Influence of gastric acid on gastric emptying and gastric distension-induced pain response in rats--effects of famotidine and mosapride

Treatment of Gastrointestinal Disorders-Plants and Potential Mechanisms of Action of Their Constituents

The worldwide prevalence of gastrointestinal diseases is about 40%, with standard pharmacotherapy being long-lasting and economically challenging. Of the dozens of diseases listed by the Rome IV Foundation criteria, for five of them (heartburn, dyspepsia, nausea and vomiting disorder, constipation, and diarrhoea), treatment with herbals is an official alternative, legislatively supported by the European Medicines Agency (EMA). However, for most plants, the Directive does not require a description of the mechanisms of action, which should be related to the therapeutic effect of the European plant in question. This review article, therefore, summarizes the basic pharmacological knowledge of synthetic drugs used in selected functional gastrointestinal disorders (FGIDs) and correlates them with the constituents of medicinal plants. Therefore, the information presented here is intended as a starting point to support the claim that both empirical folk medicine and current and decades-old treatments with official herbal remedies have a rational basis in modern pharmacology.

Effect of Combination Therapy of Oral Famotidine with Mosapride on Intragastric pH and Gastric Emptying in Rats

Background/Aims: Studies in healthy humans have reported that the addition of mosapride to acid suppressants resulted in higher intragastric pH than acid suppressant administration alone. We investigated the effect of the addition of mosapride to famotidine on the intragastric pH and gastric emptying rate (GER) in rats.Materials and Methods: Sixty male Wistar rats were used in this study. Experimental groups were divided into control, famotidine-only, mosapride-only, and famotidine with mosapride (combination). The first experiment was performed in non-stressed rats. Mosapride was administered by oral gavage 1 hour before the meal, and famotidine was administered just before the meal. The rats were provided with food for 30 minutes. The intragastric pH was measured under isoflurane anesthesia, and the GER was measured after harvesting the stomach. In the stress experiment, rats were exposed to 1-hour restraint stress immediately after mosapride administration and subjected to the same process as in the experiment with the non-stressed rats.Results: The famotidine-only and combination groups showed significantly higher gastric pH levels than the control group in non-stressed (P<0.01 and P<0.001, respectively) and stressed (P<0.001 and P<0.001, respectively) rats. The combination group also showed significantly higher intragastric pH levels than the famotidine-only group in non-stressed (P<0.01) and stressed (P<0.05) rats. Additionally, combination groups showed a significantly higher GER than the famotidine-only group in non-stressed (P<0.001) and stressed (P<0.01) rats.Conclusions: The combination of mosapride with famotidine significantly increased intragastric pH compared to famotidine alone in the non-stressed and stressed rats.

Efficacy of acotiamide on postprandial distress syndrome and epigastric pain syndrome depending on the estimated gastric acid secretion level

Background/Aims

Gastric acid secretion is suspected to be a pivotal contributor to the pathogenesis of functional dyspepsia. The present study investigates the potential association of the gastric acid secretion estimated by measuring serum pepsinogen with therapeutic responsiveness to the prokinetic drug acotiamide.

Methods

Dyspeptic patients consulting participating clinics from October 2017 to March 2019 were prospectively enrolled in the study. The dyspeptic symptoms were classified into postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS). Gastric acid secretion levels were estimated by the Helicobacter pylori infection status and serum pepsinogen using established criteria and classified into hypo-, normo-, and hyper-secretion. Each patient was then administered 100 mg acotiamide thrice daily for 4 weeks, and the response rate to the treatment was evaluated using the overall treatment efficacy scale.

Results

Of the 86 enrolled patients, 56 (65.1%) and 26 (30.2%) were classified into PDS and EPS, respectively. The estimated gastric acid secretion was not significantly different between PDS and EPS. The response rates were 66.0% for PDS and 73.1% for EPS, showing no significant difference. While the response rates were stable, ranging from 61.0% to 75.0% regardless of the estimated gastric acid secretion level among subjects with PDF, the rates were significantly lower in hyper-secretors than in non-hyper-secretors among subjects with EPS (42.0% vs 83.0%, P = 0.046).

Conclusion

Although acotiamide is effective for treating EPS as well as PDS overall, the efficacy is somewhat limited in EPS with gastric acid hyper-secretion, with gastric acid suppressants, such as proton pump inhibitors, being more suitable.

Assessment of gastric acidity by short-duration intragastric pH-monitoring with standardised breakfast in functional and some other dyspepsias

Introduction

Preliminary assessment of gastric secretion in the treatment of organic and functional dyspepsia may offer advantages over the empirical administration of proton pump inhibitors suggested by most clinical guidelines.

Aim

To develop a simplified pH-metric test with standardised meal, and on its basis to perform an assessment of the functional state of gastric secretion in the most common dyspepsias.

