Alvimopan addition to a standard perioperative recovery pathway

Effect of Alvimopan on Postoperative Ileus and Length of Hospital Stay in Patients Undergoing Bowel Resection: A Systematic Review and Meta-Analysis

AIMS

The aim is to investigate the effect of alvimopan on postoperative ileus and length of hospital stay in patients undergoing bowel resection.

METHODS

The PRISMA statement standards were followed to conduct a systematic review and meta-analysis. The available literature was searched to identify all studies comparing alvimopan with no alvimopan in patients undergoing bowel resection. Postoperative ileus and length of hospital stay were the primary outcomes, and time to first bowel motion was the secondary outcome. Random-effects modeling was applied for analyses.

RESULTS

Analysis of 94 833 patients from 26 studies showed that alvimopan was associated with lower risk of postoperative ileus (OR: .57, 95% CI .48 to .67, P <.00001; high GRADE certainty), shorter length of hospital stay (MD: -1.08 day, 95% CI -1.36 to -.81, P < .00001; moderate GRADE certainty), and shorter time to first bowel motion (MD: -.43 day, 95% CI -.58 to -.28, P < .00001; moderate GRADE certainty). Separate analyses of randomized controlled trials and observational studies showed similar findings. Subgroup analyses suggested consistent findings in patients undergoing elective bowel resection, emergency bowel resection, and open surgery; however, alvimopan did not improve the outcomes in patients undergoing minimally invasive surgery.

CONCLUSION

Robust evidence supports the routine use of alvimopan in patients undergoing open bowel resection as indicated by lower risk of postoperative ileus and shorter length of hospital stay. We support incorporation of alvimopan into enhanced recovery after surgery programs for the procedures involving open bowel resection. The role of alvimopan in minimally invasive bowel resection needs more research.

Postoperative Ileus after Minimally Invasive Colorectal Surgery: A Summary of Current Strategies for Prevention and Management

BACKGROUND

Postoperative ileus (POI) is one of the most common postoperative complications after colorectal surgery and prolongs hospital stays. Minimally invasive surgery (MIS) has reduced POI, but it remains common. This review explores the current methods for preventing and managing POI after MIS.

SUMMARY

Preoperative interventions, including optimising nutrition, preoperative medicationn, and mechanical bowel preparation with oral antibiotics, may have a role in preventing POI. Transversus abdominis plane blocks and lidocaine could replace epidural analgesia in MIS. Fluid overload should be avoided; in some cases, goal-directed fluid therapy may aid in achieving this. Pharmacological agents, such as prucalopride and dexmedetomidine, could target mechanisms underlying POI. New strategies to stimulate vagal nerve activity may promote postoperative gastrointestinal motility. Preoperative bowel stimulation could potentially reduce POI following loop ileostomy closure. However, the evidence base for several interventions remains weak and requires further corroboration with robust studies.

KEY MESSAGES

Despite the increasing use of MIS, POI remains a major issue following colorectal surgery. Further strategies to prevent POI are rapidly emerging. Studies using standardised definitions and perioperative care will help validate these interventions and remove barriers to accurate meta-analysis. Future studies should focus on establishing the impact of these interventions on POI after MIS specifically.

Selective Opioid Antagonists Following Bowel Resection for Prevention of Postoperative Ileus: a Systematic Review and Meta-analysis

BACKGROUND

Postoperative ileus (POI) remains a common complication following bowel resection. Selective opioid antagonists have been increasingly studied as prophylactic pharmaceutical aids to reduce rates of POI. The aim of this study was to evaluate the impact of selective opioid antagonists on return of bowel function following bowel resection.

METHODS

MEDLINE, Embase, and CENTRAL were systematically searched. Articles were included if they compared the incidence of POI and/or length of stay (LOS) in patients receiving and not receiving selective opioid antagonists following elective bowel resection. A pairwise meta-analyses using inverse variance random effects was performed.

