The constipation-inducing potential of morphine and transdermal fentanyl

Medical Management of Inoperable Malignant Bowel Obstruction

OBJECTIVE

To review medical management of inoperable malignant bowel obstruction.

DATA SOURCES

A literature review using PubMed and MEDLINE databases searching malignant bowel obstruction, etiology, types, pathophysiology, medical, antisecretory, anti-inflammatory, antiemetic drugs, analgesics, promotion of emptying, prevention of infection, anticholinergics, somatostatin analogs, gastric antisecretory drugs, prokinetic agents, glucocorticoid, opioid analgesics, antibiotics, enema, and adverse effects.

STUDY SELECTION AND DATA EXTRACTION

Randomized or observational studies, cohorts, case reports, or reviews written in English between 1983 and November 2020 were evaluated.

DATA SYNTHESIS

Malignant bowel obstruction (MBO) commonly occurs in patients with advanced or recurrent malignancies and severely affects the quality of life and survival of patients. Its management remains complex and variable. Medical management is the cornerstone of MBO treatment, with the goal of reducing distressing symptoms and optimizing quality of life. Until now, there has been neither a standard clinical approach nor registered medications to treat patients with inoperable MBO.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review provides information on the etiology, type and pathophysiology, and medical treatment of MBO and related adverse reactions of the drugs commonly used, which can greatly assist clinicians in making clinical decisions when treating MBO.

CONCLUSIONS

Published research shows that medical management of MBO mainly consists of antisecretory, anti-inflammatory strategies, controlling vomiting and pain, promoting emptying, preventing infection, and combination therapy. Being knowledgeable about the most current treatment options, the related adverse effects, and the evidence supporting different practices is critical for clinicians to provide individualized medical therapy for MBO patients.

Nanoconjugated NAP as a Potent and Periphery Selective Mu Opioid Receptor Modulator To Treat Opioid-Induced Constipation

Opioids are the mainstay for cancer and noncancer pain management. However, their use is often associated with multiple adverse effects. Among them, the most common and persistent one is probably opioid-induced constipation (OIC). Periphery selective opioid antagonists may alleviate the symptoms of OIC without compromising the analgesic effects of opioids. Recently our laboratories have identified one novel lead compound, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)acetamido]morphinan (NAP), as a peripherally selective mu opioid receptor ligand carrying subnanomolar affinity to the mu opioid receptor and over 100-folds of selectivity over both the delta and kappa opioid receptors, with reasonable oral availability and half-life, and potential to treat OIC. Nanoparticle-based drug delivery systems are now widely considered due to their technological advantages such as good stability, high carrier capacity, low therapeutic side effects, etc. Herein we report nanoparticle supported NAP as a potential candidate for OIC treatment with improved peripheral selectivity over the original lead compound NAP.

Laxatives for the management of constipation in people receiving palliative care

BACKGROUND

This article describes the second update of a Cochrane review on the effectiveness of laxatives for the management of constipation in people receiving palliative care. Previous versions were published in 2006 and 2010 where we also evaluated trials of methylnaltrexone; these trials have been removed as they are included in another review in press. In these earlier versions, we drew no conclusions on individual effectiveness of different laxatives because of the limited number of evaluations. This is despite constipation being common in palliative care, generating considerable suffering due to the unpleasant physical symptoms and the availability of a wide range of laxatives with known differences in effect in other populations.

OBJECTIVES

To determine the effectiveness and differential efficacy of laxatives used to manage constipation in people receiving palliative care.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library), MEDLINE, EMBASE, CINAHL and Web of Science (SCI & CPCI-S) for trials to September 2014.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating laxatives for constipation in people receiving palliative care.

DATA COLLECTION AND ANALYSIS

Two authors assessed trial quality and extracted data. The appropriateness of combining data from the studies depended upon clinical and outcome measure homogeneity.