Material and methods

Serum pepsinogen 1 and 2 were used for reference. Intragastric pH-monitoring was performed during 45 min in basal phase and 135 min after provocative breakfast (507 kcal, 100 mg caffeine). Consecutive adults enrolled in the study were divided into groups: 1 – “Non-dyspeptic” – 30 persons; 2 – “Duodenal peptic ulcer” – 13; 3 – “GERD” – 82; and 4 – “Functional dyspepsia” – 125 patients.

Results

There was a moderate association between concentration of pepsinogen-1 and parameters of pH-monitoring. The best correlation coefficients were for the nadir pH in basal conditions and the time of acid neutralisation > 3.5 after the meal – r = –0.534 and r = –0.541, respectively (p < 0.0001). Using these two parameters we considered discriminants for four patterns of acidity. Proposed criteria of Hipo-anacidity included an absence of active secretion of hydrochloric acid in basal (pHmin > 5) and postprandial phases, with the achievement of stable pH < 3.5 after 80 min from meal time. They showed sensitivity 88.9% and specificity 100%. In cases of a detected pattern of hyperacidity, these parameters were 80% and 66.67%, respectively. According to the prevalence of hyperacidic cases, the groups were ranked in the following order: duodenal ulcer (76.9%) – GERD (51.1%) – functional dyspepsia (40.8%) – non-dyspeptic (19.0%).

Conclusions

Acid production is increased among patients with functional dyspepsia. There is a small number of patients with functional dyspepsia (12.1%) with hypochlorhydria due to atrophic gastritis. The latter was independently associated with age > 50 years (OR = 20.139), symptoms of postprandial distress-syndrome (OR = 9.821), and signs of atrophy (OR = 5.914) after conventional endoscopy.

Review article: treatment options for functional dyspepsia

BACKGROUND

Functional dyspepsia, consisting of epigastric pain syndrome and postprandial distress syndrome, is a prevalent functional gastrointestinal disorder. To date, only limited treatment options are available and conflicting results in terms of efficacy have been reported. Consequently, nonpharmacological treatment options are increasingly being explored for functional dyspepsia.

AIM

To provide an overview of current pharmacological and nonpharmacological treatment options for functional dyspepsia.

METHODS

A literature search was conducted on Pubmed and other sources to identify relevant studies.

RESULTS

Acid suppressive therapy reduced symptoms in 30%-70% of the patients, with higher benefit in epigastric pain syndrome and superior effectiveness for proton pump inhibitors compared to H₂ -antagonists. Prokinetic agents, primarily used to treat postprandial distress syndrome, showed variable efficiency: 59%-81% responder rate for dopamine receptor antagonists, 32%-91% for serotonin-4-receptor agonists and 31%-80% for muscarinic receptor antagonists. H Pylori eradication, recommended in infected patients, was effective in 24%-82%. Refractory symptoms are addressed with neuromodulators. However, their efficacy in functional dyspepsia remains incompletely elucidated, available data showing symptom reduction in 27%-71% of the patients. Regarding herbal agents, peppermint oil reduced symptoms in 66%-91%, rikkunshito in 29%-34% and iberogast in 20%-95%. Lastly, acupuncture, cognitive behavioural therapy and hypnotherapy may help to provide symptom control, but research on their efficacy remains sparse.

CONCLUSIONS

None of the available therapies is effective in the majority of patients without being associated with major side effects. Developing new treatment options is challenging due to the heterogeneity of functional dyspepsia, the lack of readily identified target mechanisms and the poor association between pathophysiological disturbances and symptoms.

Protein Kinase C Mediates the Corticosterone-induced Sensitization of Dorsal Root Ganglion Neurons Innervating the Rat Stomach

BACKGROUND/AIMS

Gastric hypersensitivity contributes to abdominal pain in patients with functional dyspepsia. Recent studies showed that hormones induced by stress are correlated with visceral hypersensitivity. However, the precise mechanisms underlying gastric hypersensitivity remain largely unknown. The aim of the present study was designed to investigate the roles of corticosterone (CORT) on excitability of dorsal root ganglion (DRG) neurons innervating the stomach.

METHODS

DRG neurons innervating the stomach were labeled by DiI injection into the stomach wall. Patch clamp recordings were employed to examine neural excitability and voltage-gated sodium channel currents. Electromyograph technique was used to determine the responses of neck muscles to gastric distension.

RESULTS

Incubation of acutely isolated DRG neurons with CORT significantly depolarized action potential threshold and enhanced the number of action potentials induced by current stimulation of the neuron. Under voltage-clamp mode, incubation of CORT enhanced voltage-gated sodium current density of the recorded neurons. Pre-incubation of GF109203X, an inhibitor of protein kinase C, blocked the CORT-induced hyperexcitability and potentiation of sodium currents. However, pre-incubation of H-89, an inhibitor of protein kinase A, did not alter the sodium current density. More importantly, intraperitoneal injection of CORT produced gastric hypersensitivity of healthy rats, which was blocked by pre-administration of GF109203X but not H-89.

