Effects of naloxegol on whole gut transit in opioid-naïve healthy subjects receiving codeine: A randomized, controlled trial.

BACKGROUND: Nausea, vomiting, and constipation (OIC) are common adverse effects of acute or chronic opioid use. Naloxegol (25 mg) is an approved peripherally active mu-opiate opioid receptor antagonist. AIM: To compare the effects on pan-gut transit of treatment with codeine, naloxegol, or combination in healthy volunteers. METHODS: We conducted a randomized, double-blind, placebo-controlled, single-center, parallel-group study in 72 healthy opioid-naïve adults, randomized to: codeine (30 mg q.i.d.), naloxegol (25 mg daily), codeine and naloxegol, or matching placebo. During 3 days of treatment, we measured gastric emptying (GE) T1/2 , colonic filling at 6 hours (CF6), colonic geometric center at 24 and 48 hours, and ascending colon emptying (ACE) T1/2 . KEY RESULTS: Participants were 59.7% women, median BMI 25.0 kg/m2 , and median age 33.8 years. Codeine significantly retarded GE T1/2, CF6, overall colonic transit, and ACE T1/2 . There was significant difference (P = .026) in GE T1/2 between codeine (144.0 min [IQR 110.5-238.6]) and naloxegol (95.5 min [89.1-135.4]). There was a significant overall group difference in CF6 (P = .023), with significant difference (P = .019) between codeine (11.0% [0.0-45.0]) and naloxegol (51% [18.8-76.2]). However, no significant differences were found between codeine-treated participants concomitantly receiving placebo or naloxegol. CONCLUSIONS AND INFERENCES: Short-term administration of naloxegol (25 mg) in healthy, opioid-naïve volunteers does not reverse the retardation of gastric, small bowel, or colonic transit induced by acute administration of codeine. Further studies with naloxegol at higher dose are warranted to assess the ability to reverse the retardation of transit caused by acute administration of codeine in opioid-naïve subjects.

Effects of Antidepressants on Gastric Function in Patients with Functional Dyspepsia.

BACKGROUND: Functional dyspepsia (FD) is a highly prevalent functional bowel disorder. The effects of antidepressant therapy (ADTx) on gastric sensorimotor function in FD patients are poorly understood. AIMS: Determine whether FD and subtypes with abnormalities in gastric function respond differently to ADTx compared to those with normal physiology. METHODS: This multicenter, prospective trial randomized FD patients to 12 weeks of amitriptyline (AMI; 50 mg), escitalopram (ESC; 10 mg), or matching placebo. Demographics, symptoms, psychological distress, gastric emptying, and satiation were measured. Gastric accommodation (GA) using single-photon emission computed tomography imaging was performed in a subset of patients. An intent to treat analysis included all randomized subjects. The effect of treatment on gastric emptying was assessed using ANCOVA. A post hoc appraisal of the data was performed categorizing patients according to the Rome III subgrouping (PDS and EPS). RESULTS: In total, 292 subjects were randomized; mean age=44 yrs. 21% had delayed gastric emptying. Neither antidepressant altered gastric emptying, even in those with baseline delayed gastric emptying. GA increased with ADTx (P=0.02). Neither antidepressant affected the maximal-tolerated volume (MTV) of the nutrient drink test although aggregate symptom scores improved compared to placebo (P=0.04). Patients with the combined EPS-PDS subtype (48%) had a lower MTV on the nutrient drink test compared to the EPS group at baseline (P=0.02). Postprandial bloating improved with both AMI (P=0.03) and ESC (P=0.02). CONCLUSIONS: Amitriptyline (50 mg) improves FD symptoms but does not delay gastric emptying, even in patients with baseline delayed gastric emptying. GA improved with low-dose ADTx; the precise mechanism of action is unknown warranting further study.

Secretory diarrhea and hypokalemia associated with colonic pseudo-obstruction: A case study and systematic analysis of the literature.

