Side effects of morphine administration in cancer patients

Cancer management from a chronic gastrointestinal function perspective

Bowel dysfunction in cancer is a significant and challenging issue for both clinicians and patients. As cancer survival improves, the impact of gastrointestinal symptoms on quality of life is of ever-increasing relevance. This review aims to provide an overview of the common gastrointestinal complaints seen in cancer sufferers and discuss the principles of management and up to date treatment options available.

Ultramicronized N-Palmitoylethanolamine Regulates Mast Cell-Astrocyte Crosstalk: A New Potential Mechanism Underlying the Inhibition of Morphine Tolerance

Persistent pain can be managed with opioids, but their use is limited by the onset of tolerance. Ultramicronized N-palmitoylethanolamine (PEA) in vivo delays morphine tolerance with mechanisms that are still unclear. Since glial cells are involved in opioid tolerance and mast cells (MCs) are pivotal targets of PEA, we hypothesized that a potential mechanism by which PEA delays opioid tolerance might depend on the control of the crosstalk between these cells. Morphine treatment (30 μM, 30 min) significantly increased MC degranulation of RBL-2H3 cells, which was prevented by pre-treatment with PEA (100 μM, 18 h), as evaluated by β-hexosaminidase assay and histamine quantification. The impact of RBL-2H3 secretome on glial cells was studied. Six-hour incubation of astrocytes with control RBL-2H3-conditioned medium, and even more so co-incubation with morphine, enhanced CCL2, IL-1β, IL-6, Serpina3n, EAAT2 and GFAP mRNA levels. The response was significantly prevented by the secretome from PEA pre-treated RBL-2H3, except for GFAP, which was further upregulated, suggesting a selective modulation of glial signaling. In conclusion, ultramicronized PEA down-modulated both morphine-induced MC degranulation and the expression of inflammatory and pain-related genes from astrocytes challenged with RBL-2H3 medium, suggesting that PEA may delay morphine tolerance, regulating MC-astrocyte crosstalk.

Opioids, Double Effect, and the Prospects of Hastening Death

The relevance of double effect for end-of-life decision-making has been challenged recently by a number of scholars. The principal reason is that opioids such as morphine do not usually hasten death when administered to relieve pain at the end of life; therefore, no secondary "double" effect is brought about. In my article, I argue against this view, showing how the doctrine of double effect is relevant to the administration of opioids at the end of life. I contend that the prevailing view suffers from a misunderstanding of the nature of double effect, which includes application to risking a grave harm.

Morphine-Induced Constipation Develops With Increased Aquaporin-3 Expression in the Colon via Increased Serotonin Secretion

Aquaporin-3 (AQP3) is a water channel that is predominantly expressed in the colon, where it plays a critical role in the regulation of fecal water content. This study investigated the role of AQP3 in the colon in morphine-induced constipation. AQP3 expression levels in the colon were analyzed after oral morphine administration to rats. The degree of constipation was analyzed after the combined administration of HgCl(2) (AQP3 inhibitor) or fluoxetine (5-HT reuptake transporter [SERT] inhibitor) and morphine. The mechanism by which morphine increased AQP3 expression was examined in HT-29 cells. AQP3 expression levels in rat colon were increased during morphine-induced constipation. The combination of HgCl(2) and morphine improved morphine-induced constipation. Treatment with morphine in HT-29 cells did not change AQP3 expression. However, 5-HT treatment significantly increased the AQP3 expression level and the nuclear translocation of peroxisome proliferator-activated receptor gamma (PPARγ) 1 h after treatment. Pretreatment with fluoxetine significantly suppressed these increases. Fluoxetine pretreatment suppressed the development of morphine-induced constipation and the associated increase in AQP3 expression in the colon. The results suggest that morphine increases the AQP3 expression level in the colon, which promotes water absorption from the luminal side to the vascular side and causes constipation. This study also showed that morphine-induced 5-HT secreted from the colon was taken into cells by SERT and activated PPARγ, which subsequently increased AQP3 expression levels.

Design, synthesis, anticonvulsant and analgesic studies of new pyrazole analogues: a Knoevenagel reaction approach

Compounds1a,4aand7a(76.58, 79.76 and 78 94% protection) shows potent anticonvulsant activity compounds1b,5a,5b,7aand7bshowed good analgesic property.

Impact of prescribed medications on patient safety in older people

Appropriate prescribing for older adults presents unique challenges to the prescriber. An understanding of the scale of the problems and contributing factors is essential when designing interventions to improve patient safety. The altered pharmacology of ageing, the existence of multiple medical conditions and the exclusion of elderly patients from many trials render this subgroup of the population particularly vulnerable to underprescribing and overprescribing. Adverse drug events are common, causing significant morbidity and mortality as well as having economic implications. 'High-risk' medications such as opioids, anticoagulants and antipsychotics can have benefits in this group of patients but strategies to optimize their safety are required. Tools exist that help to identify those at risk of adverse drug reactions and to screen for inappropriate prescribing. Developments in information technology are ongoing, and it is hoped that these may enhance the process of medication reconciliation across healthcare transitions and alert the prescriber to potential adverse drug events. This review addresses commonly encountered issues when prescribing for older people, considers strategies to improve medication safety and offers a list of 'top tips' to aid the clinician.