RESULTS

From 636 citations, 30 studies with 45,051 patients receiving selective opioid antagonists (51.3% female, mean age: 60.9) and 55,071 patients not receiving selective opioid antagonists (51.2% female, mean age: 61.1) were included. Patients receiving selective opioid antagonists had a significantly lower rate of POI (10.1% vs. 13.8%, RR 0.68, 95%CI 0.63-0.75, p < 0.01). Selective opioid antagonists also significantly reduced LOS (MD - 1.08, 95%CI - 1.47 to - 0.69, p < 0.01), readmission (RR 0.94, 95%CI 0.89-0.99, p = 0.03), and 30-day morbidity (RR 0.85, 95%CI 0.79-0.90, p < 0.01). Improvements in LOS, readmission rate, and morbidity were not significant when analysis was limited to laparoscopic surgery. There was no significant difference in inpatient healthcare costs (SMD - 0.33, 95%CI - 0.71-0.04, p = 0.08).

CONCLUSIONS

Rate of POI decreases with the use of selective opioid antagonists in patients undergoing bowel resection. Selective opioid antagonists also improve LOS, rates of readmission, and 30-day morbidity for patients undergoing open bowel resection. Addition of these medications to enhance recovery after surgery protocols should be considered.

Comparison of treatment to improve gastrointestinal functions after colorectal surgery within enhanced recovery programmes: a systematic review and meta-analysis

Despite a significant improvement with enhanced recovery programmes (ERP), gastro-intestinal (GI) functions that are impaired after colorectal resection and postoperative ileus (POI) remain a significant issue. In the literature, there is little evidence of the distinction between the treatment assessed within or outside ERP. The purpose was to evaluate the efficiency of treatments to reduce POI and improve GI function recovery within ERP. A search was performed in PubMed and Scopus on 20 September 2019. The studies were included if they compared the effect of the administration of a treatment aiming to treat or prevent POI or improve the early functional outcomes of colorectal surgery within an ERP. The main outcome measures were the occurrence of postoperative ileus, time to first flatus and time to first bowel movement. Treatments that were assessed at least three times were included in a meta-analysis. Among the analysed studies, 28 met the eligibility criteria. Six of them focused on chewing-gum and were only randomized controlled trials (RCT) and 8 of them focused on Alvimopan but none of them were RCT. The other measures were assessed in less than 3 studies over RCTs (n = 11) or retrospective studies (n = 2). In the meta-analysis, chewing gum had no significant effect on the endpoints and Alvimopan allowed a significant reduction of the occurrence of POI. Chewing-gum was not effective on GI function recovery in ERP but Alvimopan and the other measures were not sufficiently studies to draw conclusion. Randomised controlled trials are needed.Systematic review registration number CRD42020167339.

The association of alvimopan treatment with postoperative outcomes after abdominal surgery: A systematic review across different surgical procedures and contexts of perioperative care

BACKGROUND

Alvimopan is a Food and Drug Administration-approved treatment to accelerate gastrointestinal recovery after abdominal surgery; however, benefits may vary across different procedures and contexts of care. The purpose of this study is to summarize the evidence regarding the effect of alvimopan on postoperative outcomes after abdominal surgery.

METHODS

Major databases (Medline, Embase, Biosis, Cochrane, Web of Science, and Scopus) were searched for randomized controlled trials and nonrandomized studies comparing alvimopan versus control. Risk of bias was assessed using Cochrane's risk of bias tool 2.0 (for randomized controlled trials) and Risk of Bias in Nonrandomized Studies-of Intervention tool (for nonrandomized studies). Results were appraised descriptively as heterogeneity in reporting and risk of bias hindered meta-analysis. Quality of evidence across different surgical procedures and contexts of care (ie, open versus minimally invasive surgery, traditional care versus enhanced recovery pathway) was evaluated using Grading of Recommendations Assessment, Development, and Evaluation.

RESULTS

Nine randomized controlled trials and 35 nonrandomized studies were identified. Evidence of low to moderate certainty supports that alvimopan reduces length of stay and improves gastrointestinal recovery after open bowel resection and open radical cystectomy. Limited evidence supports alvimopan for surgeries not listed in Food and Drug Administration labels (ie, total abdominal hysterectomy and retroperitoneal lymph node dissection). Similar effects were observed in traditional and enhanced recovery pathway settings, but enhanced recovery pathway elements varied across studies. There is very low certainty of evidence supporting alvimopan for patients undergoing minimally invasive surgery.

CONCLUSION

Evidence supports that alvimopan improves outcomes after open bowel resection and open radical cystectomy. Benefits for patients undergoing minimally invasive surgery and treated in contemporary enhanced recovery pathway settings remain uncertain. These findings contribute important new knowledge to inform evidence-based alvimopan prescribing.