CONCLUSIONS

Our data strongly suggest that CORT rapidly enhanced neuronal excitability and sodium channel functions, which is most likely mediated by protein kinase C but not protein kinase A signaling pathway in DRG neurons innervating the stomach, thus underlying the gastric hypersensitivity induced by CORT injection.

Efficacy of mosapride and pantoprazole in treatment of children with functional dyspepsia

AIM: To compare the efficacy and safety of mosapride and pantoprazole in the treatment of children with functional dyspepsia.

METHODS: Sixty children with functional dyspepsia were selected and randomly divided into either an observation group or a control group, with 30 cases in each group. Subjects in the observation group were treated with mosapride (5 mg, po, tid). Subjects in the control group were treated with pantoprazole (40 mg, po, qd). After 2 wk of treatment, the symptom score and clinical efficacy of the two groups were observed and compared.

RESULTS: After treatment, the scores of total symptoms, abdominal fullness after meals, early satiety, epigastric pain, and epigastric burning sensation in the two groups were significantly lower than those before the treatment (observation group: 14.39 ± 7.13 vs 20.79 ± 11.36, 4.39 ± 1.37 vs 4.84 ± 5.16, 3.89 ± 1.19 vs 4.17 ± 4.43, 3.74 ± 1.05 vs 6.37 ± 5.36, 3.95 ± 1.98 vs 6.73 ± 6.21; control group: 13.57 ± 6.42 vs 20.68 ± 11.41, 3.27 ± 1.16 vs 4.91 ± 5.21, 3.16 ± 1.08 vs 4.20 ± 4.52, 4.29 ± 1.23 vs 6.29 ± 5.83, 4.17 ± 1.54 vs 6.82 ± 6.08; P < 0.05 for all). The scores of total symptoms, abdominal fullness after meals, early satiety, epigastric pain, and epigastric burning sensation after treatment showed no significant differences between the two groups (P > 0.05 for all). The difference in the total response rate between the two groups was not statistically significant (70.00% vs 66.67%, P > 0.05). There were no significant differences in the response rates for postprandial distress syndrome and epigastric pain syndrome between the two groups (70.59% vs 64.71%, 69.23% vs 69.23%, P > 0.05 for both).

CONCLUSION: Both mosapride and pantoprazole have good efficacy in the treatment of children with functional dyspepsia.

Evaluation of Acid Tolerance of Drugs Using Rats and Dogs Controlled for Gastric Acid Secretion

We attempted to establish animal models to evaluate the effects of drug degradation in the stomach on oral bioavailability. In addition, we assessed the utilization of animal studies in determining the need for enteric-coated formulations. In order to control the gastric pH in rats and dogs, appropriate dosing conditions were investigated using pentagastrin and rabeprazole, which stimulate and inhibit gastric acid secretion. Using animals controlled for gastric acid secretion, the area under curve (AUC) ratios (AUC with rabeprazole/AUC with pentagastrin) of all compounds unstable under acidic conditions were evaluated. The AUC ratios of omeprazole and erythromycin, which are administered orally to humans, as enteric-coated tablets, were greater than 1.9 in the rats and dogs controlled for gastric acid secretion. On the contrary, the AUC ratios of clarithromycin, azithromycin, and etoposide (commercially available as a standard immediate-release form) were less than 1.3 each. In conclusion, in vivo models using rats and dogs were optimized to evaluate the effects of gastric acid on the oral bioavailability of drugs, and demonstrated that in vivo models can lead to a better understanding of the oral bioavailability, with respect to the formulation development.

Functional dyspepsia and brain-gut peptides

Functional dyspepsia (FD) is a frequently occurring gastrointestinal disorder, but its etiology and pathogenesis are still unclear because it is associated with multiple factors. As a typically physical and psychological disease, the role of psychological factors in the pathogenesis of FD involves the brain-gut axis, mainly abnormal stimulation processing by the central nervous system and abnormal levels of brain-gut peptides. Brain-gut peptides are the molecular basis of the action of the brain-gut axis, and the brain-gut axis affects the occurrence of FD by regulating the levels of brain-gut peptides. So far, 15 brain-gut peptides associated with FD have been found, which are predominantly expressed in the hypothalamus, medulla oblongata, spinal cord and gastrointestinal mucosa. The aim of this study is to clarify the relationship between brain-gut peptide levels and the occurrence of FD based on brain-gut peptide in terms of their secretion and mechanisms of action.