Characterization of opioid activities of endomorphin analogs with C-terminal amide to hydrazide conversion

Previously, we have synthesized an endomorphin-2 (EM-2) analog with C-terminal amide to hydrazide conversion, exhibiting slightly lower μ-affinity than EM-2. In the present study, the influence of C-terminal amide group to hydrazide conversion on the in vitro and in vivo opioid activities of EMs was evaluated. Our results demonstrated that C-terminal amide to hydrazide conversion of EMs did not markedly change their μ-opioid receptor binding affinities. Nevertheless, EM-2-NHNH2 decreased guinea pig ileum (GPI) and mouse vas deferens (MVD) potencies by about 10- and 5-fold compared to the parent compound, respectively. It is noteworthy that EM-1-NHNH2 exhibited the highest antinociception after intracerebroventricular (i.c.v.) injection, about 1.5-fold more potent than EM-1, but with moderate colonic contractile and expulsive effects, comparable with EM-1. Additionally, though EM-2-NHNH2 showed a slightly lower antinociceptive effect than EM-2, at higher doses (i.c.v., 1.5 and 5 nmol/mouse) the inhibitory effects of colonic propulsion were significantly attenuated, which would be helpful in the development of suitable μ-opioid therapeutics, but without some undesirable side effects. Therefore, the present results gave the evidence that C-terminal amide to hydrazide conversion of EMs may play an important role in the regulation of opioid activities.

A Prospective, Randomized Trial of Intrathecal Injection vs. Epidural Infusion in the Selection of Patients for Continuous Intrathecal Opioid Therapy

The objective of this study was to compare the cost and safety of intrathecal injection (IN) vs. epidural infusion (CE) trial and to provide a preliminary assessment of the prognostic value of each in the selection of patients for long-term continuous intrathecal opioid therapy (CIOT). Thirty-seven patients with chronic nonmalignant pain who were being considered for CIOT were randomized to morphine trial by IN or CE. Analgesic response and complications were monitored throughout trial. Sixty-seven percent of IN (12/18) and 79% (15/19) of CE subjects reported good pain relief (defined as ≥ 50% pain reduction) and were implanted with a permanent infusion system. Eighty-nine percent (24/27) of subjects provided six-month CIOT follow-up data. Cost of trial and health care utilization during six months of CIOT were compared between groups. Analgesic and functional response during CIOT was also compared between IN and CE groups. The cost of IN trial was significantly less than CE trial (p < 0.001). Complications were generally mild in both groups, although opioid-related side effects tended to be more common in the IN group. Successful pain relief after six months of CIOT was reported by 10 (60%) and 14 (64%) patients who underwent IN and CE trial, respectively (p = 0.32; Fisher's exact test). There was no difference between IN and CE groups in McGill Pain rating, quality of life (VAS), mood (Profile of Mood States), or function (Sickness Impact Profile) after six months of CIOT. We conclude that intrathecal injection is a safe procedure for use in selection of patients for CIOT and is less costly than epidural infusion. Differences in pain and functional response to long-term opioids among patients selected by either trial method are not large.

Opioid-prescribing Practices in Chronic Cancer Pain in a Tertiary Care Pain Clinic

Introduction:

Under treatment of pain is a recognized global issue. Opioid analgesic medication is the mainstay of treatment in cancer patients as per the World Health Organization (WHO) pain relief ladder, yet 50% of cancer patients worldwide do not receive adequate pain relief or are undertreated.

Aim:

The aim of this study was to audit the ongoing opioid-prescribing practices in our tertiary cancer pain clinic during January–June 2010.

Materials & Methods:

The prescribed type of opioid, dose, dosing interval, and laxatives details were analyzed.

Results:

Five hundred pain files were reviewed and 435 were found complete for audit. Three hundred forty-eight (80%) patients were prescribed opioids. Two hundred fifty-nine (74.4%) received weak opioids while 118 (33.9%) received strong opioids. A total of 195 (45%) patients had moderate and 184 (42%) had severe pain. Ninety-three (26.7%) patients received morphine; however, only 31.5% (58 of 184) in severe pain received morphine as per the WHO pain ladder. Only 73 of 93 (78.4%) patients received an adequate dose of morphine with an adequate dosing interval and only 27 (29%) were prescribed laxatives with morphine.

Conclusion:

This study shows that the under treatment of pain and under dosing of opioids coupled with improper side effect management are major issues.

Synthesis and pharmacological evaluation of carbamic acid 1-phenyl-3-(4-phenyl-piperazine-1-yl)-propyl ester derivatives as new analgesic agents

A series of carbamic acid 1-phenyl-3-(4-phenyl-piperazine-1-yl)-propyl ester derivatives were synthesized through discovery strategies for balancing target-based in vitro screening and phenotypic in vivo screening. All the newly synthesized compounds were screened for their analgesic activities and compared with standard drug morphine. Among them, compound 44r, a potent analgesic agent that has favorable pharmacokinetic properties in rats and most importantly, has a wide safety margin. We demonstrated with in vitro and in vivo functional assays that its analgesic activity might be through 5-HT(2A) antagonism to some extent. Hence, it is concluded that there is ample scope for further study in developing compound 44r as a good lead candidate for an analgesic agent.