BACKGROUND: Colonic pseudo-obstruction (CPO) is characterized by colonic distention in the absence of mechanical obstruction or toxic megacolon. Concomitant secretory diarrhea (SD) with hypokalemia (SD-CPO) due to gastrointestinal (GI) loss requires further characterization. AIM: To perform a systematic review of SD-CPO, report a case study, and compare SD-CPO with classical CPO (C-CPO). METHODS: We performed a search of MEDLINE, EMBASE, Cochrane, and Scopus for reports based on a priori criteria for CPO, SD and GI loss of potassium. An additional case at Mayo Clinic was included. RESULTS: Nine publications met inclusion criteria, with a total of 14 cases. Six studies had high, three moderate, and our case high methodological quality. Median age was 74 years (66-97), with 2:1 male/female ratio. Kidney disease was present in 6/14 patients. Diarrhea was described as profuse, watery, or viscous in 10 patients. Median serum, stool, and urine potassium concentrations (mmol/L) were 2.4 (range: 1.9-3.1), 137 (100-180), and 17 (8-40), respectively. Maximal diameter of colon and cecum (median) were 10.2 cm and 10.5 cm, respectively. Conservative therapy alone was effective in five out of 14 patients. Median potassium supplementation was 124 mEq/d (40-300). Colonic decompression was effective in three out of six patients; one had a total colectomy; three out of 14 had died. The main differences between SD-CPO and C-CPO were lower responses to treatments: conservative measures (35.7% vs 73.6%, P=.01), neostigmine (17% vs 89.2%, P<.001), and colonic decompression (50% vs 82.4%, P=.02). CONCLUSION: SD-CPO is a rare phenotype associated with increased fecal potassium and is more difficult to treat than C-CPO.

Effect of neostigmine on gastroduodenal motility in patients with suspected gastrointestinal motility disorders.

BACKGROUND: Acetylcholinesterase inhibitors (ACIs), e.g., neostigmine, are known to increase upper and lower gastrointestinal (GI) motility and are used to treat acute colonic pseudoobstruction. However, their effects on gastroduodenal motility in humans are poorly understood. Our hypotheses were that, in patients with suspected GI motility disorders, neostigmine increases gastric and small intestinal motor activity, and these effects are greater in patients with cardiovagal neuropathy, reflecting denervation sensitivity. METHODS: In this open label study, the effects of neostigmine (1 mg intravenously) on gastroduodenal motor activity recorded with manometry were assessed in 28 patients with a suspected GI motility disorder. Cardiovagal function was assessed with the heart rate response to deep breathing and GI transit by scintigraphy. KEY RESULTS: The final diagnoses were gastroparesis (6 patients), gastroparesis with intestinal neuropathy (3 patients), intestinal neuropathy or pseudoobstruction (5 patients), functional dyspepsia (6 patients), chronic abdominal pain (3 patients), mechanical small intestinal obstruction (3 patients), and pelvic floor dysfunction (2 patients). Neostigmine increased both antral and intestinal phasic pressure activity (p < 0.001). Neostigmine increased antral and intestinal pressure activity in 81% and 50% of patients with reduced postprandial antral and intestinal contractile responses to meal, respectively. The antroduodenal pressure response to neostigmine was not higher in patients with cardiovagal dysfunction. CONCLUSIONS & INFERENCES: Neostigmine increased antral and intestinal motor activity in patients with hypomotility, including intestinal dysmotility. These responses to neostigmine were not greater in patients with cardiovagal dysfunction. The use of longer-acting ACIs for treating antroduodenal dysmotility warrant further study.

A novel technique for bedside anorectal manometry in humans.

