associated with an increased rate of myocardial infarction. Further research should assess the effectiveness and safety of these drugs in clinical practice.

Safety and efficacy update: Alvimopan in postoperative ileus

Postoperative ileus (POI) in patients undergoing abdominal surgery is associated with significant morbidity. In 2008, alvimopan (Entereg®) was approved by the Food and Drug Administration (FDA), and is the only available POI therapy in the United States for patients undergoing bowel resection. Data from preclinical studies demonstrate that alvimopan and its primary metabolite, ADL 08-0011, behave as potent μ. opioid receptor antagonists. In animals, alvimopan and ADL 08-0011 attenuate opioid agonist-induced reductions in gastrointestinal (GI) transit. Higher doses of alvimopan are required to inhibit opioid-induced analgesia as a result of its inability to penetrate the central nervous system (CNS). ADL 08-0011 is also peripherally selective, although to a lesser degree than alvimopan. In multiple species, including humans, alvimopan has low oral bioavailability, while ADL 08-0011, following its generation by human gut microflora, is more readily absorbed and achieves higher exposures. Three Phase 2 and five Phase 3 clinical trials have been conducted to investigate the efficacy and tolerability of alvimopan in patients undergoing bowel resection. An additional Phase 3 study was conducted in hysterectomy patients. In the majority of the studies, statistically significant, and clinically meaningful, acceleration of GI recovery has been demonstrated. Consistent with animal data, alvimopan has no effect on opioid agonist-induced analgesia in healthy human subjects and POI patients. Clinical experience to date in POI patients indicates that alvimopan is well tolerated when used according to its approved dosing regimen (12 mg b.i.d. for up to 7 days). In this article, the preclinical and clinical properties of alvimopan are reviewed.

Methylnaltrexone, a new peripherally acting mu-opioid receptor antagonist being evaluated for the treatment of postoperative ileus

Postoperative ileus (POI), a transient impairment of bowel function, is considered an inevitable response after open abdominal surgery. It leads to significant patient morbidity and increased hospital costs and length of stay. The pathophysiology is multifactorial, involving neurogenic, hormonal, inflammatory and pharmacologic mediators. Several treatments have been shown to reduce the duration of POI, and a multimodal approach combining several of these interventions seems to be the most effective treatment option. Various drug therapies have been evaluated for the treatment of POI, although most have not shown any benefit. Peripherally active mu-opioid receptor antagonists are a new class of compounds that selectively block the peripheral (i.e., gastrointestinal [GI]) effects of opioids while preserving centrally mediated analgesia. Recently, alvimopan was approved in the US for the treatment of POI after abdominal surgery with bowel resection. Methylnaltrexone is a peripherally active mu-opioid receptor antagonist that has been shown to antagonize the inhibitory effects of opioids on GI transit without impairing analgesia. Phase II data indicated that methylnaltrexone was effective for improving GI recovery, reducing POI and shortening the time to discharge readiness in patients who underwent segmental colectomy. Two Phase III trials have been completed, and one is underway at present. Preliminary results from the two completed trials indicate that methylnaltrexone was not better than placebo for the primary or secondary outcomes. Further analyses of these data, clinical trial designs and the various dosage forms are necessary to determine the potential role of methylnaltrexone in the treatment of POI.

Natural products to drugs: natural product-derived compounds in clinical trials

Natural product and natural product-derived compounds that are being evaluated in clinical trials or are in registration (as at 31st December 2007) have been reviewed, as well as natural product-derived compounds for which clinical trials have been halted or discontinued since 2005. Also discussed are natural product-derived drugs launched since 2005, new natural product templates and late-stage development candidates.