Subcutaneous methylnaltrexone for treatment of opioid-induced constipation in patients with chronic, nonmalignant pain: a randomized controlled study

Methylnaltrexone is effective for opioid-induced constipation (OIC) in advanced illness patients. This 4-week, double-blind, randomized, placebo-controlled study investigated the effect of subcutaneous methylnaltrexone on OIC in patients receiving opioids for chronic, nonmalignant pain. Patients (N = 460) received subcutaneous methylnaltrexone 12 mg once daily (QD) or every other day (alternating with placebo) compared with placebo. Assessments included bowel movement count, time of bowel movement, straining, sense of complete evacuation, Bristol Stool Form Scales, and quality of life. Within 4 hours of first dose, 34.2% of patients in both methylnaltrexone groups had rescue-free bowel movements (RFBMs) versus 9.9% on placebo (P < .001). The estimated number needed to treat was about 4. On average, 28.9% of methylnaltrexone QD and 30.2% of methylnaltrexone alternate-day dosing resulted in RFBMs within 4 hours versus 9.4% QD and 9.3% alternate-day placebo injections (both P < .001). Both methylnaltrexone groups had significantly shorter time to first RFBM (P < .001) and greater increase in number of weekly RFBMs (P < .05) versus placebo. Adverse events included abdominal pain, diarrhea, nausea, and hyperhidrosis. Bristol Stool Form Scale scores (P = .002) and sensation of complete evacuation (P < .04) were significantly superior with methylnaltrexone QD; both methylnaltrexone groups reported no or mild straining during RFBMs in the first 2 weeks (P < .02). At 4 weeks, a significantly greater improvement in patient-reported, constipation-specific quality of life was seen in the alternate-day dosing (P < .05) and QD (P < .001) groups.

PERSPECTIVE

We present data demonstrating that subcutaneous methylnaltrexone 12 mg given once daily (QD) or every other day provides significant relief of OIC and was generally well tolerated in patients with chronic, nonmalignant pain. These results expand on prior effectiveness observed for the treatment of OIC in advanced illness patients to a broader population.

Methylnaltrexone in the treatment of opioid-induced constipation in cancer patients receiving palliative care: willingness-to-pay and cost-benefit analysis

CONTEXT

When laxative regimens have failed, methylnaltrexone may be indicated for the relief of opioid-induced constipation (OIC) in patients with advanced illness receiving palliative care.

OBJECTIVES

A cost-benefit analysis (CBA), based on a willingness-to-pay (WTP) approach, was performed to determine if methylnaltrexone should be added to the formulary list of drugs being reimbursed by third-party payers in Canada for the treatment of cancer patients in palliative care suffering from OIC.

METHODS

The WTP study had two components: a decision board explaining treatment options (Component A) and a questionnaire to measure individual WTP using a bidding game approach (Component B). Component A had two options: Option 1 (laxatives only) and Option 2 (laxatives+methylnaltrexone injection). Only participants choosing Option 2 were invited to complete Component B. The results of the WTP survey were then incorporated into a CBA. Within a hypothetical cohort, additional monthly premiums that individuals were willing to pay for methylnaltrexone were compared with the monthly costs to the insurer for providing methylnaltrexone to all patients who would potentially be using it.

RESULTS

Four hundred one Canadians, of age 18 years and older, were surveyed and yielded a WTP in additional monthly insurance premiums of Canadian dollar (CAD) $8.65 (95% confidence interval: CAD$6.17-CAD$11.13). The CBA resulted in additional CAD$89,307 with a cost of CAD$139,840 and benefits of CAD$229,147. A set of 10,000 Monte Carlo simulations resulted in average CBA savings of CAD$145,011 with a 99.86% probability of dominance.

CONCLUSION

The present CBA provides pharmacoeconomic evidence for the adoption of methylnaltrexone for treating OIC in terminally ill cancer patients.

Biomarkers of opiate use

The interpretation of toxicological findings is critical for the thorough investigation of the use and abuse of psychoactive substances. A positive analytical result for a sample taken could usually result in criminal proceedings and a punitive outcome for the defendant whose sample was analysed. The detection of markers of illicit opiate misuse is important both in the management of substance misuse and in the postmortem identification of illicit opiate use. The aim of this study was to emphasise the role of opiate biomarkers available at the laboratory and in the clinical environment. Urine remains the biological tool of choice for qualitative detection of illicit drug use in a clinical setting, while quantitative accuracy remains strictly the domain of blood. Accurate interpretation of the screening tests within a clinical setting alongside other relevant information remains the key to the usefulness of any test. Moreover, the finding of a morphine/codeine concentration ratio in blood exceeding unity is a strong evidence that the person had used heroin, as opposed to having taken a prescription analgesic drug containing codeine.

