Prokinetic effects of mirtazapine on gastrointestinal transit

Mirtazapine Therapy for a Patient With Weight Loss and Gastroparesis Associated With Limited Systemic Sclerosis

Objective: Gastroparesis may be present in individuals with systemic sclerosis. In the United States, metoclopramide is the only medication approved for treating gastroparesis. Our case involves using mirtazapine therapy to help with weight loss and gastroparesis associated with systemic sclerosis. Case: A 70-year-old female with limited systemic sclerosis and sicca syndrome began experiencing weight loss, dysphagia, nausea, and abdominal fullness. Neither an esophageal dilation procedure nor six weeks of metoclopramide therapy alleviated her symptoms. However, 15 mg of mirtazapine once daily provided some symptomatic relief. A gastric emptying scan confirmed gastroparesis. The dose of mirtazapine was later increased to 30 mg once daily. With the mirtazapine therapy, the patient experienced both symptomatic improvement and weight gain benefits. Discussion/Conclusion: Mirtazapine therapy has anti depressive, appetite stimulating, anti-emetic, and prokinetic benefits. Consideration of mirtazapine therapy for patients with weight loss and gastroparesis associated with systemic sclerosis may be beneficial.

The Intersection of Disorders of Gut-Brain Interaction With Avoidant/Restrictive Food Intake Disorder

High rates of overlap exist between disorders of gut-brain interaction (DGBI) and eating disorders, for which common interventions conceptually conflict. There is particularly increasing recognition of eating disorders not centered on shape/weight concerns, specifically avoidant/restrictive food intake disorder (ARFID) in gastroenterology treatment settings. The significant comorbidity between DGBI and ARFID highlights its importance, with 13% to 40% of DGBI patients meeting full criteria for or having clinically significant symptoms of ARFID. Notably, exclusion diets may put some patients at risk for developing ARFID and continued food avoidance may perpetuate preexisting ARFID symptoms. In this review, we introduce the provider and researcher to ARFID and describe the possible risk and maintenance pathways between ARFID and DGBI. As DGBI treatment recommendations may put some patients at risk for developing ARFID, we offer recommendations for practical treatment management including evidence-based diet treatments, treatment risk counseling, and routine diet monitoring. When implemented thoughtfully, DGBI and ARFID treatments can be complementary rather than conflicting.

Gastric Motility Disorders in Dogs and Cats

Gastric motility disorders present both diagnostic and therapeutic challenges and likely are under-recognized in small animal practice. This review includes a comparative overview of etiopathogenesis and clinical presentation of gastric motility disorders, suggests a practical approach to the diagnosis of these conditions, and provides an update on methods to evaluate gastric motor function. Furthermore, management of gastric dysmotility is discussed, including a review of the documented effect of gastric prokinetics.

The Management of Nausea and Vomiting Not Related to Anticancer Therapy in Patients with Cancer

OPINION STATEMENT

In cancer patients, the management of nausea and vomiting that is not directly related to treatment is challenging. Much current practice is based on expert opinion and anecdote. Fortunately, over recent years, a number of quality trials have been undertaken to strengthen the evidence base that guides the care of our patients with these distressing symptoms. Much is still unknown however. In this article, we present the latest literature that addresses some of the outstanding issues.

Electroacupuncture via chronically implanted electrodes improves gastrointestinal motility by balancing sympathovagal activities in a rat model of constipation