MAIN RESULTS

We identified five studies involving the laxatives lactulose, senna, co-danthramer, misrakasneham, docusate and magnesium hydroxide with liquid paraffin. Overall, the study findings were at an unclear risk of bias. As all five studies compared different laxatives or combinations of laxatives, it was not possible to perform a meta-analysis. There was no evidence on whether individual laxatives were more effective than others or caused fewer adverse effects.

AUTHORS' CONCLUSIONS

This second update found that laxatives were of similar effectiveness but the evidence remains limited due to insufficient data from a few small RCTs. None of the studies evaluated polyethylene glycol or any intervention given rectally. There is a need for more trials to evaluate the effectiveness of laxatives in palliative care populations. Extrapolating findings on the effectiveness of laxatives evaluated in other populations should proceed with caution. This is because of the differences inherent in people receiving palliative care that may impact, in a likely negative way, on the effect of a laxative.

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.

Pharmacological treatment of bowel obstruction in cancer patients

INTRODUCTION

Malignant bowel obstruction (MBO) is a common complication of advanced cancer, occurring most frequently in gynaecological and colorectal cancer. Its management remains complex and variable. This is in part due to the lack of evidence-based guidelines for the clinicians involved. Although surgery should be considered the primary treatment, this may not be feasible in patients with a poor performance status or advanced disease. Advances have been made in the medical management of MBO which can lead to a considerable improvement in symptom management and overall quality of life.

AREAS COVERED

This review emphasizes the importance of a prompt diagnosis of MBO with early introduction of pharmacological agents to optimize symptom control. The authors summarize the treatment options available for bowel obstruction in those patients for whom surgical intervention is not a feasible option. The authors also explore the complexities involved in the introduction of parenteral hydration and total parenteral nutrition in this group of patients.

EXPERT OPINION

It is not always easy to distinguish reversible from irreversible bowel obstruction. Early and aggressive management with the introduction of pharmacological agents including corticosteroids, octreotide and anti-cholinergic agents have the potential to maintain bowel patency, and allow for more rapid recovery of bowel transit. A combination of analgesics, anti-emetics and anti-cholinergics with or without anti-secretory agents can successfully improve symptom control in patients with irreversible bowel obstruction.

Laxatives or methylnaltrexone for the management of constipation in palliative care patients

BACKGROUND

Constipation is common in palliative care; it can generate considerable suffering due to the unpleasant physical symptoms. In the first Cochrane Review on effectiveness of laxatives for the management of constipation in palliative care patients, published in 2006, no conclusions could be drawn because of the limited number of evaluations. This article describes the first update of this review.

OBJECTIVES

To determine the effectiveness of laxatives or methylnaltrexone for the management of constipation in palliative care patients.

SEARCH STRATEGY

We searched databases including MEDLINE and CENTRAL (The Cochrane Library) in 2005 and in the update to August 2010.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating laxatives for constipation in palliative care patients. In the update we also included RCTs on subcutaneous methylnaltrexone; an opioid-receptor antagonist that is now licensed for the treatment of opioid-induced constipation in palliative care when response to usual laxative therapy is insufficient.

DATA COLLECTION AND ANALYSIS

Two authors assessed trial quality and extracted data. The appropriateness of combining data from the studies depended upon clinical and outcome measure homogeneity.

MAIN RESULTS

We included seven studies involving 616 participants; all under-reported methodological features. In four studies the laxatives lactulose, senna, co-danthramer, misrakasneham, and magnesium hydroxide with liquid paraffin were evaluated. In three methylnaltrexone.In studies comparing the different laxatives evidence was inconclusive. Evidence on subcutaneous methylnaltrexone was clearer; in combined analysis (287 participants) methylnaltrexone, in comparison with a placebo, significantly induced laxation at 4 hours (odds ratio 6.95; 95% confidence interval 3.83 to 12.61). In combined analyses there was no difference in the proportion experiencing side effects, although participants on methylnaltrexone suffered more flatulence and dizziness. No evidence of opioid withdrawal was found. In one study severe adverse events, commonly abdominal pain, were reported that were possibly related to methylnaltrexone. A serious adverse event considered to be related to the methylnaltrexone also occurred; this involved a participant having severe diarrhoea, subsequent dehydration and cardiovascular collapse.