Novel endomorphin analogues with antagonist activity at the mu-opioid receptor in the gastrointestinal tract

Opioid bowel dysfunction (OBD) summarizes common adverse side effects of opiate-based management of pain. A promising therapeutic approach to prevent OBD and other opioid-related disorders of the gastrointestinal (GI) tract is the co-administration of opiates with peripherally-restricted mu-opioid receptor (MOR)-selective antagonists. The aim of this study was to investigate the selectivity and efficacy of three novel peptide antagonists: antanal-1, antanal-2, and antanal-2A at MOR in the GI tract in vitro and in vivo. The effects of the antanals on GI motility were studied in vitro, using isolated preparations of mouse ileum and colon and in vivo, by measuring colonic propulsion in mice. Additionally, in vitro stability against enzymatic degradation and blood-brain barrier (BBB) permeability using the hot plate test in mice were examined. The antanals significantly reduced the inhibitory effect of the MOR agonists endomorphin-2, morphine, and loperamide on mouse ileum and colon contractions in vitro and blocked morphine-induced decrease of colonic bead expulsion in vivo. The hot plate test in mice showed that the antagonist activity of all antanals was restricted to the periphery. Antanal-1, antanal-2, and antanal-2A are promising MOR antagonists with limited BBB permeability, which may be developed into future therapeutics of opioid-related GI dysfunction.

Design, synthesis, and characterization of 6beta-naltrexol analogs, and their selectivity for in vitro opioid receptor subtypes

Since the mu opioid receptor (MOR) is known to be involved in the therapeutically relevant pathways leading to the manifestation of pain and addiction, we are currently studying the specific structural characteristics that promote antagonism at the MOR. The opiates 6beta-naltrexol and 6beta-naltrexamide function as neutral antagonists in in vitro and in vivo systems previously exposed to morphine, and are under investigation as improved treatments for narcotic dependence. In this research, we synthesized and characterized carbamate and sulfonate ester derivates of 6beta-naltrexol that do not contain a protic group at C(6), and evaluated these compounds for opioid receptor affinity. In vitro receptor subtype (mu, kappa, and delta opioid receptors) binding data of the carbamate and sulfonate derivatives is reported. All four compounds synthesized exhibited affinity for the MOR better than the standard 6beta-naltrexol HCl. Based on K(i) data, the order of MOR affinity is as follows: 9>13>14>10>6beta-naltrexol HCl. Carbamate 9 and tosylate 13 displayed subnanomolar affinity for the MOR, while 10 was the most mu-selective compound synthesized. In conclusion, our data indicate that the absence of a hydrogen-bond donor on the C(6) oxygen enhances rather than impedes the in vitro affinity of naltrexol derivatives for the MOR. Additionally, data also suggest that increasing the bulk around C(6) may allow control of subtype selectivity within these compound series.

Development of peripheral opioid antagonists' new insights into opioid effects

The recent approval by the US Food and Drug Administration of 2 medications--methylnaltrexone and alvimopan--introduces a new class of therapeutic entities to clinicians. These peripherally acting mu-opioid receptor antagonists selectively reverse opioid actions mediated by receptors outside the central nervous system, while preserving centrally mediated analgesia. Methylnaltrexone, administered subcutaneously, has been approved in the United States, Europe, and Canada. In the United States, it is indicated for the treatment of opioid-induced constipation in patients with advanced illness (eg, cancer, AIDS) who are receiving palliative care, when response to laxative therapy has not been sufficient. Alvimopan, an orally administered medication, has been approved in the United States to facilitate recovery of gastrointestinal function after bowel resection and primary anastomosis. Clinical and laboratory studies performed during the development of these drugs have indicated that peripheral receptors mediate other opioid effects, including decreased gastric emptying, nausea and vomiting, pruritus, and urinary retention. Laboratory investigations with these compounds suggest that opioids affect fundamental cellular processes through mechanisms that were previously unknown. These mechanisms include modifications of human immunodeficiency virus penetration, tumor angiogenesis, vascular permeability, and bacterial virulence.

Constipation in cancer patients on morphine

GOALS OF WORK

Constipation is a significant problem in patients taking morphine for cancer pain. The aims of this study were (1) to assess the magnitude of constipation in this study cohort, (2) to analyse the constipation treatment strategies and (3) to look for evidence of inter-individual variation in both susceptibility to constipation and response to treatment with laxatives in this patient group.

MATERIALS AND METHODS

This was an observational study carried out in a tertiary referral cancer hospital. Two hundred seventy four patients were recruited to the study. All had a diagnosis of cancer and were on oral morphine for cancer pain. The main outcomes measured were subjective patient assessment of constipation severity in the preceding week and laxative use. Patients were asked to grade constipation in the preceding week on a four-point categorical scale: "not at all" (grade 0), "a little" (grade 1), "quite a bit" (grade 2) and "very much" (grade 3). Laxative dose groups (LDGs) were developed to assess laxative dosing.

RESULTS

Constipation affects 72% of this cohort of patients. Constipation in this population is poorly managed. Eighty nine percent of constipated patients were on inadequate laxative therapy. Inter-individual variation in constipation on morphine exists: some patients do not experience constipation and do not need to take any laxatives, some patients do not experience constipation because they are taking laxatives and some patients experience constipation despite being on high dose laxatives. These three groups were compared in terms of cancer diagnosis, time on morphine, dose of morphine and other concomitant factors. No factor was identified to account for this inter-individual variation. Improvement in the clinical management of constipation is needed, with titration of laxatives according to individual patient need.

CONCLUSION

Constipation affects a large proportion of cancer patients taking oral morphine. Constipation in these patients is generally inadequately treated.

Going beyond efficacy: strategies for cancer pain management

Despite great advances in the fields of pain management and palliative care, pain directly or indirectly associated with a cancer diagnosis remains significantly undertreated. The present paper reviews the current standard for cancer pain management and highlights new treatments and targeted interventional techniques.