Alvimopan Significantly Reduces Length of Stay and Costs Following Colorectal Resection and Ostomy Reversal Even Within an Enhanced Recovery Protocol

BACKGROUND

Alvimopan accelerates GI recovery after colorectal resection. Data on real-world cost-effectiveness have been mixed.

OBJECTIVE

This study aimed to evaluate if adding alvimopan to an enhanced recovery pathway reduces length of stay.

DESIGN

Patients undergoing colorectal resection or ostomy reversal for the year before and after the introduction of alvimopan were evaluated.

SETTING

This study was conducted at a single academic medical center.

PATIENTS

Patients undergoing elective colorectal resection (488) or ostomy reversal (148) were included.

MAIN OUTCOME MEASURES

The primary outcomes measured were length of stay and prolonged length of stay defined as >75th percentile for each procedure.

RESULTS

Two hundred eighty-six patients (45%) received alvimopan. Alvimopan and no-alvimopan groups had similar demographics, comorbidities, operative indication, and case mix. In the alvimopan group, more of the colorectal resections were laparoscopic (87% vs 79%, p = 0.015). Length of stay was reduced with alvimopan (6.2 vs 4.9 days, p = 0.003), and this effect persisted when controlling for procedure type, approach, and ASA class (decreased length of stay by 1.0 day, p = 0.014). The alvimopan group had lower risk of prolonged length of stay (14.7% vs 23.1%, p = 0.007) and ileus (10.8% vs 16.2%, p = 0.05). On multivariable analysis, no alvimopan use (OR, 1.8; 95% CI, 1.2-2.7), ASA ≥3 (OR, 2.0; 95% CI, 1.3-3.1), and history of cardiac surgery (OR, 2.8; 95% CI, 1.2-6.5) were significant predictors of prolonged length of stay. Alvimopan use was associated with a lower risk of infectious complications other than surgical site infection (2.8% vs 6.7%, p = 0.025), and did not increase risk of any adverse outcomes. The addition of alvimopan to the protocol resulted in cost savings of $708.39 per patient.

LIMITATIONS

Data collected from a single center limit external validity.

CONCLUSIONS

The introduction of alvimopan to a postoperative protocol following elective colorectal resection or ostomy reversal significantly reduces length of stay and is associated with cost savings even within an enhanced recovery protocol. See Video Abstract at http://links.lww.com/DCR/A911.

Evaluation of Healthcare Use and Clinical Outcomes of Alvimopan in Patients Undergoing Bowel Resection: A Propensity Score-Matched Analysis

BACKGROUND

Postoperative ileus is a significant complication after bowel resection surgeries. Alvimopan is the only US Food and Drug Administration-approved therapy for accelerating the return of bowel function after large- and small-bowel resection.

OBJECTIVE

The purpose of this study was to estimate the healthcare use and in-hospital morbidities associated with on-label use of alvimopan in patients undergoing bowel resection surgeries.

DESIGN

A retrospective observational propensity-matched cohort study was conducted using a large hospital administrative database.

SETTING

The study included inpatient postsurgical patients.

PATIENTS

Patients aged ≥18 years undergoing a primary large or small segmental bowel resection with discharge dates between January 2010 and December 2014 were included.

INTERVENTIONS

Patients receiving 2 to 15 doses of alvimopan were defined as the treatment cohort, and those without any alvimopan use were included as control subjects.

MAIN OUTCOME MEASURES

The primary outcome was postoperative length of stay. Secondary outcomes included postoperative in-hospital morbidities, inpatient mortality, intensive care unit length of stay, discharge disposition, and 30-day readmission.

RESULTS

Each propensity-score matched cohort included 18,559 patients. The mean (±SD) postoperative length of stay was 4.62 ± 2.45 days in alvimopan-treated patients compared with 5.24 ± 3.35 days in control subjects (p < 0.001). Alvimopan-treated patients had lower rates of postoperative GI complication (12.15% vs 16.50%; p < 0.001). The rates of urinary tract infections; other postoperative infections; and cardiovascular, pulmonary, thromboembolic, and cerebrovascular events were also lower compared with the control subjects.

LIMITATIONS

The study was limited by its inability to generalize to the US population, because the database included a convenience sample of hospital discharges. The identification of patients undergoing bowel resection and their clinical conditions relied on the accuracy and completeness of International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis and procedure coding. There may be a confounding effect by the use of enhanced recovery pathways associated with the use of alvimopan.