AUTHORS' CONCLUSIONS

The 2010 update found evidence on laxatives for management of constipation remains limited due to insufficient RCTs. However, the conclusions of this update have changed since the original review publication in that it now includes evidence on methylnaltrexone. Here it found that subcutaneous methylnaltrexone is effective in inducing laxation in palliative care patients with opioid-induced constipation and where conventional laxatives have failed. However, the safety of this product is not fully evaluated. Large, rigorous, independent trials are needed.

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

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

Rates of adverse events of long-acting opioids in a state Medicaid program

BACKGROUND

Despite widespread use and emerging safety concerns, data on the comparative safety and effectiveness of long-acting opioid (LAO) analgesics are weak.

OBJECTIVE

To compare rates of adverse events among patients newly prescribed an LAO.

METHODS

A retrospective observational cohort study using Medicaid administrative claims data was conducted examining time until first adverse outcome among patients with new prescriptions for methadone, extended-release (ER) oxycodone, ER morphine, or transdermal fentanyl. Adverse outcomes included emergency department (ED) encounters or hospitalizations for opioid-related adverse events, all-cause ED encounters or hospitalizations, death, and diagnoses for opioid-related adverse effects. Cox proportional hazards models were used to adjust for a variety of measured covariates overall and within subgroups of patients with and without cancer.

RESULTS

This study included 5684 subjects. Patients prescribed ER oxycodone were 55[corrected]% less likely (adjusted hazard ratio [HR] 0.45; 95% CI 0.26 to 0.77) to experience an ED or hospitalization involving an opioid-related adverse event, 23% lower risk of hospitalization (adjusted HR 0.77; 95% CI 0.66 to 0.91), 41% lower risk of constipation (adjusted HR 0.59; 95% CI 0.35 to 1.00), and a 29% lower risk of death (adjusted HR 0.71; 95% CI 0.54 to 0.94) compared with those prescribed ER morphine. Among subjects with noncancer pain, fentanyl was associated with a higher risk of ED encounters (adjusted HR 1.27; 95% CI 1.02 to 1.59) and methadone was associated with a greater risk of overdose symptoms (adjusted HR 1.57; 95% CI 1.03 to 2.40) compared with ER morphine.

CONCLUSIONS

Our results support a modest safety advantage with ER oxycodone compared with ER morphine. Among subjects with noncancer pain, fentanyl and methadone were associated with an increased risk of an adverse event compared with ER morphine. Additional studies are needed to confirm our findings and further clarify risks associated with different LAOs.

Laxatives for the management of constipation in palliative care patients

BACKGROUND

Constipation is a common problem for palliative care patients which can generate considerable suffering for patients due to both the unpleasant physical symptoms and psychological preoccupations that can arise. There is uncertainty about the 'best' management of constipation in palliative care patients and variation in practice between palliative care settings.

OBJECTIVES

To determine the effectiveness of laxative administration for the management of constipation in palliative care patients, and the differential efficacy of the laxatives used to manage constipation.

SEARCH STRATEGY

We searched The Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue four, 2005), MEDLINE (1966 to January 2005), EMBASE (1980 to January 2005), CANCERLIT, PUBMED, Science Citation Index, CINAHL, The Cochrane Library, SIGLE, NTIS, DHSS-DATA, Dissertation Abstracts, Index to Scientific and Technical Proceedings and NHS-NRR and reference lists of articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing laxatives for constipation in palliative care patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted patient-reported data measuring changes in stool frequency and ease of passing stools, using objective and validated scales. Tolerance or adverse effects of laxatives used were also sought. The appropriateness of synthesizing data from the controlled trials depended upon the clinical and statistical homogeneity of studies identified. If the controlled trials were homogeneous, a meta-analysis would be attempted.