Electroacupuncture (EA) has been reported for treating constipation in clinical studies. However, little is known of the possible mechanisms involved in the prokinetic effect of EA. The aim of this study was to investigate the effects and underlying autonomic mechanisms of EA via chronically implanted electrodes for constipation in rat induced by Loperamide (Lop). Lop was given to regular rats to induce constipation. EA was performed via a pair of electrodes chronically implanted at bilateral acupoint ST-36. Feces characteristics, gastric emptying, small intestinal transit, distal colon transit time (dCTT), and whole gut transit time (WGTT) were measured in various sessions with EA or sham EA in rats with constipation induced by Lop. Heart rate variability (HRV) derived from the electrocardiogram was analyzed to evaluate autonomic functions. The number of fecal pellets was reduced by 27% with Lop (P < 0.01) and normalized by 7-day EA. Similar results were also observed in pellet weight. In normal rats compared with sham EA, EA shortened dCTT by 74% (P < 0.05 vs. sham EA), increased small intestinal transit by 28% (P < 0.01) and gastric emptying by 27% (P < 0.05), and accelerated whole gut transit by 14% (P < 0.05). In Lop-treated rats, the dCTT and WGTT were prolonged by Lop and normalized by EA. Lop significantly decreased vagal activity and increased sympathetic nerve activity; however, EA reversed these effects. EA at ST-36 via chronically implanted electrodes improves Lop-induced constipation by enhancing GI motility via the autonomic mechanisms. NEW & NOTEWORTHY The findings of the present study suggest that the proposed electroacupuncture (EA) may have great therapeutic potential for treating patients with opioid-induced constipation. It was demonstrated that EA at ST-36 improved transit of every organ along the gut mediated via the autonomic mechanisms in normal rats and rats with Lop-induced constipation. It is advised to administrate EA daily instead of two or three times weekly as reported in most of the clinical studies.

Gastrointestinal Tract Dysfunction With Critical Illness: Clinical Assessment and Management

The gut is the site of digestion and absorption as well as serving as an endocrine and immune organ. All of these functions may be affected by critical illness. This review will discuss secondary effects of critical illness on the gut in terms of gastrointestinal function that is clinically observable and discuss consequences of gut dysfunction with critical illness to patient outcome. Because there is little evidence-based medicine in the veterinary field, much of our understanding of gut dysfunction with critical illness comes from animal models or from the human medical field. We can extrapolate some of these conclusions and recommendations to companion animals, particularly in dogs, who have similar gastrointestinal physiology to people. Additionally, the evidence regarding gut dysfunction in veterinary patients will be explored. By recognizing signs of dysfunction early and taking preventative measures, we may be able to increase success with treatment of critical illnesses.

Clinical measurement of gastrointestinal motility and function: who, when and which test?

Symptoms related to abnormal gastrointestinal motility and function are common. Oropharyngeal and oesophageal dysphagia, heartburn, bloating, abdominal pain and alterations in bowel habits are among the most frequent reasons for seeking medical attention from internists or general practitioners and are also common reasons for referral to gastroenterologists and colorectal surgeons. However, the nonspecific nature of gastrointestinal symptoms, the absence of a definitive diagnosis on routine investigations (such as endoscopy, radiology or blood tests) and the lack of specific treatments make disease management challenging. Advances in technology have driven progress in the understanding of many of these conditions. This Review serves as an introduction to a series of Consensus Statements on the clinical measurements of gastrointestinal motility, function and sensitivity. A structured, evidence-based approach to the initial assessment and empirical treatment of patients presenting with gastrointestinal symptoms is discussed, followed by an outline of the contribution of modern physiological measurement on the management of patients in whom the cause of symptoms has not been identified with other tests. Discussions include the indications for and utility of high-resolution manometry, ambulatory pH-impedance monitoring, gastric emptying studies, breath tests and investigations of anorectal structure and function in day-to-day practice and clinical management.

Autonomic dysfunction of gastric motility in major depression

BACKGROUND

Patients suffering from major depressive disorder (MDD) often complain about somatic symptoms. Cardiac complaints have been examined predominantly. However, gastrointestinal complaints are also reported frequently and are associated with worse outcomes. The research concerning changes in gastric motility of these patients is rather sparse. The aim of our study was to determine dysfunction of gastric motility and gastrointestinal symptoms in MDD. The duration and severity of MDD were examined regarding its influence over gastric emptying.

METHODS

Gastric emptying was determined by a ¹³C-acetate breath test in patients with MDD (n = 29) and healthy control subjects (n = 51). Prior to this, depressive illness was operationalized using external and self-assessment scales (HAMD-21, MADRS, BDI, CGI). Whether the severity or duration of MDD influenced the gastric emptying parameters was examined using Spearman's correlation. In addition, autonomic complaints were recorded by means of an ANS score. Each ANS score item was determined using a Mann-Whitney U or Kruskal-Wallis test concerning the gastric emptying parameters.