BACKGROUND: Currently, anorectal manometry (ARM), which is used to diagnose defecatory disorders and identify anal weakness in fecal incontinence (FI) is generally conducted in specialized laboratories. Our aims were to compare anorectal functions measured with high-resolution manometry (HRM) and a novel portable manometry device. METHODS: Anal pressures at rest, during squeeze, and simulated evacuation, and rectal sensation were evaluated with portable and HRM in 20 healthy women, 19 women with constipation, and 11 with FI. The relationship between anal pressures measured with portable and HRM was assessed by the concordance correlation coefficient (CCC), Bland Altman test, and paired t-tests. KEY RESULTS: Anal pressures at rest (CCC 0.45; 95% CI: 0.29, 0.58) and during squeeze (CCC 0.60; 95% CI: 0.46, 0.72) measured with portable and HRM were correlated and inversely associated with the risk of FI. During simulated evacuation, the CCC for rectal pressure (0.62; 95% CI: 0.43, 0.76) was greater than that for anal pressure (CCC 0.22; 95% CI: 0.04, 0.39) and the rectoanal gradient (CCC 0.22; 95% CI: 0.02, 0.41). Rectal sensory thresholds for first sensation, the desire to defecate, and urgency measured by portable and HRM were also significantly correlated between techniques. For several parameters, differences between portable and HRM were statistically significant and the Bland Altman test was positive. CONCLUSIONS & INFERENCES: Anorectal pressures and rectal sensation can be conveniently measured by portable manometry and are significantly correlated with high-resolution manometry.

Immunotherapy trial as diagnostic test in evaluating patients with presumed autoimmune gastrointestinal dysmotility.

BACKGROUND: Chronic gastrointestinal dysmotility greatly impacts the quality of life. Treatment options are limited and generally symptomatic. Neural autoimmunity is an under-recognized etiology. We evaluated immunotherapy as an aid to diagnosing autoimmune gastrointestinal dysmotility (AGID). METHODS: Twenty-three subjects evaluated at the Mayo Clinic for suspected AGID (August 2006-February 2014) fulfilled the following criteria: (1) prominent symptoms of gastrointestinal dysmotility with abnormalities on scintigraphy-manometry; (2) serological evidence or personal/family history of autoimmune disease; (3) treated by immunotherapy on a trial basis, 6-12 weeks (intravenous immune globulin, 16; or methylprednisolone, 5; or both, 2). Response was defined subjectively (symptomatic improvement) and objectively (gastrointestinal scintigraphy/manometry studies). KEY RESULTS: Symptoms at presentation: constipation, 18/23; nausea or vomiting, 18/23; weight loss, 17/23; bloating, 13/23; and early satiety, 4/23. Thirteen patients had personal/family history of autoimmunity. Sixteen had neural autoantibodies and 19 had extra-intestinal autonomic testing abnormalities. Cancer was detected in three patients. Preimmunotherapy scintigraphy revealed slowed transit (19/21 evaluated; gastric, 11; small bowel, 12; colonic, 11); manometry studies were abnormal in 7/8. Postimmunotherapy, 17 (74%) had improvement (both symptomatic and scintigraphic, five; symptomatic alone, eight; scintigraphic alone, four). Nine responders re-evaluated had scintigraphic evidence of improvement. The majority of responders who were re-evaluated had improvement in autonomic testing (six of seven) or manometry (two of two). CONCLUSIONS & INFERENCES: This proof of principle study illustrates the importance of considering an autoimmune basis for idiopathic gastrointestinal dysmotility and supports the utility of a diagnostic trial of immunotherapy.

Evaluating symptom outcomes in gastroparesis clinical trials: validity and responsiveness of the Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD).