A review of methylnaltrexone, a peripheral opioid receptor antagonist, and its role in opioid-induced constipation

OBJECTIVES

Opioid medications are frequently used in pain and palliative care patients with malignancy to manage symptoms such as pain and dyspnea. However, opiates are associated with various side effects. Constipation is a particularly problematic and common side effect of opioid pharmacology. Opioid antagonists have been studied in the management of opioid-induced constipation. Methylnaltrexone (MNTX) is a peripheral opioid antagonist currently under clinical investigation. It offers the potential to reverse undesirable side effects without reversing analgesia.

METHODS

This article attempts to review existing clinical data, focusing on antagonism of opioid-induced adverse effects on the gastrointestinal system.

RESULTS

MNTX seems to be well tolerated with limited or transient side effects. MNTX has been shown to improve oral-cecal transit times in opioid treated patients, induce laxation in chronic opioid users, and neither reverses the analgesic effects of morphine nor cause withdrawal symptoms.

SIGNIFICANCE OF RESULTS

Larger clinical trials of MNTX are still necessary to support its use as a standard for treatment of opioid-induced constipation.

The in vitro pharmacology of the peripherally restricted opioid receptor antagonists, alvimopan, ADL 08-0011 and methylnaltrexone

This study characterized the pharmacology of the peripherally restricted opioid receptor antagonists, alvimopan, its metabolite, ADL 08-0011, and methylnaltrexone. The activities of the compounds were investigated with respect to human or guinea pig opioid receptor binding and function in recombinant cell lines and mechanical responsiveness of the guinea pig ileum. Alvimopan and ADL 08-0011 had higher binding affinity than methylnaltrexone at human mu opioid receptors (pK (i) values of 9.6, 9.6, and 8.0, respectively). The compounds had different selectivities for the mu receptor over human delta and guinea pig kappa opioid receptors. ADL 08-0011 had the highest mu receptor selectivity. With respect to their mu opioid receptor functional activity ([(35)S]GTPgammaS incorporation), methylnaltrexone had a positive intrinsic activity, consistent with partial agonism, unlike alvimopan and ADL 08-0011, which had negative intrinsic activities. Alvimopan, ADL 08-0011, and methylnaltrexone antagonized inhibitory responses mediated by the mu opioid agonist, endomorphin-1 (pA (2) values of 9.6, 9.4, and 7.6, respectively) and by U69593, a kappa opioid agonist (pA (2) values of 8.4, 7.2, and 6.7, respectively). In morphine-naive guinea pig ileum, methylnaltrexone reduced, while alvimopan and ADL 08-0011 increased, the amplitude of electrically evoked contractions and spontaneous mechanical activity. In tissue from morphine-dependent animals, alvimopan and ADL 08-0011 increased spontaneous activity to a greater degree than methylnaltrexone. The data suggested that alvimopan-induced contractions resulted predominantly from an interaction with kappa opioid receptors. It is concluded that alvimopan, ADL 08-0011, and methylnaltrexone differ in their in vitro pharmacological properties, particularly with respect to opioid receptor subtype selectivity and intrinsic activity. The clinical significance of the data from this study remains to be determined.

Effect of naloxone-3-glucuronide and N-methylnaloxone on the motility of the isolated rat colon after morphine

The effect of the opioid antagonists naloxone-3-glucuronide and N-methylnaloxone on rat colon motility after morphine stimulation was measured. The rat model consisted of the isolated, vascularly perfused colon. The antagonists (10(-4) M, intraluminally) and morphine (10(-4) M, intra-arterially) were administered from 20 to 30 and from 10 to 50 min, respectively. Colon motility was determined by the luminal outflow. The antagonist concentrations in the luminal and venous outflow were measured by high-performance liquid chromatography. Naloxone-3-glucuronide and N-methylnaloxone reversed the morphine-induced reduction of the luminal outflow to baseline within 10 and 20 min, respectively. These antagonists were then excreted in the luminal outflow and could not be found in the venous samples. Naloxone, produced by hydrolysis or demethylation, was not detectable. In conclusion, highly polar naloxone derivatives peripherally antagonize the motility-lowering effect of morphine in the perfused isolated rat colon, are stable, and are not able to cross the colon-mucosal blood barrier.

Peripherally Acting Mu-Opioid-Receptor Antagonists and the Connection Between Postoperative Ileus and Pain Management: The Anesthesiologist’s View and Beyond