RESULTS

There was a significant difference in the parameters of the maximum gastric emptying rate (T_max) and gastric half emptying time T_1/2b between patients with MDD and healthy control subjects (T_max 66.21min vs 53.35min, p < 0.006, T_1/2b 207.59min vs 133.27min, p < 0.005). There was a significant negative correlation between T_max and the severity of MDD determined with the depression rating scales BDI (Spearman's rank - 0.521, p = 0.013) and HAMD-21 (r - 0.384, p = 0.048). No correlation was found between the duration of MDD and the maximum gastric emptying rate (r - 0.125, p = 0.519) and gastric half emptying time (r - 0.62, p = 0.749).

CONCLUSION

Gastrointestinal motility is significantly impaired in patients with MDD compared to healthy control subjects. Autonomic complaints were indicated frequently in MDD patients. The duration of MDD had no influence over the time of gastric emptying. There was a significant negative correlation between the severity of MDD and T_max, indicating that the T_max was reached earlier with the progression of MDD. The slowing of gastric motility in MDD patients is likely a result of a dysfunction of the autonomic nervous system.

The effect of mirtazapine on gastric accommodation, gastric sensitivity to distention, and nutrient tolerance in healthy subjects

BACKGROUND

Disturbances of gastric motor function of functional dyspepsia (FD) have been implicated in the pathogenesis of the symptoms, and hence, motility modifying agents are considered for its treatment. Mirtazapine was recently shown to improve symptoms and increase nutrient tolerance in FD patients with weight loss. We aim to evaluate the effect of mirtazapine on gastric sensorimotor function in healthy volunteers (HV).

METHODS

Thirty-one HV underwent an intragastric pressure (IGP) and barostat measurements on separate days before and after 3 weeks of placebo or mirtazapine (15 mg). Gastric compliance, sensitivity and accommodation (GA) measured by the barostat. GA was quantitated as the difference (delta) in intra-balloon volume before and after ingestion of 200 mL of a nutrient drink (ND). GA measured by IGP was quantitated as the drop of IGP from baseline during the intragastric infusion of ND until maximal satiation.

KEY RESULTS

Mirtazapine significantly increased the bodyweight of subjects (67.8±3.7 to 69.1±3.7 kg; P=.01). Barostat results showed no effect on gastric compliance, sensitivity, and GA. Nutrient tolerance was not affected after treatment (1170±129.4 vs 1104±133.6 kcal; P=.4), and mirtazapine was associated with lower symptom ratings. The IGP drop during meal ingestion was significantly suppressed (area under the curve: -43.3±4.5 mm Hg vs -28.9±3.1 mm Hg; P=.005).

CONCLUSIONS & INFERENCES

In HVs, the occurrence of weight gain and decreased meal-induced symptoms in spite of a suppressed meal-induced IGP drop, point towards a central mode of action. Mirtazapine does not display changes in gastric sensorimotor function that could explain its beneficial effects on symptoms and nutrient tolerance in FD.

Mirtazapine for symptom control in refractory gastroparesis

Introduction

Gastroparesis symptoms can be severe and debilitating. Many patients do not respond to currently available treatments. Mirtazapine has been shown in case reports to reduce symptoms in gastroparesis.

Aim

To assess the efficacy and safety of mirtazapine in gastroparetic patients.

Methods

Adults with gastroparesis and poorly controlled symptoms were eligible. Participants were prescribed mirtazapine 15 mg PO qhs. Questionnaires containing the gastrointestinal cardinal symptom index (GCSI) and the clinical patient grading assessment scale (CPGAS) were completed by patients’ pretreatment, at 2 weeks, and at 4 weeks. Primary end point was nausea and vomiting response to mirtazapine using the GCSI. Secondary end point was nausea and vomiting severity assessment using the CPGAS. P-values were calculated using the paired two-tailed Student’s t-test. Intention to treat analysis was used.

