Recent advances in pharmacological treatment of irritable bowel syndrome

The Effect of Phloroglucinol in Patients With Diarrhea-predominant Irritable Bowel Syndrome: A Randomized, Double-blind, Placebo-controlled Trial

Background/Aims

We aim to evaluate the efficacy and safety of phloroglucinol in patients with diarrhea-predominant irritable bowel syndrome (IBS-D).

Methods

Seventy-two patients with IBS-D who met Rome III criteria were 1:1 randomized in a parallel, double-blind design to receive phloroglucinol or placebo for 2 weeks. Patients were followed for 1 week after the end of treatment. The primary outcome was the proportion of responders, defined as those who answered “moderate or more of improvement” to the subject global assessment for at least 1 week of the 2-week treatment period. Secondary outcomes included the proportion of these patients during the 3-week period including 1 week of follow-up, IBS symptoms (abdominal pain/discomfort, diarrhea, urgency, mucus in stool, bloating, and passage of gas), stool frequency and consistency, and IBS quality of life (IBS-QOL).

Results

The proportion of responders during 2-week treatment period tended to be higher in the phloroglucinol group than in the placebo group, although the difference did not reach statistical significance (55.6% vs 30.6%, P = 0.056). The proportion of responders during the 3-week period was significantly higher in the phloroglucinol group than in the placebo group (61.6% vs 30.6%, P = 0.013). Individual symptom scores, IBS-QOL, stool frequency and consistency tended to improve in the phloroglucinol group, but there were no statistical significances compared to those of the placebo group. No serious adverse events were reported in both groups.

Conclusions

Phloroglucinol could be a safe and beneficial option for the management of overall IBS symptoms in patients with IBS-D. Further large scaled studies are warranted.

Gastroprokinetic agent, mosapride inhibits 5-HT3 receptor currents in NCB-20 cells

Mosapride accelerates gastric emptying by acting on 5-hydroxytryptamine type 4 (5-HT₄) receptor and is frequently used in the treatment of gastrointestinal (GI) disorders requiring gastroprokinetic efficacy. We tested the effect of mosapride on 5-hydroxytryptamine type 3 (5-HT₃) receptor currents because the 5-HT₃ receptors are also known to be expressed in the GI system and have an important role in the regulation of GI functions. Using the whole-cell voltage clamp method, we compared the currents of the 5-HT₃ receptors when 5-HT was applied alone or was co-applied with mosapride in cultured NCB-20 cells known to express 5-HT₃ receptors. The 5-HT₃ receptor current amplitudes were inhibited by mosapride in a concentration-dependent manner. Mosapride blocked the peak currents evoked by the application of 5-HT in a competitive manner because the EC₅₀ shifted to the right without changing the maximal effect. The rise slopes of 5-HT₃ receptor currents were decreased by mosapride. Pre-application of mosapride before co-application, augmented the inhibitory effect of mosapride, which suggests a closed channel blocking mechanism. Mosapride also blocked the opened 5-HT₃ receptor because it inhibited the 5-HT₃ receptor current in the middle of the application of 5-HT. It accelerated desensitization of the 5-HT₃ receptor but did not change the recovery process from the receptor desensitization. There were no voltage-, or use-dependency in its blocking effects. These results suggest that mosapride inhibited the 5-HT₃ receptor through a competitive blocking mechanism probably by binding to the receptor in closed state, which could be involved in the pharmacological effects of mosapride to treat GI disorders.

Antioxidant Supplements and Gastrointestinal Diseases: A Critical Appraisal

The gastrointestinal tract digests and absorbs dietary nutrients, protects the body against physical and chemical damage from contents in its lumen, provides immunity against external antigens, and keeps an optimum environment for the gut microbiota. These functions cannot be performed normally in several diseases of which the following are discussed here: irritable bowel syndrome and inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis. Because these diseases are associated with oxidative stress, a host of antioxidant supplements are used for maintenance and recovery of the gut functions. However, the benefits of these supplements have not been established. The available 80 human trials were rated for levels of confidence and for benefits of the antioxidant supplements. For Crohn's disease, the supplements for which clear benefits occurred in at least 2 studies were allopurinol, Boswellia serrata (frankincense or shallaki), Artemesia species (wormwood), Tripterygium wilfordii (léi gōng téng), and omega-3 fatty acids. Similar beneficial supplements for ulcerative colitis were allopurinol, Matricaria chamomilla (chamomile), Curcuma longa (curcumin in turmeric), and omega-3 fatty acids. There was also a clear benefit for ulcerative colitis in 2 studies where a multiherbal Chinese medicine preparation and an Ayurvedic medicine preparation were used. For irritable bowel syndrome, there was only a marginal benefit of some of the antioxidant supplements. Thus, some antioxidant supplements may be beneficial at certain stages of specific diseases. This is consistent with the current concept that antioxidants act by inhibiting oxidative stress pathways in a tissue- and environment-specific manner and not by simply acting as scavengers.