CONCLUSIONS

The use of alvimopan was associated with a reduction of 0.62 days in postsurgery length of stay and lower rates of postoperative GI complications, infections, and other in-hospital morbidities. See Video Abstract at http://links.lww.com/DCR/A703.

Alvimopan Provides Additional Improvement in Outcomes and Cost Savings in Enhanced Recovery Colorectal Surgery

OBJECTIVE

To examine the impact of alvimopan on outcomes and costs in a rigorous enhanced recovery colorectal surgery protocol.

BACKGROUND

Postoperative ileus remains a major source of morbidity and costs in colorectal surgery. Alvimopan has been shown to reduce incidence of postoperative ileus in enhanced recovery colorectal surgery; however, data are equivocal regarding its benefit in reducing length of stay and costs.

METHODS

Patients undergoing major elective enhanced recovery colorectal surgery were identified from a prospectively-collected database (2010-2013). Multivariable analyses were employed to compare outcomes and hospital costs among patients who had alvimopan versus no alvimopan by adjusting for demographic, clinical, and treatment characteristics.

RESULTS

A total of 660 patients were included; 197 patients received alvimopan and 463 patients had no alvimopan. In unadjusted analysis, the alvimopan group had a faster return of bowel function, shorter length of stay, and lower rates of ileus, Foley re-insertion, and urinary tract infection (all P < 0.01). After adjustment, alvimopan was associated with a faster return of bowel function by 0.6 day (P = 0.0006), and lower incidence of postoperative ileus (odds ratio 0.23, P = 0.0002). With adjustment, alvimopan was associated with a shorter length of stay by 1.6 days (P = 0.002), and a hospital cost savings of $1492 per patient (P = 0.01).

CONCLUSIONS

Alvimopan administration as an element of enhanced recovery colorectal surgery is associated with faster return of bowel function, lower incidence of postoperative ileus, shorter hospitalization, and a significant cost savings. These results suggest that alvimopan is cost-effective in the setting of enhanced recovery colorectal surgery protocols, and should therefore be considered in these programs.

Randomized clinical trial of chewing gum after laparoscopic colorectal resection

BACKGROUND

Chewing gum may enhance intestinal motility after surgery. This trial studied whether chewing gum could lead to a further reduction in ileus in patients who had a laparoscopic colorectal resection and followed an enhanced recovery programme.

METHODS

Patients undergoing laparoscopic colorectal resection were randomized to a control or intervention group. Patients in the control group received a standardized recovery programme. Patients in the intervention group were, in addition, given chewing gum three times daily from day 1 until discharge. Primary outcome measures were time to first flatus and first bowel motion. Time to feeling hungry and hospital stay were secondary outcome measures.

RESULTS

Forty-one patients were randomized into each group. Thirty-seven patients underwent rectal resection and 45 had a colonic resection. Time to passage of flatus was shorter (18 versus 34 h; P = 0·007), first bowel motion occurred earlier (19 versus 44 h; P = 0·001) and time to feeling hungry was earlier (16 versus 25 h; P = 0·001) in the intervention group. There was no difference in the duration of hospital stay (5 days in the intervention group versus 5·5 days in the control group). Subgroup analyses revealed that the benefits of chewing gum were clearer in patients who had a colonic resection, with a shorter time to first flatus (20 versus 35 h; P = 0·043), first bowel motion (19 versus 53 h; P = 0·014) and feeling hungry (14 versus 40 h; P = 0·001). No adverse events were attributed to chewing gum.

CONCLUSION

Chewing gum is a simple intervention that speeds intestinal transit in patients managed with a recovery programme after laparoscopic colorectal resection.

REGISTRATION NUMBER

NCT02419586 (https://clinicaltrials.gov/).

The use of alvimopan for postoperative ileus in small and large bowel resections

Transient ileus is a normal physiologic process after surgery. When prolonged, it is an important contributor to postoperative complications, increased length of stay and increased healthcare costs. Efforts have been made to prevent and manage postoperative ileus; alvimopan is an oral, peripheral μ-opioid receptor antagonist, and the only currently US FDA-approved medication to accelerate the return of gastrointestinal function postoperatively.

Is there value in alvimopan in minimally invasive colorectal surgery?