Results

A total of 30 patients aged 19–86 years were enrolled. Of those, 24 patients (80%) completed 4 weeks of therapy. There were statistically significant improvements in nausea, vomiting, retching, and perceived loss of appetite at 2 and 4 weeks (all P-values <0.05) compared with pretreatment. There was a statistically significant improvement in the CPGAS score at week 2 (P=0.003) and week 4 (P<0.001). Of the total patients, 14 (46.7%) experienced adverse effects from mirtazapine and due to this, 6 patients stopped therapy.

Conclusion

Mirtazapine significantly improved both nausea and vomiting in gastroparetics after 2 and 4 weeks of treatment. Side effects led to treatment self-cessation in a fifth of patients. From these data, we conclude that mirtazapine improves nausea and vomiting, among other symptoms, in patients with gastroparesis and might be useful in select patients.

Investigational drug therapies for the treatment of gastroparesis

INTRODUCTION

Gastroparesis is defined by nausea, vomiting, pain, early satiety and bloating, and characterized by delayed gastric emptying without obvious structural abnormalities. Metoclopramide is widely used, increasing gastric emptying and inhibiting nausea and vomiting. Other drugs are available in certain countries and some are used 'off-label' because they increase gastric emptying or inhibit emesis. However, correlation between gastroparesis symptoms and rates of gastric emptying is poor. For anti-emetic drugs, dose-ranging and Phase III trials in gastroparesis are lacking. Areas covered: Gastric motility may still be disordered, leading to nausea, even though gastric emptying is unchanged. One hypothesis is that interstitial cells of Cajal (ICC) are damaged by diabetes leading to gastric dysrhythmia and nausea. Novel approaches to treatment of nausea also include the use of ghrelin receptor agonists, highlighting a link between appetite and nausea. Expert opinion: There is an urgent need to diversify away from historical drug targets. In particular, there is a need to control nausea by regulating ICC functions and/or by facilitating appetite via ghrelin receptor agonists. It is also important to note that different upper gastrointestinal disorders (gastroparesis, chronic unexplained nausea and vomiting, functional dyspepsia) are difficult to distinguish apart, suggesting wider therapeutic opportunity.

Centrally Targeted Pharmacotherapy for Chronic Abdominal Pain: Understanding and Management

Chronic abdominal pain has a widespread impact on the individual and the society. Identifying and explaining mechanisms of importance for the pain experience within a biopsychosocial context are central in order to select treatment that has a chance for symptom reduction. With current knowledge of brain-gut interactions, chronic abdominal pain, which mostly appears in functional gastrointestinal disorders, to a large extent involves pain mechanisms residing within the brain. As such, the use of centrally targeted pharmacotherapy as an effective treatment option is obvious in a selected number of patients. The antidepressants are most common, but also other classes of medications can be used, either alone or in combination. The latter option refers to when there is insufficient effect of one drug alone or side effects limiting dosage, and when combined in lower doses, certain drugs give rise to augmentation effects. This chapter outlines basic mechanisms of importance for the understanding of chronic abdominal pain and the pharmacologic treatment options.

Effect of Mirtazapine on Gastric Emptying in Patients with Cancer-associated Anorexia

BACKGROUND/AIMS

The tetracyclic antidepressant mirtazapine is widely used in cancer patients suffering from anorexia. Although it is known to restore appetite, the exact mechanism remains unknown. The aim of the study was to evaluate if mirtazapine has any effect on gastric emptying in patients suffering from cancer-related anorexia.

MATERIALS AND METHODS

Solid-meal gastric-emptying study using radiolabeled meal was performed in 28 patients suffering from cancer anorexia once at baseline and repeated after 15 days of mirtazapine therapy.

RESULTS

At baseline, only 7 (25%) patients had normal gastric motility (emptying >70% at 3 h postingestion) whereas after treatment, 18 (64.2%) patients achieved this limit. Mean % gastric emptying increased from 55.2% ±21.0% to 68.9% ±21.3% (P < 0.001). Mean gastric emptying time (t_1/2) before intervention was 314.7 ± 421.0 min which decreased to 116.0 ± 106.7 min after intervention. Results were further analyzed by dividing the patients into two groups based on baseline gastric-emptying study. Group A (normal gastric emptying) consisted of seven patients, mean % gastric emptying at baseline and postintervention was 75.0% ±5.25% and 87.57% ±5.94%, respectively (P < 0.018). Group B (delayed gastric emptying) consisted of 21 patients, mean % gastric emptying at baseline and postintervention was 48.71% ±18.82% and 62.76% ±16.86%, respectively (P < 0.001).