BACKGROUND: Patient-reported symptom scales are needed to evaluate treatments for gastroparesis. The Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD) was developed to assess daily symptoms of gastroparesis. This study evaluated the validity and responsiveness of the GCSI-DD in patients with gastroparesis. METHODS: Symptomatic patients were started with a new treatment for gastroparesis. Patients completed the GCSI-DD each evening during a baseline week and for 8 weeks of treatment. Responders were defined based on patient and clinician global rating of change. Minimal important differences (MID) were estimated based on baseline to 4 week changes in symptoms scores for small improvements. KEY RESULTS: Of 69 patients participating, 46 had idiopathic, 19 diabetic, and four postfundoplication gastroparesis. Excellent test-retest reliability was seen for GCSI-DD scores, and there were significant correlations between GCSI-DD scores and clinician ratings of symptom severity. Responders to treatment reported improvements in nausea [effect size (ES) = 0.42, P < 0.001], postprandial fullness, ES = 0.83, P < 0.001), bloating (ES = 0.34, P < 0.001), early satiety (ES = 0.53, P < 0.001), but lower responses for upper abdominal pain (ES = 0.29), and vomiting (ES = 0.22; P = 0.119). MIDs were 0.55 for nausea, 0.97 for excessive fullness, 0.63 for bloating, 0.77 for postprandial fullness, and 0.30 for abdominal pain. A composite score of four symptoms (Composite-1; nausea, bloating, excessive fullness, postprandial fullness) had ES of 0.61 and MID of 0.73. Composite-2 score (nausea, early satiety, bloating, abdominal pain) had a lower ES of 0.47. CONCLUSIONS & INFERENCES: Symptoms of early satiety, nausea, postprandial fullness, and bloating were responsive to treatment for gastroparesis. A composite of these symptoms also demonstrates validity and responsiveness to treatment for gastroparesis, and may represent an acceptable endpoint for evaluating the effectiveness of medical treatments in clinical trials for gastroparesis.

Gastroparesis and functional dyspepsia: excerpts from the AGA/ANMS meeting.

BACKGROUND: Despite the relatively high prevalence of gastroparesis and functional dyspepsia, the aetiology and pathophysiology of these disorders remain incompletely understood. Similarly, the diagnostic and treatment options for these two disorders are relatively limited despite recent advances in our understanding of both disorders. PURPOSE: This manuscript reviews the advances in the understanding of the epidemiology, pathophysiology, diagnosis, and treatment of gastroparesis and functional dyspepsia as discussed at a recent conference sponsored by the American Gastroenterological Association (AGA) and the American Neurogastroenterology and Motility Society (ANMS). Particular focus is placed on discussing unmet needs and areas for future research.

Optimizing analysis of stable isotope breath tests to estimate gastric emptying of solids.

Breath tests (BT) using 13C-substrates have been proposed for the measurement of gastric emptying (GE). The mathematical analysis of the breath 13CO2 excretion that most accurately predicts GE t(1/2) from simultaneous scintigraphy is unresolved. To compare five mathematical methods to estimate GE t(1/2) by BT with t(1/2) from simultaneous scintigraphy. Data acquired from a dual-labelled solid-liquid meal containing 99mTc sulphur colloid and 13C-Spirulina platensis from 57 healthy volunteers were used to compare four mathematical methods reported in the literature [Ghoos method; generalized linear regression (Viramontes); linear regression (Szarka); Wagner-Nelson method] and the total cumulative breath 13CO2 excretion with > or =12 breath samples collected over at least 4 h. The concordance correlation coefficient (CCC) for the t(1/2) results obtained with each method using BT data was compared with the results obtained with scintigraphy. The linear regression and generalized linear regression methods used five samples at 45, 90, 120, 150 and 180 min. All methods, except for the Wagner-Nelson method, resulted in mean GE t(1/2) that approximated t(1/2) obtained with scintigraphy. The highest CCC was observed with the linear regression method. Simple cumulative excretion of breath 13CO2 provides a better CCC than the Ghoos method. The linear regression and generalized linear regression methods (which also require relatively few breath samples) provide the most accurate analyses of breath 13CO2 excretion in stable isotope GEBT.

Does co-administration of a non-selective opiate antagonist enhance acceleration of transit by a 5-HT4 agonist in constipation-predominant irritable bowel syndrome? A randomized controlled trial.