BACKGROUND

Alvimopan's goal is to minimize postoperative ileus and optimize outcomes; however, evidence in laparoscopic surgery is lacking. Our goal was to evaluate the benefit of alvimopan in laparoscopic colorectal surgery with an enhanced recovery pathway (ERP).

METHODS

Laparoscopic colorectal cases were stratified into alvimopan and control cohorts, then case-matched for comparability. All followed an identical ERP. The main outcomes were length of stay, complications, readmissions, and costs in the alvimopan and control groups.

RESULTS

About 321 patients were analyzed in each cohort. Operative times were comparable (P = .08). Postoperatively, complication rates were similar (P = .29), with no difference in ileus (P = 1.00). The length of stay (3.69 vs 3.49 days; P = .16), readmission (2.8% vs 3.7%; P = .66) and reoperation rates (2.2% vs 1.6%; P = .77) were comparable for alvimopan and controls, respectively. Total costs were similar ($14,932.47 alvimopan vs $14,846.56 controls; P = .90), but the additional costs in the alvimopan group could translate to savings of $27,577 in the cohort.

CONCLUSIONS

Alvimopan added no benefit in patient outcomes in laparoscopic colorectal surgery with an ERP. These results could drive a change in current practice. Controlled studies are warranted to define the cost and/or benefit in clinical practice.

Alvimopan combined with enhanced recovery strategy for managing postoperative ileus after open abdominal surgery: a systematic review and meta-analysis

BACKGROUND

To assess the efficacy and safety of alvimopan in conjunction with enhanced recovery strategy, compared with this strategy alone, in management of postoperative ileus in patients undergoing open abdominal surgery.

METHODS

Electronic databases were comprehensively searched for relevant randomized controlled trials. We were interested in doses of 6 and 12 mg. The efficacy end points included the time to recovery of full gastrointestinal (GI) function (a composite end point measured by the time to first toleration of solid food [SF] and the time to first passage of stool, GI-2), the recovery of upper (SF) or the lower (the time to first bowel movement, BM) GI function, and the length of hospital stay (the time to discharge order written). Safety end points included GI-related, non-GI-related, and serious adverse events. These parameters were all analyzed by RevMan 5.3 software.

RESULTS

Nine randomized controlled trials involving 4075 patients were enrolled in this study. The pooled results showed that alvimopan significantly decreased the time to GI-2 recovery (6 mg, hazard ratio [HR] = 1.45, P < 0.00001; 12 mg, HR = 1.59, P < 0.00001), BM (6 mg, HR = 1.54, P < 0.00001; 12 mg, HR = 1.74, P = 0.0002), and the time to discharge order written (6 mg, HR = 1.37, P < 0.00001; 12 mg, HR = 1.34, P < 0.00001) compared with the placebo group. However, SF was significantly reduced in 6 mg group (HR = 1.23, P = 0.008) rather than 12 mg group (HR = 1.14, 95% confidence interval 1.00, 1.30, P = 0.04). The incidence of some GI-related and serious adverse events were significantly lower in the alvimopan group than the placebo group, and the dose of 12 mg was superior to 6 mg in this regard.

CONCLUSIONS

Alvimopan can accelerate recovery of GI function (especially for the lower GI tract), shorten the length of hospital stay, and reduce postoperative ileus-related morbidity without compromising opioid analgesia in an enhanced recovery setting.

Incidence of prolonged postoperative ileus after colorectal surgery: a systematic review and meta-analysis

AIM

Prolonged postoperative ileus (PPOI) after colorectal surgery remains a leading cause of delayed postoperative recovery and prolonged hospital stay. Its exact incidence is unknown. The aim of this systematic review is to investigate the definitions and incidence of PPOI previously described.

METHOD

MEDLINE, Embase and the Cochrane Database of Systematic Reviews (up to July 2014) were searched. Two authors independently reviewed citations using predefined inclusion and exclusion criteria.

RESULTS

The search strategy yielded 3233 citations; 54 were eligible, comprising 18 983 patients. Twenty-six studies were prospective [17 of these being randomized controlled trials (RCTs)] and 28 were retrospective. Meta-analysis revealed an incidence of PPOI of 10.3% (95% CI 8.4-12.5) and 10.2% (95% CI 5.6-17.8) for non-RCTs and RCTs, respectively. Significant heterogeneity was observed for both non-RCTs and for RCTs. The used definition of PPOI, the type of surgery and access (laparoscopic, open) and the duration of surgery lead to significant variability of reported PPOI incidence between studies. The incidence of PPOI is lower after laparoscopic colonic resection.