CONCLUSION

Mirtazapine significantly improves gastric emptying in patients of prostate and breast cancer suffering from cancer-associated anorexia.

Chronic Unexplained Nausea and Vomiting or Gastric Neuromuscular Dysfunction (GND)? An Update on Nomenclature, Pathophysiology and Treatment, and Relationship to Gastroparesis

OPINION STATEMENT

Chronic unexplained nausea and vomiting is a debilitating condition that dramatically decreases patient quality of life and creates diagnostic and treatment challenges for healthcare providers. Additionally, the significant overlap in symptoms between disorders such as chronic unexplained nausea and vomiting, gastroparesis, and functional dyspepsia has resulted in a blurring of diagnostic lines and added confusion to the therapeutic approach. The identified overlap in clinical symptoms also suggests a common underlying pathophysiological mechanism may drive these conditions, indicating they could possibly be part of a spectrum of gastric neuromuscular disorders instead of discrete processes. This article will discuss the classification, updates in pathophysiology and therapeutic research, and future directions of research in the treatment of chronic unexplained nausea and vomiting.

Newest Drugs for Chronic Unexplained Nausea and Vomiting

OPINION STATEMENT

Chronic unexplained nausea and vomiting (CUNV) refers to a symptom complex defined by nausea and/or vomiting with normal diagnostic testing, including anatomic assessments (including upper endoscopy) and measures of upper gut function (e.g., gastric emptying testing). Nausea and vomiting in this condition are postulated to result from aberrant peripheral or central neurohumoral activity. A substantial subset of patients satisfies this diagnosis as more than half of individuals referred for scintigraphic testing exhibit normal gastric emptying rates. No randomized, placebo-controlled trials of any medication treatment have been performed in CUNV. However, agents with potential therapeutic benefits in CUNV include antiemetic drugs, neuromodulatory treatments which are proposed to act by reducing gastric sensitivity, and medications with prokinetic action to stimulate upper gut propulsion. Recently approved drugs with antiemetic capability include serotonin antagonists with novel modes of delivery and neurokinin antagonists with or without additional serotonergic blocking capabilities. Existing neuroleptics and pain-modifying neuromodulatory therapies with fortuitous antiemetic benefits are being considered for their benefits in this disorder. Furthermore, current investigations will define potential therapeutic actions of agents that stimulate gastric emptying via action on gastroduodenal serotonin, motilin, and ghrelin receptors. This current research may broaden the treatment options for refractory cases of unexplained nausea and vomiting.

Emerging strategies for the treatment of gastroparesis

Gastroparesis is a syndrome of delayed gastric emptying in the absence of mechanical obstruction. Symptoms can be debilitating, affect nutritional states, and significantly impact patients' quality of life. The management of these patients can prove quite difficult to many providers. This article will review the current management recommendations of gastroparesis, discuss investigational medications and interventions, and summarize future directions of therapies targeting the underlying disease process. Current therapies are subdivided into those improving gastric motility and those directly targeting symptoms. Non-pharmacologic interventions, including gastric stimulator implantation and intra-pyloric botulinum toxic injection are reviewed. A discussion of expert opinion in the field, a look into the future of gastroparesis management, and a key point summary conclude the article.

Functional Dyspepsia and Gastroparesis

BACKGROUND

Upper gastrointestinal disorders typically present with common symptoms. The most relevant non-mucosal diseases are gastroparesis, functional dyspepsia and rumination syndrome. The literature pertaining to these 3 conditions was reviewed.