Opioid neurons exhibit tonic restraint on intestinal motility; opioid antagonists stimulate peristalsis and increase transit. In vitro, 5-hydroxytryptamine (5-HT4) agonists combined with selective opioid antagonists significantly increased colonic propulsion relative to a 5-HT4 agonist alone. We hypothesized that the combination of 5-HT4 agonist and non-selective opioid antagonist enhances intestinal transit more than either treatment alone in female constipation-predominant irritable bowel syndrome (C-IBS) patients. Our aim was to examine the effect of tegaserod 6 mg b.i.d. alone and combined with naltrexone 50 mg on intestinal transit and stool characteristics in females with C-IBS. Forty-eight patients were randomized to tegaserod alone, naltrexone alone or in combination with tegaserod or placebo for 6 days. Small bowel, ascending colon half-life (in pharmacokinetics) (t1/2), and colonic geometric centre (8, 24, 48 h) were assessed by scintigraphy. Tegaserod increased small bowel (P < 0.01) and colon transit (P < 0.01). Naltrexone did not accelerate colonic transit relative to placebo. Combination treatment did not significantly accelerate transit relative to tegaserod alone. Tegaserod and tegaserod with naltrexone resulted in looser stool form (P < 0.01). In female C-IBS patients, tegaserod accelerates small bowel and colon transit and contributed to looser stool consistency. Use of naltrexone, 50 mg, does not support the hypothesis that combination of 5-HT4 agonist and non-selective opioid antagonist enhances intestinal transit.

Effects of pramlintide, an amylin analogue, on gastric emptying in type 1 and 2 diabetes mellitus.

Pramlintide delays gastric emptying, possibly by a centrally mediated mechanism. Our aim was to determine whether the effects of pramlintide on gastric emptying differ in people with type 1 or type 2 diabetes who had no history of complications. Using a randomized, three-period, two-dose, crossover design, we studied the effects of 0, 30, or 60 microg t.i.d. pramlintide subcutaneously for 5 days each in six type 1 and six type 2 diabetic subjects. Gastric emptying of solids was measured by 13C-Spirulina breath test. Plasma pancreatic polypeptide (HPP) response to the test meal was also measured. Relative to placebo [t 50% 91 +/- 6 min (means +/- SEM)], pramlintide equally delayed gastric emptying following 30 or 60 microg t.i.d. (268 +/- 37 min, 329 +/- 49 min, respectively; P < 0.01]. Postprandial HPP levels were lower in response to 30 and 60 microg pramlintide compared to placebo. There were no significant differences in the effects on gastric emptying or HPP levels between type 1 and type 2 diabetic subjects. Pramlintide delays gastric emptying in diabetes unassociated with clinically detected complications. Further studies are needed in diabetic patients with impaired gastric motor function.

Effects of an alpha(2)-adrenergic agonist on gastrointestinal transit, colonic motility, and sensation in humans.

To characterize alpha(2)-adrenergic control of motor and sensory functions of gastrointestinal tract and colon, we studied dose-related effects of clonidine (placebo or up to 0.3 mg po) by random assignment in 55 healthy humans. Gastrointestinal transit was measured in all subjects; in 35, we assessed colonic compliance, tone, and sensations of gas and pain during phasic distensions. Clonidine did not significantly alter gastrointestinal or colonic transit, but it increased colonic compliance and reduced fasting tone without altering colonic response to a meal. Clonidine significantly reduced aggregate sensation to distensions overall and had significant linear dose-related sensory effects at 8- and 24-mmHg distensions. Effect on pain (including dose-response relationship) was due to 0.3-mg dose for distensions at 24 mmHg. We confirmed that clonidine relaxes fasting colonic tone and reduces sensation of pain. In this study, gut transit was not altered by clonidine, and novel dose-response characteristics and clonidine's effect on gas sensation are provided. Doses as low as 0.05 mg may be effective and potentially useful in reducing colonic tone and gas sensation.

Diagnosing gastroesophageal reflux disease.

Gastroesophageal reflux disease (GERD) is a common condition with a variety of clinical manifestations and potentially serious complications. This article reviews available methods for diagnosing GERD. A clinical history of the classic symptoms of GERD, heartburn or acid regurgitation, is sensitive enough to establish the diagnosis in patients without other complications. Esophagogastroduodenoscopy is the best way to evaluate suspected complications of GERD, but endoscopic findings are insensitive for the presence of pathological reflux, and therefore they cannot reliably exclude GERD. The "gold standard" study for confirming or excluding the presence of abnormal gastroesophageal reflux is the 24-hour ambulatory esophageal pH monitoring test, and this study should be used for the evaluation of refractory symptoms and extraesophageal manifestations of GERD. A formal acid-suppression test is helpful in the evaluation of the atypical GERD symptom of noncardiac chest pain. Optimal use of currently available tests for GERD may allow for more efficient diagnosis and better characterization of the pathological manifestations associated with GERD.