MAIN RESULTS

Four trials involving 280 people were included. Between these trials, the laxatives lactulose; senna; danthron combined with poloxamer (Co-danthramer); Misrakasneham; magnesium hydroxide combined with liquid paraffin (Milpar) were evaluated. All four trials included number and frequency of bowel movements and relative ease of defecation as part of the assessment of laxative efficacy. All of the laxatives demonstrated a limited level of efficacy, although a significant number of participants required rescue laxatives in each of the studies. The only significantly different treatments were in the trial where lactulose plus senna were more effective than danthron combined with poloxamer. Patient preference did not favour either treatment option. Other related systematic reviews have similarly identified that there is a lack of evidence to support the use of one laxative, or combination of laxatives, over another.

AUTHORS' CONCLUSIONS

The treatment of constipation in palliative care is based on inadequate experimental evidence, such that there are insufficient RCT data. Recommendations for laxative use can be related to costs as much as to efficacy. There have been few comparative studies, equally there have been few direct comparisons between different classes of laxative and between different combinations of laxatives. There persists an uncertainty about the 'best' management of constipation in this group of patients.

A preclinical comparison between different opioids: antinociceptive versus adverse effects

Reduced side-effect liability of opioids may enhance the patient's quality of life and decrease the incidence of opioid-insensitive pain. Literature offers few comparative data between different opioids at equianalgesic doses. Therefore morphine, fentanyl, buprenorphine, codeine, hydrocodone and oxycodone were compared for analgesic properties and side-effect profiles in rats. Analgesic efficacy was analysed using a tail withdrawal test for acute thermal nociception, a formalin test for chemically induced inflammatory pain and a von Frey test for mechanical hypersensitivity. For side-effect profiling inhibition of gastrointestinal activity was evaluated in a charcoal and ricinus oil test, arterial PCO(2) was determined for measuring respiratory depression, the discriminative stimulus properties linked to the narcotic cue were assessed using a drug discrimination learning test, and motor coordination was tested through rotarod performance. ED(50)'s for the occurrence of side-effects were compared to ED(50)'s in behavioural pain tests. Fentanyl had a strong analgesic potency and, compared to other opioids, an acceptable side-effect profiling at analgesic ED(50)'s. Also consistent was the ceiling effect of buprenorphine implying an increased safety margin for side-effects, but a decreased analgesic efficacy. Differences between opioids as observed in this study can have important indications for their use in acute as well as in the onset of chronic treatments.

Comparative efficacy and safety of long-acting oral opioids for chronic non-cancer pain: a systematic review

Opioids have been endorsed as appropriate treatment for refractory chronic non-cancer pain when used according to published guidelines. They are widely used for this indication. However, there appear to be gaps in our understanding of the efficacy and safety of individual long-acting opioids compared to each other or as a class compared to short-acting opioids. This systematic review summarizes and assesses the evidence for the comparative efficacy and safety of long-acting opioids in the management of chronic non-cancer pain. Randomized trials (for comparative efficacy and adverse events) and observational studies (for adverse events only) that included non-parenteral long-acting opioids were sought using electronic databases, handsearching reference lists, and soliciting pharmaceutical company submissions. Searches were performed through October 2002. The validity of each included study was assessed using a data abstraction form and predefined criteria. An overall grade was allocated for the body of evidence for each key question. A total of 16 randomized trials (comparative efficacy and adverse events), enrolling 1427 patients, and 8 observational studies (adverse events) of 1190 patients were included in this review. No randomized trial was rated good quality; observational studies were generally of poorer quality than the trials. There was insufficient evidence to prove that different long-acting opioids are associated with different efficacy or safety profiles. There was also insufficient evidence to determine whether long-acting opioids as a class are more effective or safer than short-acting opioids. A subgroup of three studies on long-acting versus short-acting oxycodone was more homogeneous and provided fair evidence that these formulations are equally effective for pain control.