KEY MESSAGES

Gastroparesis is characterized by delayed gastric emptying in the absence of mechanical obstruction of the stomach. The cardinal symptoms include postprandial fullness (early satiety), nausea, vomiting and bloating. The most frequently encountered causes of these symptoms are mechanical obstruction (pyloric stenosis), iatrogenic disease, gastroparesis, functional dyspepsia, cyclical vomiting and rumination syndrome. The most common causes of gastroparesis are neuropathic disorders such as diabetes, idiopathic, post-vagotomy and scleroderma among myopathic disorders. Principles of management of gastroparesis include exclusion of mechanical obstruction with imaging and iatrogenic causes with careful medication and past surgical history. Prokinetics and anti-emetics are the mainstays of treatment. Functional dyspepsia is characterized by the same symptoms as gastroparesis; in addition to delayed gastric emptying, pathophysiological abnormalities include accelerated gastric emptying, impaired gastric accommodation and gastric or duodenal hypersensitivity to distension and nutrients. Novel treatments include tricyclic antidepressants in patients with normal gastric emptying, acotiamide (acetyl cholinesterase inhibitor) and 5-HT1A receptor agonists such as buspirone. Rumination syndrome is characterized by repetitive regurgitation of gastric contents occurring within minutes after a meal. Episodes often persist for 1-2 h after the meal, and the regurgitant consists of partially digested food that is recognizable in its taste. Regurgitation is typically effortless or preceded by a sensation of belching. This has been summarized as a 'meal in, meal out, day in, day out' behavior for weeks or months, differentiating rumination from gastroparesis. Patients often have a background of psychological disorder or a prior eating disorder. Treatment is based on behavioral modification.

CONCLUSION

Precise identification of the cause and pathophysiology of upper gastrointestinal symptoms is essential for optimal management.

Early investigational therapeutics for gastrointestinal motility disorders: from animal studies to Phase II trials

INTRODUCTION

The most common gastrointestinal disorders that include evidence of dysmotility include: gastroparesis, the lower functional gastrointestinal disorders associated with altered bowel function (such as chronic [functional] diarrhea, chronic idiopathic constipation) and opioid-induced constipation. These conditions, which are grouped as gastrointestinal motility and functional disorders, are characterized by abnormal motor, sensory or secretory functions that alter bowel function and result in a significant disease burden, since currently available treatments do not completely alleviate symptoms. New drugs are being developed for these disorders, targeting mechanisms involved in the pathophysiology of these diseases, specifically, motor function, intestinal secretion and bile acid modulation.

AREAS COVERED

The article provides a brief overview of motility disorders and the drugs approved and currently available for these indications. It also provides an evaluation of the efficacy, safety and possible mechanisms of the drugs currently under investigation for the treatment of gastroparesis, chronic diarrhea, chronic idiopathic constipation and opioid-induced constipation, based on animal to Phase II studies. Medications with complete Phase III trials are excluded from this discussion.

EXPERT OPINION

Treatment of gastrointestinal motility disorders requires the understanding of the pathophysiological mechanisms, biomarkers to identify subgroups of these disorders and robust pharmacological studies from animal to Phase II studies. These are prerequisites for the development of efficacious medications and individualizing therapy in order to enhance the treatment of these patients.

The clinical-psychological features of functional dyspepsia patients with weight loss: a multi-center study from China

AIMS

To investigate the clinical features, appetite, quality of life (QOL), and their associated psychological factors of functional dyspepsia (FD) patients with weight loss.

METHODS

For a multicenter study, FD patients were recruited and divided into two groups according to the degree of weight changes during the previous 12 months or less with the onset of dyspepsia symptoms: Group A (≥5%) and Group B (<5%). Patients were evaluated based on the Nepean dyspepsia index (NDI), appetite questionnaire, Hamilton Rating Scale of Anxiety/Depression (HAMA/HAMD).

RESULTS

The body mass index in Group A was lower than in Group B, while, the frequency of physician visits in Group A was higher than in Group B. There were no differences in the total scores of NDI-symptom checklist or the items of intensity and bothersomeness between them (p > 0.05), but the frequency item for Group A was significantly higher than Group B (p = 0.035). The incidence of anxiety or depression, the proportion of poor or very poor appetite for Group A was higher than those for Group B (p < 0.05). Subscale scores of the NDI-QOL for Group A were significantly lower than those for Group B (p < 0.05).