Recombinant human neurotrophic factors accelerate colonic transit and relieve constipation in humans.

BACKGROUND & AIMS: The aim of this study was to assess the effects of recombinant human brain-derived neurotrophic factor (r-metHuBDNF) and recombinant human neurotrophic factor 3 (r-metHuNT-3) on gastrointestinal motor functions in healthy people and in patients with constipation. METHODS: Gastrointestinal and colonic transit was measured by scintigraphy before and after 2 weeks of treatment. Daily diaries documented symptoms over 6 weeks before, during, and after treatment. In a randomized study of healthy subjects, 40 received 100 microg/kg r-metHuBDNF or placebo subcutaneously (SC) daily. In a separate study, 8 healthy subjects and 8 patients with constipation received 300 microg/kg r-metHuNT-3 SC thrice weekly. RESULTS: r-met-HuBDNF accelerated overall and proximal colonic emptying (P<0.05) in health. r-metHuNT-3 accelerated overall colonic transit in health and constipation (all P<0.05) and gastric and small bowel transit (both P<0.05) in health. r-metHuBDNF tended to increase stool frequency compared with placebo in health (P = 0.09). r-metHuNT-3 increased stool frequency (P = 0.05) and facilitated passage of stool (P < 0.01) in constipated patients. The effects on stool frequency started within 3 days of the beginning of neurotrophin administrations and lasted up to 5 days after treatment ended. r-metHu neurotrophic factors were well tolerated, although half of the participants in the 2 studies developed injection site reactions or paresthesiae. CONCLUSIONS: Exogenous neurotrophic factors stimulate human gut motility in health and constipation.

Pramlintide, an amylin analog, selectively delays gastric emptying: potential role of vagal inhibition.

The amylin analog pramlintide delays gastric emptying in type I diabetics. The effects of multiple doses of pramlintide and the mechanism of action in non-amylin-deficient humans are unknown. We investigated the effects of pramlintide on gastrointestinal and colonic transit and on the plasma pancreatic polypeptide response to the meal in a parallel-group dose-response study with subjects randomized to placebo, or 30 or 60 microg (tid, sc) of pramlintide. Pramlintide delayed gastric emptying [half-time (t(1/2)): 112 min (SE 8.7 min), 169 min (SE 12 min), or 177 min (SE 25 min) after placebo or 30- or 60-microg pramlintide treatment, respectively; P = 0.033]. Pramlintide did not significantly affect small bowel or colonic transit. Pancreatic polypeptide concentrations in the first postprandial hour were lower with pramlintide than with placebo (P<0.01 for drug effect). An inverse correlation was observed between mean pancreatic polypeptide concentrations in the first postprandial hour and gastric emptying t(1/2) [Spearman correlation coefficient (R(s)) = 0.48; P = 0.044]. Pramlintide at 30 and 60 microg delays gastric emptying in healthy humans without affecting small bowel or colonic transit. Vagal inhibition is a potential mechanism of the effects of pramlintide on gastric emptying.

Practical pointers for grappling with GERD. Heartburn gnaws at quality of life for many patients.

GERD is a common condition, generally caused by transient LES relaxations. The spectrum of disease due to GERD is wide, ranging from symptoms alone to esophagitis, Barrett's esophagus, and respiratory tract complications. Excellent diagnostic test are available to confirm the diagnosis and stage the disease, and medications can predictably relieve symptoms and heal even the most severe forms of esophagitis. Finally, surgical therapy is an effective option for patients with truly refractory disease or for those patients with significant disease who prefer not to use drug treatment.