The adverse effects of opioids are well documented. Because opioid receptors have a wide-ranging anatomic distribution, the effects subsequent to opioid binding, both good and bad, occur centrally and in the periphery. Postoperative strategies to reduce opioid burden, therefore, are in the patient's best interest. Multimodal analgesia is the key towards balancing the need for opioids while simultaneously reducing their burden. Alternative anesthesia and analgesia options such as regional anesthesia, nonsteroidal anti-inflammatory drugs, or cyclooxygenase-2 enzyme inhibitors should be considered part of multimodal protocols. Familiarity of where these drugs are active in the body and how they can be employed is imperative for all surgical team members. Optimal implementation of multimodal approaches can reduce hospital stay and improve clinical outcomes, including patient satisfaction. Finally, strategies that may help reduce rates of hospital readmission also contribute to overall improved outcome. New peripherally acting mu-opioid-receptor antagonists represent significant progress in the ability of perianesthesia nurses to play an even greater role in achieving these goals. In contrast to older opioid-receptor antagonists, these agents specifically target an important aspect of the multifactorial etiology of postoperative ileus (POI), mu-opioid-receptor-mediated activity in the GI tract. In addition, they do not pass the blood-brain barrier or diminish opioid-mediated analgesia. Advanced clinical trials have already demonstrated the ability of one of these agents, alvimopan, to reduce POI and improve other postoperative outcomes while maintaining adequate analgesia. Combined with other options aimed at reducing opioid burden, alvimopan and similar drugs in development hold promise as part of multimodal protocols to optimize pain management while minimizing postoperative morbidities.

Management of opioid-induced sedation in patients with cancer

Opioid-induced sedation is a common dose-limiting side effect of opioid therapy that can be very distressing and sometimes is more difficult to manage than pain. Opioid-induced sedation may prohibit patients from participating in certain activities of daily living, which can be a source of considerable distress for patients and their families. The issue presents a therapeutic dilemma for healthcare professionals caring for patients experiencing the side effect. Currently, several therapeutic approaches are used to counteract or minimize the severity of opioid-induced sedation, including reduction of the opioid dose, the addition of other drugs, opioid rotation, and the use of invasive routes of administration. This article will address the management of opioid-induced sedation.

Alvimopan

Alvimopan is a synthetic peripherally restricted mu-receptor opioid antagonist. Alvimopan has a greater affinity for the mu-receptor than the kappa- or sigma-opioid receptors (Ki = 0.77 nM). The polarity of the molecule limits gastrointestinal absorption and central nervous system penetration. It has limited systemic bioavailability and higher affinity for the mu-opioid receptor than naloxone (Ki = 3.7 nM). Completed Phase III trials suggest efficacy in accelerating the recovery of gastrointestinal function after abdominal surgery. Adverse events with all doses have been similar to placebo groups. Further efficacy in alleviating opioid-induced bowel dysfunction in patients with chronic opioid usage has also been demonstrated. This evidence-based review assesses this new drug and discusses its potential role in clinical practice.

Management of opioid-induced bowel dysfunction in cancer patients

The gastrointestinal (GI) effects of morphine and other opioids may result in opioid-induced bowel dysfunction (OBD) and the need for treatment. Although OBD is very common in morphine-treated patients, it is usually under-diagnosed. Opioids deliver their GI effect through central and peripheral mechanisms. Laxatives are the pharmaceuticals prescribed most in this area. Prokinetics as well as cholinergic agonists have been used satisfactorily. One-third of patients with OBD have to be treated rectally. The use of opioid antagonists has been favored, but the bioavailability of oral forms is poor. Opioid antagonists with a quaternary structure have a high affinity for peripheral opioid receptors and therefore do not interfere with the analgesia, nor do they generate alkaloid withdrawal syndrome. Opioid rotation is another strategy for maintaining or improving analgesic quality directed toward decreasing the effects of previous opiates on the GI tract.

Underutilisation of Opioids in Elderly Patients with Chronic Pain

The impact of poorly managed chronic pain on the quality of life of elderly patients and the problems related to its management are widely acknowledged. Underutilisation of opioids is a major component of poor pain management in this group of patients, despite good evidence for the effectiveness of opioids and published guidelines directing their usage. Reasons for this underutilisation are, among others, poor assessment of pain in this age group; fear of polypharmacy and opiophobia; and avoidance of opioids because of concerns about tolerance, physical dependence, addiction and adverse effects. This review suggests approaches to overcome these barriers to opioid usage, such as regular pain assessments, education to overcome opiophobia, rational prescribing, utilisation of less conventional opioids and non-oral routes of administration, avoidance of inappropriate opioids, opioid rotation, and education about managing or preventing adverse effects, the reasons why opioid therapy may be unsuccessful, and the effects of psychological factors on the pain experience. This more rational and knowledge-based approach to the use of opioids in the management of chronic pain in the elderly population should correct the current problems with underprescribing in this age group.

Tolerability of opioids in patients with acute pain due to nonmalignant musculoskeletal disease. A hospital-based observational study

OBJECTIVE

To evaluate the prevalence of adverse effects of opioids used to treat acute nonmalignant musculoskeletal pain.

METHODS

Prospective, single-center, observational study in patients admitted to a rheumatology department for a nonmalignant painful musculoskeletal condition with onset within the last 3 months and a need for WHO Class III analgesics. The following side effects were recorded daily: nausea and vomiting, constipation, pruritus, urinary retention, drowsiness, confusion, and hallucinations.

RESULTS

The 75 study patients (46 women and 29 men with a mean age of 56.4 years) were admitted for nerve root pain, osteoporotic vertebral fracture, inflammatory joint disease, or other disorders. First-line treatment was sustained-release morphine sulfate in a mean starting dosage of 55.2 mg/day. The dosage was increased if needed (mean maximum dosage, 78.3 mg/day). Mean treatment duration was 8.9 days. Adverse effects were recorded in 73.3% of patients but were usually minor, requiring no change in the treatment regimen. Eight patients experienced serious adverse effects (confusion in five and urinary retention in three) that resolved with no change in treatment in two patients, after dosage reduction in two patients and after substitution of fentanyl or hydromorphone hydrochloride in four patients. Treatment discontinuation was not associated with adverse effects.