CONCLUSIONS

FD patients with weight loss have lower BMI, more frequent physician visits, higher psychological disorders, poorer appetite and QoL.

Electrical neuromodulation at acupoint ST36 normalizes impaired colonic motility induced by rectal distension in dogs

Electroacupuncture (EA) has been shown to improve impaired gastric motility and slow waves in both humans and animals. However, its effects on colonic motility have rarely been investigated. The aim of this study was to investigate the effects and underlying mechanisms of EA on impaired colonic motility induced by rectal distension (RD)in dogs. Colon contractions and transit were measured in various sessions with and without EA in hound dogs chronically placed with a colonic cannula. Colonic contractile activity was assessed by motility index (MI). Autonomic functions were determined by the spectral analysis of the heart rate variability derived from the electrocardiogram. It was found 1) RD suppressed colonic motility by 40.5% (10.8 ± 0.9 with RD vs. 6.4 ± 0.8 at baseline, P < 0.002). EA at ST36 normalized colonic contractions suppressed by RD (12.9 ± 2.8, P < 0.002 vs. RD and P = 0.1 vs. control). 2) Administration of atropine blocked the ameliorating effect of EA on colon motility. 3) RD also delayed colonic transit (65.0 ± 2.0% with RD vs. 86.0 ± 1.9% without RD, P < 0.001) that was restored with EA (84.0 ± 1.9%, P = 0.178 vs. control). 4) EA increased vagal activity suppressed by RD (0.37 ± 0.07 with RD + EA vs. 0.09 ± 0.03 with RD without EA, P < 0.001). In conclusion, RD inhibits colonic contractions and delays colonic transit in dogs; EA at ST36 restores the RD-induced impairment in both colonic contraction and transit by enhancing vagal activity and mediated via the cholinergic pathway.

Current advances in treatment of gastroparesis

INTRODUCTION

Gastroparesis is a syndrome defined by delayed gastric emptying in the absence of mechanical obstruction. Gastroparesis has significant symptomatology and negative impacts on the patient's quality of life.

AREAS COVERED

This article reviews current treatment options for gastroparesis, recent advances in treatment and future directions that treatment may head. Current options are broadly divided into prokinetics and symptom modulators. Within each group, current modalities as well as recent advances are discussed according to agent mechanism of action. Lastly, findings regarding the cellular pathophysiology involved in gastroparesis will be briefly reviewed along with their implications for future treatments.

EXPERT OPINION

The numerous motor functions and neural inputs that control gastric motility are complex and not fully understood. Our lack of understanding of its pathophysiology has led to treatment options which are empirical, palliative and often ineffective. Newly intensified interest in the cellular pathophysiology behind gastroparesis provides promise for a new era of treatments. Identification of common cellular changes in gastroparesis has provided targets for treatment that may allow us to one day better treat the symptoms of gastroparesis related to its underlying pathophysiology. This is the future of gastroparesis therapy.

Symptomatic management for gastroparesis: antiemetics, analgesics, and symptom modulators

Although prokinetic agents typically are used for gastroparesis, antiemetic, analgesic, and neuromodulatory medications may help manage nausea, vomiting, pain, or discomfort. Antiemetic benefits are supported by few case reports. An open series reported symptom reductions with transdermal granisetron in gastroparesis. Opiates are not advocated in gastroparesis because they worsen nausea and delay emptying. Neuromodulators have theoretical utility, but the tricyclic agent nortriptyline showed no benefits over placebo in an idiopathic gastroparesis study raising doubts about this strategy. Neurologic and cardiac toxicities of these medications are recognized. Additional controlled study is warranted to define antiemetic, analgesic, and neuromodulator usefulness in gastroparesis.

Future directions in the treatment of gastroparesis

Understanding of gastroparesis is evolving, in part because of systematic studies on the pathology, pathophysiology, and outcomes. It is clear that simply accelerating gastric emptying may not effectively control symptoms in this syndrome and more creative approaches are required that address aberrant sensation (vagal and spinal) as well as regional disturbances in motility. Further, with the growing recognition of a possible inflammatory basis, the prospects of disease modifying now seem realistic.