CONCLUSION

There is a large variation in the reported incidence of PPOI. A uniform definition of PPOI is needed to allow meaningful inter-study comparisons and to evaluate strategies to prevent PPOI.

Does alvimopan enhance return of bowel function in laparoscopic gastrointestinal surgery? A meta-analysis

BACKGROUND

Postoperative ileus (POI) remains a major impediment in patient recovery and leads to longer lengths of stay at the hospital, readmission rates, and hospital costs. Alvimopan, a mu-opioid receptor antagonist, lowers POI incidence following open gastrointestinal surgery, however, little is known about its role on POI prevention among patients undergoing laparoscopic gastrointestinal surgery.

METHODS

A comprehensive search of PubMed/MEDLINE, Scopus, CINAHL, and Cochrane databases was performed (December 2014). Meta-analysis was performed using the Mantel-Haenszel (fixed effects) model with odds ratio (OR) to assess prevention of POI and hospital readmission.

RESULTS

Five studies were included in the final analysis. Pooling 4 of 5 studies, there was over a 75% relative risk reduction in POI development when patients were given alvimopan compared to placebo (OR 0.24, 95%CI 0.12-0.51, P=0.02). The number needed to treat with alvimopan to prevent one POI episode was 11 patients. There was a modest reduction in the length of hospitalization between 0.2 and 1.6 days. There did not appear to be a difference in frequency of 30-day readmission rate among the alvimopan group compared to placebo (OR 1.15, 95%CI 0.54-2.45, P=0.62).

CONCLUSION

Overall, there was a 75% relative risk reduction in POI development among patients undergoing laparoscopic gastrointestinal surgery. However, there did not appear to be a significant reduction in all-cause 30-day readmission rate or length of hospitalization. Future studies will need to address which subset of patients undergoing laparoscopic gastrointestinal surgery will benefit most from alvimopan.

Facilitating return of bowel function after colorectal surgery: alvimopan and gum chewing

Postoperative ileus is common after colorectal surgery, and has a huge impact on hospital LOS. With the impeding cost crisis in the United States, safely reducing length of stay is essential. Chewing gum and pharmacological treatment with alvimopan are safe, simple tools to reduce postoperative ileus and its associated costs. Future research will determine if integrating these tools with laparoscopic procedures and enhanced recovery pathways is a best practice in colorectal surgery.

Physiology, signaling, and pharmacology of opioid receptors and their ligands in the gastrointestinal tract: current concepts and future perspectives

Opioid receptors are widely distributed in the human body and are crucially involved in numerous physiological processes. These include pain signaling in the central and the peripheral nervous system, reproduction, growth, respiration, and immunological response. Opioid receptors additionally play a major role in the gastrointestinal (GI) tract in physiological and pathophysiological conditions. This review discusses the physiology and pharmacology of the opioid system in the GI tract. We additionally focus on GI disorders and malfunctions, where pathophysiology involves the endogenous opioid system, such as opioid-induced bowel dysfunction, opioid-induced constipation or abdominal pain. Based on recent reports in the field of pharmacology and medicinal chemistry, we will also discuss the opportunities of targeting the opioid system, suggesting future treatment options for functional disorders and inflammatory states of the GI tract.

A critical appraisal of lubiprostone in the treatment of chronic constipation in the elderly

Chronic constipation is a common disorder in the general population, with higher prevalence in the elderly, and is associated with worse quality of life and with greater health care utilization. Lubiprostone is an intestinal type-2 chloride channel activator that increases intestinal fluid secretion, small intestinal transit, and stool passage. Lubiprostone is currently approved by the US Food and Drug Administration for the treatment of chronic idiopathic constipation and of irritable bowel syndrome with predominant constipation. This review outlines current approaches and limitations in the treatment of chronic constipation in the elderly and discusses the results, limitations, and applicability of randomized, controlled trials of lubiprostone that have been conducted in the general and elderly population, with additional focus on the use of lubiprostone in constipation in Parkinson's disease and in opioid-induced constipation, two clinical entities that can be comorbid in elderly patients.