CONCLUSIONS

Morphine is often responsible for adverse effects in patients with acute nonmalignant musculoskeletal pain. These effects are usually moderate and very rarely require discontinuation of the drug.

Alterations of Cajal cell in colon of slow transit constipation mice

AIM: To establish an animal model of slow transit constipation and to investigate the relationship between interstitial cell of Cajal in colon and the pathophysiological changes in the model of slow transit constipation.

METHODS: The mouse model was established by subcutaneous injection of morphine. According to period of morphine injected, the mice were divided into two groups: 2.5 mg/kg/per day ×30 d (n = 15) and 2.5 mg/kg/per day ×45 d (n = 15), and corresponding control groups were established by injecting the same dosage of 9 g/L sodium chloride solution. Fecal weight was recorded daily, and transit function of intestine was measured by activated charcoal suspension pushing test. The changes of interstitial cell of Cajal were observed by immunohistochemistry.

RESULTS: Fecal weight daily in test groupⅠwas less than control groupⅠ(18.8±3.2 g vs 20.6±1.8 g, P <0.05), and test groupⅡwas less than control group Ⅱ (16.8±2.0 g vs 22.0±3.2 g, P <0.01). It showed the significance of difference between the test groupⅠvs test groupⅡ(P <0.05), and no difference between two control groups (P >0.05). Intestinal transit rate in test group Ⅰwas lower than control groupⅠ(45.3±1.5% vs 49.2±1.8%, P <0.05), and test group Ⅱwas lower than control groupⅡ(40.6±1.3% vs 50.6±3.0%, P <0.01). There was a significant difference between test groupⅠvs test groupⅡ(P <0.05), and no difference between two control groups (P >0.05). Colon tissue c-kit+ cell's area in test groupⅠwas more decreased than that of control groupⅠ(81.3±7.9 ten thousand mm²vs 98.6±8.0 ten thousand mm², P <0.01), and test group Ⅱvs control groupⅡwas 66.5±8.4 vs 100.9±10.0 ten thousand mm² (P <0.01). There was a significant difference between the testⅠand testⅡ(P <0.01),and no difference in two control groups (P >0.05).

CONCLUSION: Daily fecal mass, intestinal transit ratio and the number of interstitial cells of Cajal are decreased in the mouse model of slow intestinal transit movement induced by morphine and have a positive correlation with period of morphine injected.

Interventions to overcome clinician- and patient-related barriers to pain management

Barriers to optimal cancer pain management exist among clinicians and patients, and within the healthcare system. This article focuses on clinician- and patient-related barriers and the interventions that have been tested to overcome them. Although individual studies have shown promise in improving patient outcomes, overall the studies do not provide clear answers to guide practice. Further research is required to determine what components of educational interventions are necessary to facilitate optimal cancer pain management.

Opioid-induced bowel dysfunction: pathophysiology and potential new therapies

Opioid treatment for postoperative or chronic pain is frequently associated with adverse effects, the most common being dose-limiting and debilitating bowel dysfunction. Postoperative ileus, although attributable to surgical procedures, is often exacerbated by opioid use during and following surgery. Postoperative ileus is marked by increased inhibitory neural input, heightened inflammatory responses, decreased propulsive movements and increased fluid absorption in the gastrointestinal tract. The use of opioids for chronic pain is characterised by a constellation of symptoms including hard dry stools, straining, incomplete evacuation, bloating, abdominal distension and increased gastroesophageal reflux. The current management of opioid-induced bowel dysfunction among patients receiving opioid analgesics consists primarily of nonspecific ameliorative measures. Intensive investigations into the mode of action of opioids have characterised three opioid receptor classes -mu, delta and kappa- that mediate the myriad of peripheral and central actions of opioids. Activation of mu-opioid receptors in the gastrointestinal tract is responsible for inhibition of gut motility, whereas receptors in the central nervous system mediate the analgesic actions of opioids. Blocking peripheral opioid receptors in the gut is therefore a logical therapeutic target for managing opioid-induced bowel dysfunction. Available opioid antagonists such as naloxone are of limited use because they are readily absorbed, cross the blood-brain barrier, and act at central opioid receptors to reverse analgesia and elicit opioid withdrawal. Methylnaltrexone and alvimopan are recently developed opioid antagonists with activity that is restricted to peripheral receptors. Both have recently shown the ability to reverse opioid-induced bowel dysfunction without reversing analgesia or precipitating central nervous system withdrawal signs in non-surgical patients receiving opioids for chronic pain. In addition, recent clinical studies with alvimopan suggest that it may normalise bowel function without blocking opioid analgesia in abdominal laparotomy patients with opioid-related postoperative ileus.

Pain management problems in patients' terminal phase as assessed by nurses in Finland

BACKGROUND

This study is part of a larger questionnaire survey concerned with the views of nursing staff on physical, emotional and spiritual support for terminally ill patients and decision making on the transition to the terminal phase of treatment.

AIM

This article discusses the results concerning the prevalence of physical pain in patients and with problems in pain management.