Progress in treatment of irritable bowel syndrome

Irritable bowel syndrome is a common functional bowel disorder whose incidence has a tendency to increase year by year. At present, the pathogenesis of irritable bowel syndrome is not completely clear, and treatments are mainly symptomatic. In recent years, with the better understanding of its pathogenesis, some new drugs and treatments have been developed, such as methods of improving intestinal micro-ecology (antibiotics, fecal transplantation), mesalazine, and new drugs of improving intestinal secretion, motiligy and sensitivity, plant drugs, some of which have been applied clinically. This article will make a review of the current progress in treatment of irritable bowel syndrome.

Probiotic for irritable bowel syndrome in pediatric patients: a randomized controlled clinical trial

Background:

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder in children. Recently, probiotics have been suggested as a treatment option for gastrointestinal disorders. The most effective species and the most appropriate doses are still unknown.

Objective:

The aim of this study was to assess the effects of Lactobacillus GG (LGG) for treating IBS in pediatric patients.

Methods:

In a controlled, double blind, randomized trial, patients with IBS diagnosed by Rome III criteria from August 2012 to September 2012 at Dr. Sheikh Hospital, Mashhad University of Medical Sciences, Iran, were assigned to one of two groups, i.e., intervention and control groups. For four weeks, the intervention group received a probiotic in capsule form that contained LGG at a concentration of 1×10¹⁰ cfu/ml bacteria. For the same period, the control group received a placebo capsule that had the same shape and color but only contained inulin, which also was present in the LGG capsules. The primary outcome was any change in the severity of the patients’ pain, and we used a five-point Likert scale to evaluate the severity of their pain. Secondary outcomes were ghanges of the functional scale, stool patterns, and associated problems.

Results:

Fifty-two patients participated in the study, and 26 patients were assigned randomly to each of the two groups. The severity of the patients’ pain decreased significantly in the intervention group after one, two, three, and four weeks of treatment, as indicated by P-values of 0.01, 0.00, 0.00, and 0.00, respectively. Also, there was significant improvement in the functional scale after two weeks of treatment (P-value ≤ 0.00).

Conclusion:

Lactobacillus GG at a concentration of 1×10¹⁰ cfu/ml for a period of four weeks can lessen the severity of the patients’ pain and improve the functional scale in patients with irritable bowel syndrome. Probiotics can have therapeutic effects for IBS patients.

Stress-induced visceral pain: toward animal models of irritable-bowel syndrome and associated comorbidities

Visceral pain is a global term used to describe pain originating from the internal organs, which is distinct from somatic pain. It is a hallmark of functional gastrointestinal disorders such as irritable-bowel syndrome (IBS). Currently, the treatment strategies targeting visceral pain are unsatisfactory, with development of novel therapeutics hindered by a lack of detailed knowledge of the underlying mechanisms. Stress has long been implicated in the pathophysiology of visceral pain in both preclinical and clinical studies. Here, we discuss the complex etiology of visceral pain reviewing our current understanding in the context of the role of stress, gender, gut microbiota alterations, and immune functioning. Furthermore, we review the role of glutamate, GABA, and epigenetic mechanisms as possible therapeutic strategies for the treatment of visceral pain for which there is an unmet medical need. Moreover, we discuss the most widely described rodent models used to model visceral pain in the preclinical setting. The theory behind, and application of, animal models is key for both the understanding of underlying mechanisms and design of future therapeutic interventions. Taken together, it is apparent that stress-induced visceral pain and its psychiatric comorbidities, as typified by IBS, has a multifaceted etiology. Moreover, treatment strategies still lag far behind when compared to other pain modalities. The development of novel, effective, and specific therapeutics for the treatment of visceral pain has never been more pertinent.