METHODS

A total of 328 nurses working on the inpatient wards of 32 municipal health centres in finland took part. Data were collected with multiple-choice items and one open-ended question, which were part of a larger structured questionnaire. The data were analysed by means of the SPSS statistical software and content analysis.

FINDINGS

Dying patients often suffered from pain, which was most commonly because of cancer. Intractable pain was common. The problems of pain management concerned attitudes and qualifications related to treating pain, the assessment of the pain, pain management per se and the organization of pain management.

CONCLUSION

The study highlights the need to increase pain education, discussion and agreement on the principles of pain management in municipal health centres in Finland.

Postoperative pain management: morphine versus ketorolac

Without proper management, postoperative pain can grow to intolerable levels and interfere with functioning and healing. Historically, morphine had no equal for postoperative pain management. Its side effects, however, are troubling. Recently, researchers have developed many analgesics that do not induce the same side effects as morphine. Ketorolac is one example. Nevertheless, a single drug with an efficacy comparable with morphine remains elusive. In this article, the physiology of pain is reviewed and ketorolac is compared with morphine. Perianesthesia nurses are given pertinent information to enhance their ability to provide the best pain relief available for the patients in their care.

A review of the potential role of methylnaltrexone in opioid bowel dysfunction

Opioids are widely used analgesics in patients with advanced cancer. However, their effectiveness for pain relief is often limited by the most frequently occurring side effect, opioid bowel dysfunction (OBD). Because conventional laxation measures are often ineffective in treating OBD, alternative approaches need to be investigated. Opioid action on the gut appears to be mediated mainly by receptors in the gastrointestinal (GI) tract rather than by those in the central nervous system (CNS). Opioid antagonists, such as naloxone, naltrexone, and nalmefene, have been studied as a means of antagonizing the peripheral effects of opioids, but these agents can enter the CNS and reverse analgesia or cause opioid withdrawal symptoms. Methylnaltrexone (MNTX) is a novel quaternary derivative of naltrexone that does not cross the blood-brain barrier and acts as a selective peripheral opioid receptor antagonist. In normal volunteers, intravenous or oral MNTX reverses opioid-induced reduction in bowel motility without affecting analgesia. Bioavailability of MNTX is low after oral administration, and plasma levels do not correlate with its actions in the gut, suggesting a predominantly local luminal action of MNTX on the gut. In patients receiving long-term opioid therapy, MNTX administered intravenously or orally was effective in reducing the delay in oral-cecal transit and eliciting laxation responses in all subjects without causing withdrawal symptoms. MNTX is a peripherally selective opioid antagonist that may have clinical utility in managing OBD with minimal adverse effects.

Relating palliative care principles to the promotion of undisturbed sleep in a hospice setting

Nurses working at night have a specific role in supporting sleep and promoting rest and comfort. Sometimes the role of the night duty nurse in promoting sleep and comfort is taken for granted. One author's experience of working as a night duty nurse led to reflection on her responsibilities in improving practice and addressing the sleep-related needs of patients in a palliative care setting. Following a literature review, it was clear that there are very few publications on sleep disturbance in palliative care. Using the four principles of palliative care (Aranda, 1998a), the authors construct a series of strategies to prevent and manage sleep issues.

Novel 3-(4-piperidinylthio)-1H-indoles as potent nonopioid orally active central analgesics

A series of 3-(4-piperidinylthio)-1H-indoles was synthesized and evaluated in mice in the phenylbenzoquinone(PBQ)-induced writhing and hot plate tests. Most of these compounds are good analgesics with activities comparable to that of morphine. Among them compound 1i (UP 237-61), which has a strong serotonin binding profile, has an interesting antinociceptive activity which is not reversed by naloxone.

Intrathecal grafting of unencapsulated adrenal medullary tissue can bring CD4 T lymphocytes into CSF: a potentially deleterious event for the graft

Adrenal medullary tissue including chromaffin cells was grafted intrathecally in cancer patients to relieve intractable pain. The central nervous system (CNS) is considered an immune privileged site. Therefore, non-HLA-matched and unencapsulated tissue was grafted in 15 patients and 1 sham control in a series of at least 20 grafts. We observed an increase in CSF lymphocyte counts in 15/20 allografts (75%). In contrast to peripheral blood, CD4 T cells predominated in the CSF, but failed to exhibit an activated phenotype (CD25+ CD45RO+ HLA-DR+). The positive effect of graft on pain, the high met-enkephalin levels, the absence of any increase in CSF cytokine levels particularly for IFN-gamma or IL-2 (but not IL-10 and IL-6), indirectly indicated that the graft was tolerated despite the presence of CSF lymphocytes. The single treatment failure and three of four cases of partial efficacy occurred in grafts where CSF lymphocytes were present. Moreover, when assayed (n = 7), the CD4+ CSF lymphocytes still retained the capacity to exhibit ex vivo a normal or enhanced frequency of T CD4 cells producing IFN-gamma and IL-2. Taken together, our observations indicate that impairment of the local immunosuppressive balance can lead to activation of those CSF CD4 T cells and drive a rejection process. This study suggests further work on the purification and/or the immunoisolation of tissues grafted in the CNS will be necessary, particularly when the possibility of long-term and repeated grafting is considered.